draft-ietf-mboned-mtrace-v2-09.txt   draft-ietf-mboned-mtrace-v2-10.txt 
MBONED Working Group H. Asaeda MBONED Working Group H. Asaeda
Internet-Draft NICT Internet-Draft NICT
Intended status: Standards Track W. Lee, Ed. Intended status: Standards Track W. Lee, Ed.
Expires: April 25, 2013 Juniper Networks, Inc. Expires: January 10, 2014 Juniper Networks, Inc.
October 22, 2012 July 09, 2013
Mtrace Version 2: Traceroute Facility for IP Multicast Mtrace Version 2: Traceroute Facility for IP Multicast
draft-ietf-mboned-mtrace-v2-09 draft-ietf-mboned-mtrace-v2-10
Abstract Abstract
This document describes the IP multicast traceroute facility, named This document describes the IP multicast traceroute facility, named
Mtrace version 2 (Mtrace2). Unlike unicast traceroute, Mtrace2 Mtrace version 2 (Mtrace2). Unlike unicast traceroute, Mtrace2
requires special implementations on the part of routers. This requires special implementations on the part of routers. This
specification describes the required functionality in multicast specification describes the required functionality in multicast
routers, as well as how an Mtrace2 client invokes a query and routers, as well as how an Mtrace2 client invokes a query and
receives a reply. receives a reply.
Status of this Memo Status of This Memo
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provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on April 25, 2013. This Internet-Draft will expire on January 10, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . 6 2.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . 5
3. Packet Formats . . . . . . . . . . . . . . . . . . . . . . . . 7 3. Packet Formats . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Mtrace2 TLV format . . . . . . . . . . . . . . . . . . . . 8 3.1. Mtrace2 TLV format . . . . . . . . . . . . . . . . . . . 7
3.2. Defined TLVs . . . . . . . . . . . . . . . . . . . . . . . 8 3.2. Defined TLVs . . . . . . . . . . . . . . . . . . . . . . 7
3.2.1. Mtrace2 Query . . . . . . . . . . . . . . . . . . . . 9 3.2.1. Mtrace2 Query . . . . . . . . . . . . . . . . . . . . 8
3.2.2. Mtrace2 Extended Query Block . . . . . . . . . . . . . 10 3.2.2. Mtrace2 Request . . . . . . . . . . . . . . . . . . . 10
3.2.3. Mtrace2 Request . . . . . . . . . . . . . . . . . . . 11 3.2.3. Mtrace2 Reply . . . . . . . . . . . . . . . . . . . . 10
3.2.4. Mtrace2 Reply . . . . . . . . . . . . . . . . . . . . 11 3.2.4. IPv4 Mtrace2 Standard Response Block . . . . . . . . 10
3.2.5. IPv4 Mtrace2 Standard Response Block . . . . . . . . . 12 3.2.5. IPv6 Mtrace2 Standard Response Block . . . . . . . . 14
3.2.6. IPv6 Mtrace2 Standard Response Block . . . . . . . . . 16 3.2.6. Mtrace2 Augmented Response Block . . . . . . . . . . 17
3.2.7. Mtrace2 Augmented Response Block . . . . . . . . . . . 19 3.2.7. Mtrace2 Extended Query Block . . . . . . . . . . . . 18
4. Router Behavior . . . . . . . . . . . . . . . . . . . . . . . 20 4. Router Behavior . . . . . . . . . . . . . . . . . . . . . . . 19
4.1. Receiving Mtrace2 Query . . . . . . . . . . . . . . . . . 20 4.1. Receiving Mtrace2 Query . . . . . . . . . . . . . . . . . 19
4.1.1. Query Packet Verification . . . . . . . . . . . . . . 20 4.1.1. Query Packet Verification . . . . . . . . . . . . . . 19
4.1.2. Query Normal Processing . . . . . . . . . . . . . . . 21 4.1.2. Query Normal Processing . . . . . . . . . . . . . . . 20
4.2. Receiving Mtrace2 Request . . . . . . . . . . . . . . . . 21 4.2. Receiving Mtrace2 Request . . . . . . . . . . . . . . . . 20
4.2.1. Request Packet Verification . . . . . . . . . . . . . 21 4.2.1. Request Packet Verification . . . . . . . . . . . . . 20
4.2.2. Request Normal Processing . . . . . . . . . . . . . . 22 4.2.2. Request Normal Processing . . . . . . . . . . . . . . 20
4.3. Forwarding Mtrace2 Request . . . . . . . . . . . . . . . . 23 4.3. Forwarding Mtrace2 Request . . . . . . . . . . . . . . . 22
4.3.1. Destination Address . . . . . . . . . . . . . . . . . 24 4.3.1. Destination Address . . . . . . . . . . . . . . . . . 22
4.3.2. Source Address . . . . . . . . . . . . . . . . . . . . 24 4.3.2. Source Address . . . . . . . . . . . . . . . . . . . 22
4.3.3. Appending Standard Response Block . . . . . . . . . . 24 4.3.3. Appending Standard Response Block . . . . . . . . . . 23
4.4. Sending Mtrace2 Reply . . . . . . . . . . . . . . . . . . 24 4.4. Sending Mtrace2 Reply . . . . . . . . . . . . . . . . . . 23
4.4.1. Destination Address . . . . . . . . . . . . . . . . . 25 4.4.1. Destination Address . . . . . . . . . . . . . . . . . 23
4.4.2. Source Address . . . . . . . . . . . . . . . . . . . . 25 4.4.2. Source Address . . . . . . . . . . . . . . . . . . . 23
4.4.3. Appending Standard Response Block . . . . . . . . . . 25 4.4.3. Appending Standard Response Block . . . . . . . . . . 23
4.5. Proxying Mtrace2 Query . . . . . . . . . . . . . . . . . . 25 4.5. Proxying Mtrace2 Query . . . . . . . . . . . . . . . . . 24
4.6. Hiding Information . . . . . . . . . . . . . . . . . . . . 26 4.6. Hiding Information . . . . . . . . . . . . . . . . . . . 24
5. Client Behavior . . . . . . . . . . . . . . . . . . . . . . . 26 5. Client Behavior . . . . . . . . . . . . . . . . . . . . . . . 25
5.1. Sending Mtrace2 Query . . . . . . . . . . . . . . . . . . 26 5.1. Sending Mtrace2 Query . . . . . . . . . . . . . . . . . . 25
5.1.1. Destination Address . . . . . . . . . . . . . . . . . 26 5.1.1. Destination Address . . . . . . . . . . . . . . . . . 25
5.1.2. Source Address . . . . . . . . . . . . . . . . . . . . 26 5.1.2. Source Address . . . . . . . . . . . . . . . . . . . 25
5.2. Determining the Path . . . . . . . . . . . . . . . . . . . 26 5.2. Determining the Path . . . . . . . . . . . . . . . . . . 25
5.3. Collecting Statistics . . . . . . . . . . . . . . . . . . 27 5.3. Collecting Statistics . . . . . . . . . . . . . . . . . . 25
5.4. Last Hop Router (LHR) . . . . . . . . . . . . . . . . . . 27 5.4. Last Hop Router (LHR) . . . . . . . . . . . . . . . . . . 25
5.5. First Hop Router (FHR) . . . . . . . . . . . . . . . . . . 27 5.5. First Hop Router (FHR) . . . . . . . . . . . . . . . . . 26
5.6. Broken Intermediate Router . . . . . . . . . . . . . . . . 27 5.6. Broken Intermediate Router . . . . . . . . . . . . . . . 26
5.7. Non-Supported Router . . . . . . . . . . . . . . . . . . . 28 5.7. Non-Supported Router . . . . . . . . . . . . . . . . . . 26
5.8. Mtrace2 Termination . . . . . . . . . . . . . . . . . . . 28 5.8. Mtrace2 Termination . . . . . . . . . . . . . . . . . . . 27
5.8.1. Arriving at Source . . . . . . . . . . . . . . . . . . 28 5.8.1. Arriving at Source . . . . . . . . . . . . . . . . . 27
5.8.2. Fatal Error . . . . . . . . . . . . . . . . . . . . . 28 5.8.2. Fatal Error . . . . . . . . . . . . . . . . . . . . . 27
5.8.3. No Upstream Router . . . . . . . . . . . . . . . . . . 28 5.8.3. No Upstream Router . . . . . . . . . . . . . . . . . 27
5.8.4. Reply Timeout . . . . . . . . . . . . . . . . . . . . 28 5.8.4. Reply Timeout . . . . . . . . . . . . . . . . . . . . 27
5.9. Continuing after an Error . . . . . . . . . . . . . . . . 28 5.9. Continuing after an Error . . . . . . . . . . . . . . . . 27
6. Protocol-Specific Considerations . . . . . . . . . . . . . . . 29 6. Protocol-Specific Considerations . . . . . . . . . . . . . . 28
6.1. PIM-SM . . . . . . . . . . . . . . . . . . . . . . . . . . 29 6.1. PIM-SM . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.2. Bi-Directional PIM . . . . . . . . . . . . . . . . . . . . 29 6.2. Bi-Directional PIM . . . . . . . . . . . . . . . . . . . 28
6.3. PIM-DM . . . . . . . . . . . . . . . . . . . . . . . . . . 30 6.3. PIM-DM . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.4. IGMP/MLD Proxy . . . . . . . . . . . . . . . . . . . . . . 30 6.4. IGMP/MLD Proxy . . . . . . . . . . . . . . . . . . . . . 29
7. Problem Diagnosis . . . . . . . . . . . . . . . . . . . . . . 30 7. Problem Diagnosis . . . . . . . . . . . . . . . . . . . . . . 29
7.1. Forwarding Inconsistencies . . . . . . . . . . . . . . . . 30 7.1. Forwarding Inconsistencies . . . . . . . . . . . . . . . 29
7.2. TTL or Hop Limit Problems . . . . . . . . . . . . . . . . 30 7.2. TTL or Hop Limit Problems . . . . . . . . . . . . . . . . 29
7.3. Packet Loss . . . . . . . . . . . . . . . . . . . . . . . 30 7.3. Packet Loss . . . . . . . . . . . . . . . . . . . . . . . 29
7.4. Link Utilization . . . . . . . . . . . . . . . . . . . . . 31 7.4. Link Utilization . . . . . . . . . . . . . . . . . . . . 30
7.5. Time Delay . . . . . . . . . . . . . . . . . . . . . . . . 31 7.5. Time Delay . . . . . . . . . . . . . . . . . . . . . . . 30
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 32 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 30
8.1. Forwarding Codes . . . . . . . . . . . . . . . . . . . . . 32 8.1. Forwarding Codes . . . . . . . . . . . . . . . . . . . . 30
8.2. UDP Destination Port . . . . . . . . . . . . . . . . . . . 32 8.2. UDP Destination Port . . . . . . . . . . . . . . . . . . 31
9. Security Considerations . . . . . . . . . . . . . . . . . . . 32 9. Security Considerations . . . . . . . . . . . . . . . . . . . 31
9.1. Addresses in Mtrace2 Header . . . . . . . . . . . . . . . 32 9.1. Addresses in Mtrace2 Header . . . . . . . . . . . . . . . 31
9.2. Topology Discovery . . . . . . . . . . . . . . . . . . . . 32 9.2. Topology Discovery . . . . . . . . . . . . . . . . . . . 31
9.3. Characteristics of Multicast Channel . . . . . . . . . . . 32 9.3. Characteristics of Multicast Channel . . . . . . . . . . 31
9.4. Limiting Query/Request Rates . . . . . . . . . . . . . . . 33 9.4. Limiting Query/Request Rates . . . . . . . . . . . . . . 31
9.5. Limiting Reply Rates . . . . . . . . . . . . . . . . . . . 33 9.5. Limiting Reply Rates . . . . . . . . . . . . . . . . . . 31
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 33 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 32
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 33 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 32
11.1. Normative References . . . . . . . . . . . . . . . . . . . 33 11.1. Normative References . . . . . . . . . . . . . . . . . . 32
11.2. Informative References . . . . . . . . . . . . . . . . . . 34 11.2. Informative References . . . . . . . . . . . . . . . . . 33
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 34 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33
1. Introduction 1. Introduction
Given a multicast distribution tree, tracing from a multicast source Given a multicast distribution tree, tracing from a multicast source
to a receiver is difficult, since we do not know which branch of the to a receiver is difficult, since we do not know which branch of the
multicast tree the receiver lies. This means that we have to flood multicast tree the receiver lies. This means that we have to flood
the whole tree to find the path from a source to a receiver. On the the whole tree to find the path from a source to a receiver. On the
other hand, walking up the tree from a receiver to a source is easy, other hand, walking up the tree from a receiver to a source is easy,
as most existing multicast routing protocols know the upstream router as most existing multicast routing protocols know the upstream router
for each source. Tracing from a receiver to a source can involve for each source. Tracing from a receiver to a source can involve
only the routers on the direct path. only the routers on the direct path.
This document specifies the multicast traceroute facility named This document specifies the multicast traceroute facility named
Mtrace version 2 or Mtrace2 which allows the tracing of an IP Mtrace version 2 or Mtrace2 which allows the tracing of an IP
multicast routing path. Mtrace2 is usually initiated from a Mtrace2 multicast routing path. Mtrace2 is usually initiated from a Mtrace2
client towards a specified source, or a Rendezvous Point (RP) if no client towards a specified source, or a Rendezvous Point (RP) if no
source address is specified. RP is a special router where the source source address is specified. RP is a special router where the source
and receiver meet in PIM-SM [1]. Moreover, Mtrace2 provides and receiver meet in PIM-SM [5]. Moreover, Mtrace2 provides
additional information such as the packet rates and losses, as well additional information such as the packet rates and losses, as well
as other diagnosis information. Especially, Mtrace2 can be used for as other diagnosis information. Especially, Mtrace2 can be used for
the following purposes: the following purposes:
o To trace the path that a packet would take from a source to a o To trace the path that a packet would take from a source to a
receiver. receiver.
o To isolate packet loss problems (e.g., congestion). o To isolate packet loss problems (e.g., congestion).
o To isolate configuration problems (e.g., TTL threshold). o To isolate configuration problems (e.g., TTL threshold).
Figure 1 shows a typical case on how Mtrace2 is used. FHR represents Figure 1 shows a typical case on how Mtrace2 is used. FHR represents
the first-hop router, LHR represents the last-hop router, and the the first-hop router, LHR represents the last-hop router, and the
arrow lines represent the Mtrace2 messages that are sent from one arrow lines represent the Mtrace2 messages that are sent from one
node to another. The numbers before the Mtrace2 messages represent node to another. The numbers before the Mtrace2 messages represent
the sequence of the messages that would happen. Source, Receiver and the sequence of the messages that would happen. Source, Receiver and
Mtrace2 client are typically a host on the Internet. Mtrace2 client are typically a host on the Internet.
2. Request 2. Request 2. Request 2. Request
+----+ +----+ +----+ +----+
| | | | | | | |
v | v | v | v |
+--------+ +-----+ +-----+ +----------+ +--------+ +-----+ +-----+ +----------+
| Source |----| FHR |----- The Internet -----| LHR |----| Receiver | | Source |----| FHR |----- The Internet -----| LHR |----| Receiver |
+--------+ +-----+ | +-----+ +----------+ +--------+ +-----+ | +-----+ +----------+
\ | ^ \ | ^
\ | / \ | /
\ | / \ | /
\ | / \ | /
3. Reply \ | / 1. Query 3. Reply \ | / 1. Query
\ | / \ | /
\ | / \ | /
\ +---------+ / \ +---------+ /
v | Mtrace2 |/ v | Mtrace2 |/
| client | | client |
+---------+ +---------+
Figure 1 Figure 1
When an Mtrace2 client initiates a multicast trace anywhere on the When an Mtrace2 client initiates a multicast trace anywhere on the
Internet, it sends an Mtrace2 Query packet to the LHR for a multicast Internet, it sends an Mtrace2 Query packet to the LHR for a multicast
group and a source address. The LHR turns the Query packet into a group and a source address. The LHR turns the Query packet into a
Request, appends a standard response block containing its interface Request, appends a standard response block containing its interface
addresses and packet statistics to the Request packet, then forwards addresses and packet statistics to the Request packet, then forwards
the packet towards the source. The Request packet is either the packet towards the source. The Request packet is either
unicasted to its upstream router towards the source, or multicasted unicasted to its upstream router towards the source, or multicasted
to the group if the upsteam router's IP address is not known. In a to the group if the upstream router's IP address is not known. In a
similar fashion, each router along the path to the source appends a similar fashion, each router along the path to the source appends a
standard response block to the end of the Request packet before standard response block to the end of the Request packet before
forwarding it to its upstream router. When the FHR receives the forwarding it to its upstream router. When the FHR receives the
Request packet, it appends its own standard response block, turns the Request packet, it appends its own standard response block, turns the
Request packet into a Reply, and unicasts the Reply back to the Request packet into a Reply, and unicasts the Reply back to the
Mtrace2 client. Mtrace2 client.
The Mtrace2 Reply may be returned before reaching the FHR if it The Mtrace2 Reply may be returned before reaching the FHR if it
reaches the RP first, or a fatal error condition such as "no route" reaches the RP first, or a fatal error condition such as "no route"
is encountered along the path, or the hop count is exceeded. is encountered along the path, or the hop count is exceeded.
skipping to change at page 6, line 20 skipping to change at page 5, line 44
Mtrace2 supports both IPv4 and IPv6. Unlike the previous version of Mtrace2 supports both IPv4 and IPv6. Unlike the previous version of
Mtrace, which implements its query and response as IGMP messages [8], Mtrace, which implements its query and response as IGMP messages [8],
all Mtrace2 messages are UDP-based. Although the packet formats of all Mtrace2 messages are UDP-based. Although the packet formats of
IPv4 and IPv6 Mtrace2 are different because of the address families, IPv4 and IPv6 Mtrace2 are different because of the address families,
the syntax between them is similar. the syntax between them is similar.
2. Terminology 2. Terminology
In this document, the key words "MUST", "MUST NOT", "REQUIRED", In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" are to be interpreted as described in RFC 2119 [2], and "OPTIONAL" are to be interpreted as described in RFC 2119 [1],
and indicate requirement levels for compliant Mtrace2 and indicate requirement levels for compliant Mtrace2
implementations. implementations.
2.1. Definitions 2.1. Definitions
Since Mtrace2 Queries and Requests flow in the opposite direction to Since Mtrace2 Queries and Requests flow in the opposite direction to
the data flow, we refer to "upstream" and "downstream" with respect the data flow, we refer to "upstream" and "downstream" with respect
to data, unless explicitly specified. to data, unless explicitly specified.
Incoming interface Incoming interface
The interface on which data is expected to arrive from the The interface on which data is expected to arrive from the
specified source and group. specified source and group.
Outgoing interface Outgoing interface
The interface to which data from the source or RP is expected to The interface to which data from the source or RP is expected to
skipping to change at page 7, line 6 skipping to change at page 6, line 32
First-hop router (FHR) First-hop router (FHR)
The router that is directly connected to the source the Mtrace2 The router that is directly connected to the source the Mtrace2
Query specifies. Query specifies.
Last-hop router (LHR) Last-hop router (LHR)
The router that is directly connected to the receivers. It is The router that is directly connected to the receivers. It is
also the router that receives the Mtrace2 Query from an Mtrace2 also the router that receives the Mtrace2 Query from an Mtrace2
client. client.
Group state Group state
It is the state a shared-tree protocol, such as PIM-SM [1], uses It is the state a shared-tree protocol, such as PIM-SM [5], uses
to choose the upstream router towards the RP for the specified to choose the upstream router towards the RP for the specified
group. In this state, source-specific state is not available for group. In this state, source-specific state is not available for
the corresponding group address on the router. the corresponding group address on the router.
Source-specific state Source-specific state
It is the state that is used to choose the path towards the source It is the state that is used to choose the path towards the source
for the specified source and group. for the specified source and group.
ALL-[protocol]-ROUTERS.MCAST.NET ALL-[protocol]-ROUTERS.MCAST.NET
It is a link-local multicast address for multicast routers to It is a link-local multicast address for multicast routers to
communicate with their adjacent routers that are running the same communicate with their adjacent routers that are running the same
routing protocol. For instance, the address of ALL-PIM- routing protocol. For instance, the address of ALL-PIM-
ROUTERS.MCAST.NET [1] is '224.0.0.13' for IPv4 and 'ff02::d' for ROUTERS.MCAST.NET [5] is '224.0.0.13' for IPv4 and 'ff02::d' for
IPv6. IPv6.
3. Packet Formats 3. Packet Formats
This section describes the details of the packet formats for Mtrace2 This section describes the details of the packet formats for Mtrace2
messages. messages.
All Mtrace2 messages are encoded in TLV format (see Section 3.1). If All Mtrace2 messages are encoded in TLV format (see Section 3.1). If
an implementation receives an unknown TLV, it SHOULD ignored and an implementation receives an unknown TLV, it SHOULD ignored and
silently discarded the unknown TLV. If the length of a TLV exceeds silently discarded the unknown TLV. If the length of a TLV exceeds
the length specified in the TLV, the TLV SHOULD be accepted; however, the length specified in the TLV, the TLV SHOULD be accepted; however,
any additional data after the TLV SHOULD be ignored. any additional data after the TLV SHOULD be ignored.
All Mtrace2 messages are UDP packets. For IPv4, Mtrace2 Query and All Mtrace2 messages are UDP packets. For IPv4, Mtrace2 Query and
Request messages MUST NOT be fragmented. For IPv6, the packet size Request messages MUST NOT be fragmented. For IPv6, the packet size
for the Mtrace2 messages MUST NOT exceed 1280 bytes, which is the for the Mtrace2 messages MUST NOT exceed 1280 bytes, which is the
smallest MTU for an IPv6 interface [3]. The source port is uniquely smallest MTU for an IPv6 interface [2]. The source port is uniquely
selected by the local host operating system. The destination port is selected by the local host operating system. The destination port is
the IANA reserved Mtrace2 port number (see Section 8). All Mtrace2 the IANA reserved Mtrace2 port number (see Section 8). All Mtrace2
messages MUST have a valid UDP checksum. messages MUST have a valid UDP checksum.
Additionally, Mtrace2 supports both IPv4 and IPv6, but not mixed. Additionally, Mtrace2 supports both IPv4 and IPv6, but not mixed.
For example, if an Mtrace2 Query or Reply message arrives in as an For example, if an Mtrace2 Query or Request message arrives in as an
IPv4 packet, all addresses specified in the Mtrace2 messages MUST be IPv4 packet, all addresses specified in the Mtrace2 messages MUST be
IPv4 as well. Same rule applies to IPv6 Mtrace2 messages. IPv4 as well. Same rule applies to IPv6 Mtrace2 messages.
3.1. Mtrace2 TLV format 3.1. Mtrace2 TLV format
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Value .... | | Type | Length | Value .... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: 8 bits Type: 8 bits
Describes the format of the Value field. For all the available Describes the format of the Value field. For all the available
types, please see Section 3.2 types, please see Section 3.2
Length: 16 bits Length: 16 bits
Length of Type, Length, and Value fields in octets. Minimum Length of Type, Length, and Value fields in octets. Minimum
length required is 6 octets. The maximum TLV length is not length required is 6 octets. The maximum TLV length is not
defined; however the entired Mtrace2 packet length should not defined; however the entire Mtrace2 packet length should not
exceeed the available MTU. exceed the available MTU.
Value: variable length Value: variable length
The format is based on the Type value. The length of the value The format is based on the Type value. The length of the value
field is Length field minus 3. All reserved fields in the Value field is Length field minus 3. All reserved fields in the Value
field MUST be transmitted as zeros and ignored on receipt. field MUST be transmitted as zeros and ignored on receipt.
3.2. Defined TLVs 3.2. Defined TLVs
The following TLV Types are defined: The following TLV Types are defined:
Code Type Code Type
==== ================================ ==== ================================
0x01 Mtrace2 Query 0x01 Mtrace2 Query
0x02 Mtrace2 Request 0x02 Mtrace2 Request
0x03 Mtrace2 Reply 0x03 Mtrace2 Reply
0x04 Mtrace2 Standard Response Block 0x04 Mtrace2 Standard Response Block
0x05 Mtrace2 Augmented Response Block 0x05 Mtrace2 Augmented Response Block
0x06 Mtrace2 Extended Query Block 0x06 Mtrace2 Extended Query Block
Each Mtrace2 message MUST begin with either a Query, Request or Reply Each Mtrace2 message MUST begin with either a Query, Request or Reply
TLV. The first TLV determines the type of each Mtrace2 message. TLV. The first TLV determines the type of each Mtrace2 message.
Following this TLV, there can be a sequence of optional Extended Following a Query TLV, there can be a sequence of optional Extended
Query Blocks. In the case of the Request and Reply message, it is Query Blocks. In the case of a Request or a Reply TLV, it is then
then followed by a sequence of Standard Response Blocks, each from a followed by a sequence of Standard Response Blocks, each from a
multicast router on the path towards the source or the RP. In the multicast router on the path towards the source or the RP. In the
case more information is needed, a Standard Response Block can be case more information is needed, a Standard Response Block can be
followed by one or multiple Augmented Response Blocks. followed by one or multiple Augmented Response Blocks.
We will describe each message type in details in the next few We will describe each message type in details in the next few
sections. sections.
3.2.1. Mtrace2 Query 3.2.1. Mtrace2 Query
An Mtrace2 query is usually originated by an Mtrace2 client which An Mtrace2 Query is usually originated by an Mtrace2 client which
sends an Mtrace2 Query message to the LHR. When tracing towards the sends an Mtrace2 Query message to the LHR. When tracing towards the
source or the RP, the intermediate routers MUST NOT modify the Query source or the RP, the intermediate routers MUST NOT modify the Query
message except the Type field. message except the Type field.
An Mtrace2 Query message is shown as follows: An Mtrace2 Query message is shown as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | # Hops | | Type | Length | # Hops |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Multicast Address | | Multicast Address |
| | | |
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
| | | |
| Source Address | | Source Address |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Mtrace2 Client Address | | Mtrace2 Client Address |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Query ID | Client Port # | | Query ID | Client Port # |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2 Figure 2
# Hops: 8 bits # Hops: 8 bits
This field specifies the maximum number of hops that the Mtrace2 This field specifies the maximum number of hops that the Mtrace2
client wants to trace. If there are some error conditions in the client wants to trace. If there are some error conditions in the
middle of the path that prevent an Mtrace2 Reply from being middle of the path that prevent an Mtrace2 Reply from being
received by the client, the client MAY issues another Mtrace2 received by the client, the client MAY issues another Mtrace2
Query with the lower number of hops until it receives a Reply from Query with the lower number of hops until it receives a Reply.
the FHR.
Multicast Address: 32 bits or 128 bits Multicast Address: 32 bits or 128 bits
This field specifies an IPv4 or IPv6 address, which can be either: This field specifies an IPv4 or IPv6 address, which can be either:
m-1: a multicast group address to be traced; or, m-1: a multicast group address to be traced; or,
m-2: all 1's in case of IPv4 or the unspecified address (::) in m-2: all 1's in case of IPv4 or the unspecified address (::) in
case of IPv6 if no group-specific information is desired. case of IPv6 if no group-specific information is desired.
Source Address: 32 bits or 128 bits Source Address: 32 bits or 128 bits
skipping to change at page 10, line 37 skipping to change at page 10, line 5
Mtrace2 Reply will be sent to this address. Mtrace2 Reply will be sent to this address.
Query ID: 16 bits Query ID: 16 bits
This field is used as a unique identifier for this Mtrace2 Query This field is used as a unique identifier for this Mtrace2 Query
so that duplicate or delayed Reply messages may be detected. so that duplicate or delayed Reply messages may be detected.
Client Port #: 16 bits Client Port #: 16 bits
This field specifies the destination UDP port number for receiving This field specifies the destination UDP port number for receiving
the Mtrace2 Reply packet. the Mtrace2 Reply packet.
3.2.2. Mtrace2 Extended Query Block 3.2.2. Mtrace2 Request
There may be a sequence of optional Extended Query Blocks that follow
an Mtrace2 Query to further specify any information needed for the
Query. For example, an Mtrace2 client might be interested in tracing
the path the specified source and group would take based on a certain
topology. In which case, the client can pass in the multi-topology
ID as the Value for an Extended Query Type (see below). The Extended
Query Type is extensible and the behavior of the new types will be
addressed by seperate documents.
The Mtrace2 Extended Query Block is formatted as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | MBZ |T|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extended Query Type | Value .... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MBZ: 7 bits
This field must be zeroed on transmission and ignored on
reception.
T-bit (Transitive Attribute): 1 bit
If the TLV type is unrecognized by the receiving router, then this
TLV is either discarded or forwarded along with the Query,
depending on the value of this bit. If this bit is set, then the
router MUST forward this TLV. If this bit is clear, the router
MUST send an mtrace2 Reply with an UNKNOWN_QUERY error.
Extended Query Type: 16 bits
This field specifies the type of the Extended Query Block.
Value: 16 bits
This field specifies the value of this Extended Query.
3.2.3. Mtrace2 Request
The format of an Mtrace2 Request message is similar to an Mtrace2 The format of an Mtrace2 Request message is similar to an Mtrace2
Query except the Type field is 0x02. Query except the Type field is 0x02.
When a LHR receives an Mtrace2 Query message, it would turn the Query When a LHR receives an Mtrace2 Query message, it would turn the Query
into a Request by changing the Type field of the Query from 0x01 to into a Request by changing the Type field of the Query from 0x01 to
0x02. The LHR would then append an Mtrace2 Standard Response Block 0x02. The LHR would then append an Mtrace2 Standard Response Block
(see Section 3.2.5) of its own to the Request message before sending (see Section 3.2.4) of its own to the Request message before sending
it upstream. The upstream routers would do the same without changing it upstream. The upstream routers would do the same without changing
the Type field until one of them is ready to send a Reply. the Type field until one of them is ready to send a Reply.
3.2.4. Mtrace2 Reply 3.2.3. Mtrace2 Reply
The format of an Mtrace2 Reply message is similar to an Mtrace2 Query The format of an Mtrace2 Reply message is similar to an Mtrace2 Query
except the Type field is 0x03. except the Type field is 0x03.
When a FHR or a RP receives an Mtrace2 Request message which is When a FHR or a RP receives an Mtrace2 Request message which is
destined to itself, it would append an Mtrace2 Standard Response destined to itself, it would append an Mtrace2 Standard Response
Block (see Section 3.2.5) of its own to the Request message. Next, Block (see Section 3.2.4) of its own to the Request message. Next,
it would turn the Request message into a Reply by changing the Type it would turn the Request message into a Reply by changing the Type
field of the Request from 0x02 to 0x03. The Reply message would then field of the Request from 0x02 to 0x03. The Reply message would then
be unicated to the Mtrace2 client specified in the Mtrace2 Client be unicasted to the Mtrace2 client specified in the Mtrace2 Client
Address field. Address field.
There are a number of cases an intermediate router might return a There are a number of cases an intermediate router might return a
Reply before a Request reaches the FHR or the RP. See Section 4.1.1, Reply before a Request reaches the FHR or the RP. See Section 4.1.1,
Section 4.2.2, Section 4.3.3, and Section 4.5 for more details. Section 4.2.2, Section 4.3.3, and Section 4.5 for more details.
3.2.5. IPv4 Mtrace2 Standard Response Block 3.2.4. IPv4 Mtrace2 Standard Response Block
This section describes the message format of an IPv4 Mtrace2 Standard This section describes the message format of an IPv4 Mtrace2 Standard
Response Block. The Type field is 0x04. Response Block. The Type field is 0x04.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | MBZ | | Type | Length | MBZ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Query Arrival Time | | Query Arrival Time |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Incoming Interface Address | | Incoming Interface Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Outgoing Interface Address | | Outgoing Interface Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Upstream Router Address | | Upstream Router Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. Input packet count on incoming interface . . Input packet count on incoming interface .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. Output packet count on outgoing interface . . Output packet count on outgoing interface .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. Total number of packets for this source-group pair . . Total number of packets for this source-group pair .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rtg Protocol | Multicast Rtg Protocol | | Rtg Protocol | Multicast Rtg Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Fwd TTL | MBZ |S| Src Mask |Forwarding Code| | Fwd TTL | MBZ |S| Src Mask |Forwarding Code|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MBZ: 8 bits MBZ: 8 bits
This field must be zeroed on transmission and ignored on This field must be zeroed on transmission and ignored on
reception. reception.
Query Arrival Time: 32 bits Query Arrival Time: 32 bits
The Query Arrival Time is a 32-bit NTP timestamp specifying the The Query Arrival Time is a 32-bit NTP timestamp specifying the
arrival time of the Mtrace2 Query or Request packet at this arrival time of the Mtrace2 Query or Request packet at this
router. The 32-bit form of an NTP timestamp consists of the router. The 32-bit form of an NTP timestamp consists of the
middle 32 bits of the full 64-bit form; that is, the low 16 bits middle 32 bits of the full 64-bit form; that is, the low 16 bits
of the integer part and the high 16 bits of the fractional part. of the integer part and the high 16 bits of the fractional part.
The following formula converts from a UNIX timeval to a 32-bit NTP The following formula converts from a UNIX timeval to a 32-bit NTP
timestamp: timestamp:
query_arrival_time query_arrival_time
= (tv.tv_sec + 32384) << 16 + ((tv.tv_usec << 10) / 15625) = (tv.tv_sec + 32384) << 16 + ((tv.tv_usec << 10) / 15625)
The constant 32384 is the number of seconds from Jan 1, 1900 to The constant 32384 is the number of seconds from Jan 1, 1900 to
Jan 1, 1970 truncated to 16 bits. ((tv.tv_usec << 10) / 15625) is Jan 1, 1970 truncated to 16 bits. ((tv.tv_usec << 10) / 15625) is
a reduction of ((tv.tv_usec / 100000000) << 16). a reduction of ((tv.tv_usec / 100000000) << 16).
Note that Mtrace2 does not require all the routers on the path to Note that Mtrace2 does not require all the routers on the path to
have synchronized clocks in order to measure one-way latency. have synchronized clocks in order to measure one-way latency.
Additionally, Query Arrival Time is useful for measuring the Additionally, Query Arrival Time is useful for measuring the
packet rate. For example, suppose that a client issues two packet rate. For example, suppose that a client issues two
queries, and the corresponding requests R1 and R2 arrive at router queries, and the corresponding requests R1 and R2 arrive at router
X at time T1 and T2, then the client would be able to compute the X at time T1 and T2, then the client would be able to compute the
packet rate on router X by using the packet count information packet rate on router X by using the packet count information
skipping to change at page 13, line 46 skipping to change at page 12, line 19
Outgoing Interface Address: 32 bits Outgoing Interface Address: 32 bits
This field specifies the address of the interface on which packets This field specifies the address of the interface on which packets
from the source or the RP are expected to transmit towards the from the source or the RP are expected to transmit towards the
receiver, or 0 if unknown or unnumbered. This is also the address receiver, or 0 if unknown or unnumbered. This is also the address
of the interface on which the Mtrace2 Query or Request arrives. of the interface on which the Mtrace2 Query or Request arrives.
Upstream Router Address: 32 bits Upstream Router Address: 32 bits
This field specifies the address of the upstream router from which This field specifies the address of the upstream router from which
this router expects packets from this source. This may be a this router expects packets from this source. This may be a
multicast group (e.g. ALL-[protocol]-ROUTERS.MCAST.NET) if the multicast group (e.g. ALL-[protocol]-ROUTERS.MCAST.NET) if the
upstream router is not known because of the workings of the upstream router is not known because of the workings of the
multicast routing protocol. However, it should be 0 if the multicast routing protocol. However, it should be 0 if the
incoming interface address is unknown or unnumbered. incoming interface address is unknown or unnumbered.
Input packet count on incoming interface: 64 bits Input packet count on incoming interface: 64 bits
This field contains the number of multicast packets received for This field contains the number of multicast packets received for
all groups and sources on the incoming interface, or all 1's if no all groups and sources on the incoming interface, or all 1's if no
count can be reported. This counter may have the same value as count can be reported. This counter may have the same value as
ifHCInMulticastPkts from the IF-MIB [9] for this interface. ifHCInMulticastPkts from the IF-MIB [10] for this interface.
Output packet count on outgoing interface: 64 bit Output packet count on outgoing interface: 64 bit
This field contains the number of multicast packets that have been This field contains the number of multicast packets that have been
transmitted or queued for transmission for all groups and sources transmitted or queued for transmission for all groups and sources
on the outgoing interface, or all 1's if no count can be reported. on the outgoing interface, or all 1's if no count can be reported.
This counter may have the same value as ifHCOutMulticastPkts from This counter may have the same value as ifHCOutMulticastPkts from
the IF-MIB [9] for this interface. the IF-MIB [10] for this interface.
Total number of packets for this source-group pair: 64 bits Total number of packets for this source-group pair: 64 bits
This field counts the number of packets from the specified source This field counts the number of packets from the specified source
forwarded by the router to the specified group, or all 1's if no forwarded by the router to the specified group, or all 1's if no
count can be reported. If the S bit is set (see below), the count count can be reported. If the S bit is set (see below), the count
is for the source network, as specified by the Src Mask field (see is for the source network, as specified by the Src Mask field (see
below). If the S bit is set and the Src Mask field is 63, below). If the S bit is set and the Src Mask field is 63,
indicating no source-specific state, the count is for all sources indicating no source-specific state, the count is for all sources
sending to this group. This counter should have the same value as sending to this group. This counter should have the same value as
ipMcastRoutePkts from the IPMROUTE-STD-MIB [10] for this ipMcastRoutePkts from the IPMROUTE-STD-MIB [11] for this
forwarding entry. forwarding entry.
Rtg Protocol: 16 bits Rtg Protocol: 16 bits
This field describes the unicast routing protocol running between This field describes the unicast routing protocol running between
this router and the upstream router, and it is used to determine this router and the upstream router, and it is used to determine
the RPF interface for the specified source or RP. This value the RPF interface for the specified source or RP. This value
should have the same value as ipMcastRouteRtProtocol from the should have the same value as ipMcastRouteRtProtocol from the
IPMROUTE-STD-MIB [10] for this entry. If the router is not able IPMROUTE-STD-MIB [11] for this entry. If the router is not able
to obtain this value, all 0's must be specified. to obtain this value, all 0's must be specified.
Multicast Rtg Protocol: 16 bits Multicast Rtg Protocol: 16 bits
This field describes the multicast routing protocol in use between This field describes the multicast routing protocol in use between
the router and the upstream router. This value should have the the router and the upstream router. This value should have the
same value as ipMcastRouteProtocol from the IPMROUTE-STD-MIB [10] same value as ipMcastRouteProtocol from the IPMROUTE-STD-MIB [11]
for this entry. If the router cannot obtain this value, all 0's for this entry. If the router cannot obtain this value, all 0's
must be specified. must be specified.
Fwd TTL: 8 bits Fwd TTL: 8 bits
This field contains the TTL in which an Mtrace2 Request packet can This field contains the configured multicast TTL threshold, if
be forwarded towards the source or the RP. any, of the outgoing interface.
S: 1 bit S: 1 bit
If this bit is set, it indicates that the packet count for the If this bit is set, it indicates that the packet count for the
source-group pair is for the source network, as determined by source-group pair is for the source network, as determined by
masking the source address with the Src Mask field. masking the source address with the Src Mask field.
Src Mask: 7 bits Src Mask: 7 bits
This field contains the number of 1's in the netmask the router This field contains the number of 1's in the netmask the router
has for the source (i.e. a value of 24 means the netmask is has for the source (i.e. a value of 24 means the netmask is
0xffffff00). If the router is forwarding solely on group state, 0xffffff00). If the router is forwarding solely on group state,
skipping to change at page 16, line 47 skipping to change at page 14, line 29
0x0D UNKNOWN_QUERY A non-transitive Extended Query Type was 0x0D UNKNOWN_QUERY A non-transitive Extended Query Type was
received by a router which does not support received by a router which does not support
the type. the type.
0x80 FATAL_ERROR A fatal error is one where the router may 0x80 FATAL_ERROR A fatal error is one where the router may
know the upstream router but cannot forward know the upstream router but cannot forward
the message to it. the message to it.
0x81 NO_SPACE There was not enough room to insert another 0x81 NO_SPACE There was not enough room to insert another
Standard Response Block in the packet. Standard Response Block in the packet.
0x83 ADMIN_PROHIB Mtrace2 is administratively prohibited. 0x83 ADMIN_PROHIB Mtrace2 is administratively prohibited.
3.2.6. IPv6 Mtrace2 Standard Response Block 3.2.5. IPv6 Mtrace2 Standard Response Block
This section describes the message format of an IPv6 Mtrace2 Standard This section describes the message format of an IPv6 Mtrace2 Standard
Response Block. The Type field is also 0x04. Response Block. The Type field is also 0x04.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | MBZ | | Type | Length | MBZ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Query Arrival Time | | Query Arrival Time |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Incoming Interface ID | | Incoming Interface ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Outgoing Interface ID | | Outgoing Interface ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
* Local Address * * Local Address *
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
* Remote Address * * Remote Address *
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. Input packet count on incoming interface . . Input packet count on incoming interface .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. Output packet count on outgoing interface . . Output packet count on outgoing interface .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. Total number of packets for this source-group pair . . Total number of packets for this source-group pair .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rtg Protocol | Multicast Rtg Protocol | | Rtg Protocol | Multicast Rtg Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ 2 |S|Src Prefix Len |Forwarding Code| | MBZ 2 |S|Src Prefix Len |Forwarding Code|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MBZ: 8 bits MBZ: 8 bits
This field must be zeroed on transmission and ignored on This field must be zeroed on transmission and ignored on
reception. reception.
Query Arrival Time: 32 bits Query Arrival Time: 32 bits
Same definition as in IPv4. Same definition as in IPv4.
Incoming Interface ID: 32 bits Incoming Interface ID: 32 bits
This field specifies the interface ID on which packets from the This field specifies the interface ID on which packets from the
source or RP are expected to arrive, or 0 if unknown. This ID source or RP are expected to arrive, or 0 if unknown. This ID
should be the value taken from InterfaceIndex of the IF-MIB [9] should be the value taken from InterfaceIndex of the IF-MIB [10]
for this interface. for this interface.
Outgoing Interface ID: 32 bits Outgoing Interface ID: 32 bits
This field specifies the interface ID to which packets from the This field specifies the interface ID to which packets from the
source or RP are expected to transmit, or 0 if unknown. This ID source or RP are expected to transmit, or 0 if unknown. This ID
should be the value taken from InterfaceIndex of the IF-MIB [9] should be the value taken from InterfaceIndex of the IF-MIB [10]
for this interface for this interface
Local Address: 128 bits Local Address: 128 bits
This field specifies a global IPv6 address that uniquely This field specifies a global IPv6 address that uniquely
identifies the router. An unique local unicast address [11] identifies the router. An unique local unicast address [9] SHOULD
SHOULD NOT be used unless the router is only assigned link-local NOT be used unless the router is only assigned link-local and
and unique local addresses. If the router is only assigned link- unique local addresses. If the router is only assigned link-local
local addresses, its link-local address can be specified in this addresses, its link-local address can be specified in this field.
field.
Remote Address: 128 bits Remote Address: 128 bits
This field specifies the address of the upstream router, which, in This field specifies the address of the upstream router, which, in
most cases, is a link-local unicast address for the upstream most cases, is a link-local unicast address for the upstream
router. router.
Although a link-local address does not have enough information to Although a link-local address does not have enough information to
identify a node, it is possible to detect the upstream router with identify a node, it is possible to detect the upstream router with
the assistance of Incoming Interface ID and the current router the assistance of Incoming Interface ID and the current router
address (i.e., Local Address). address (i.e., Local Address).
Note that this may be a multicast group (e.g., ALL-[protocol]- Note that this may be a multicast group (e.g.,
ROUTERS.MCAST.NET) if the upstream router is not known because of ALL-[protocol]-ROUTERS.MCAST.NET) if the upstream router is not
the workings of a multicast routing protocol. However, it should known because of the workings of a multicast routing protocol.
be the unspecified address (::) if the incoming interface address However, it should be the unspecified address (::) if the incoming
is unknown. interface address is unknown.
Input packet count on incoming interface: 64 bits Input packet count on incoming interface: 64 bits
Same definition as in IPv4. Same definition as in IPv4.
Output packet count on outgoing interface: 64 bits Output packet count on outgoing interface: 64 bits
Same definition as in IPv4. Same definition as in IPv4.
Total number of packets for this source-group pair: 64 bits Total number of packets for this source-group pair: 64 bits
Same definition as in IPv4, except if the S bit is set (see Same definition as in IPv4, except if the S bit is set (see
below), the count is for the source network, as specified by the below), the count is for the source network, as specified by the
Src Prefix Len field. If the S bit is set and the Src Prefix Len Src Prefix Len field. If the S bit is set and the Src Prefix Len
field is 255, indicating no source-specific state, the count is field is 255, indicating no source-specific state, the count is
for all sources sending to this group. This counter should have for all sources sending to this group. This counter should have
the same value as ipMcastRoutePkts from the IPMROUTE-STD-MIB [10] the same value as ipMcastRoutePkts from the IPMROUTE-STD-MIB [11]
for this forwarding entry. for this forwarding entry.
Rtg Protocol: 16 bits Rtg Protocol: 16 bits
Same definition as in IPv4. Same definition as in IPv4.
Multicast Rtg Protocol: 16 bits Multicast Rtg Protocol: 16 bits
Same definition as in IPv4. Same definition as in IPv4.
MBZ 2: 15 bits MBZ 2: 15 bits
This field must be zeroed on transmission and ignored on This field must be zeroed on transmission and ignored on
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used to mask the source address. used to mask the source address.
Src Prefix Len: 8 bits Src Prefix Len: 8 bits
This field contains the prefix length this router has for the This field contains the prefix length this router has for the
source. If the router is forwarding solely on group state, this source. If the router is forwarding solely on group state, this
field is set to 255 (0xff). field is set to 255 (0xff).
Forwarding Code: 8 bits Forwarding Code: 8 bits
Same definition as in IPv4. Same definition as in IPv4.
3.2.7. Mtrace2 Augmented Response Block 3.2.6. Mtrace2 Augmented Response Block
In addition to the Standard Response Block, a multicast router on the In addition to the Standard Response Block, a multicast router on the
traced path can optionally add one or multiple Augmented Response traced path can optionally add one or multiple Augmented Response
Blocks before sending the Request to its upstream router. Blocks before sending the Request to its upstream router.
The Augmented Response Block is flexible for various purposes such as The Augmented Response Block is flexible for various purposes such as
providing diagnosis information (see Section 7) and protocol providing diagnosis information (see Section 7) and protocol
verification. It's Type field is 0x05, and its format is as follows: verification. Its Type field is 0x05, and its format is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | MBZ | | Type | Length | MBZ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Augmented Response Type | Value .... | | Augmented Response Type | Value .... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MBZ: 8 bits MBZ: 8 bits
This field must be zeroed on transmission and ignored on This field must be zeroed on transmission and ignored on
reception. reception.
Augmented Response Type: 16 bits Augmented Response Type: 16 bits
This field specifies the type of various responses from a This field specifies the type of various responses from a
multicast router that might need to communicate back to the multicast router that might need to communicate back to the
Mtrace2 client as well as the multicast routers on the traced Mtrace2 client as well as the multicast routers on the traced
path. path.
The Augmented Response Type is defined as follows: The Augmented Response Type is defined as follows:
Code Type Code Type
==== =============================================== ==== ===============================================
0x01 # of the returned Standard Response Blocks 0x01 # of the returned Standard Response Blocks
When the NO_SPACE error occurs on a router, the router should send When the NO_SPACE error occurs on a router, the router should send
the original Mtrace2 Request received from the downstream router the original Mtrace2 Request received from the downstream router
as a Reply back to the Mtrace2 client, and continue with a new as a Reply back to the Mtrace2 client, and continue with a new
Mtrace2 Request. In the new Request, the router would add a Mtrace2 Request. In the new Request, the router would add a
Standard Response Block followed by an Augmented Response Block Standard Response Block followed by an Augmented Response Block
with 0x01 as the Augmented Response Type, and the number of the with 0x01 as the Augmented Response Type, and the number of the
returned Mtrace2 Standard Response Blocks as the Value. returned Mtrace2 Standard Response Blocks as the Value.
Each upstream router would recognize the total number of hops the Each upstream router would recognize the total number of hops the
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This document only defines one Augmented Response Type in the This document only defines one Augmented Response Type in the
Augmented Response Block. The description on how to provide Augmented Response Block. The description on how to provide
diagnosis information using the Augmented Response Block is out of diagnosis information using the Augmented Response Block is out of
the scope of this document, and will be addressed in separate the scope of this document, and will be addressed in separate
documents. documents.
Value: variable length Value: variable length
The format is based on the Augmented Response Type value. The The format is based on the Augmented Response Type value. The
length of the value field is Length field minus 6. length of the value field is Length field minus 6.
3.2.7. Mtrace2 Extended Query Block
There may be a sequence of optional Extended Query Blocks that follow
an Mtrace2 Query to further specify any information needed for the
Query. For example, an Mtrace2 client might be interested in tracing
the path the specified source and group would take based on a certain
topology. In which case, the client can pass in the multi-topology
ID as the Value for an Extended Query Type (see below). The Extended
Query Type is extensible and the behavior of the new types will be
addressed by separate documents.
The Mtrace2 Extended Query Block's Type field is 0x06, and is
formatted as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | MBZ |T|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extended Query Type | Value .... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MBZ: 7 bits
This field must be zeroed on transmission and ignored on
reception.
T-bit (Transitive Attribute): 1 bit
If the TLV type is unrecognized by the receiving router, then this
TLV is either discarded or forwarded along with the Query,
depending on the value of this bit. If this bit is set, then the
router MUST forward this TLV. If this bit is clear, the router
MUST send an Mtrace2 Reply with an UNKNOWN_QUERY error.
Extended Query Type: 16 bits
This field specifies the type of the Extended Query Block.
Value: 16 bits
This field specifies the value of this Extended Query.
4. Router Behavior 4. Router Behavior
This section describes the router behavior in the context of Mtrace2 This section describes the router behavior in the context of Mtrace2
in details. in details.
4.1. Receiving Mtrace2 Query 4.1. Receiving Mtrace2 Query
An Mtrace2 Query message is an Mtrace2 message with no response An Mtrace2 Query message is an Mtrace2 message with no response
blocks filled in, and uses TLV type of 0x01. blocks filled in, and uses TLV type of 0x01.
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An Mtrace2 Request is an Mtrace2 message that uses TLV type of 0x02. An Mtrace2 Request is an Mtrace2 message that uses TLV type of 0x02.
With the exception of the LHR, whose Request was just converted from With the exception of the LHR, whose Request was just converted from
a Query, each Request received by a router should have at least one a Query, each Request received by a router should have at least one
Standard Response Block filled in. Standard Response Block filled in.
4.2.1. Request Packet Verification 4.2.1. Request Packet Verification
If the Mtrace2 Request does not come from an adjacent router, or if If the Mtrace2 Request does not come from an adjacent router, or if
the Request is not addressed to this router, or if the Request is the Request is not addressed to this router, or if the Request is
addressed to a multicast group which is not a link-scoped group (i.e. addressed to a multicast group which is not a link-scoped group (i.e.
224/24 for IPv4, FFx2::/16 [3] for IPv6), it MUST be silently
224/24 for IPv4, FFx2::/16 [4] for IPv6), it MUST be silently
ignored. GTSM [12] SHOULD be used by the router to determine whether ignored. GTSM [12] SHOULD be used by the router to determine whether
the router is adjacent or not. the router is adjacent or not.
If the sum of the number of the Standard Response Blocks in the If the sum of the number of the Standard Response Blocks in the
received Mtrace2 Request and the value of the Augmented Response Type received Mtrace2 Request and the value of the Augmented Response Type
of 0x01, if any, is equal or more than the # Hops in the Mtrace2 of 0x01, if any, is equal or more than the # Hops in the Mtrace2
Request, it MUST be silently ignored. Request, it MUST be silently ignored.
4.2.2. Request Normal Processing 4.2.2. Request Normal Processing
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interface. However, if the Incoming interface is unnumbered, the interface. However, if the Incoming interface is unnumbered, the
router can use one of its numbered interface address as the source router can use one of its numbered interface address as the source
address. address.
4.3.3. Appending Standard Response Block 4.3.3. Appending Standard Response Block
An Mtrace2 Request MUST be sent upstream towards the source or the RP An Mtrace2 Request MUST be sent upstream towards the source or the RP
after appending a Standard Response Block to the end of the received after appending a Standard Response Block to the end of the received
Mtrace2 Request. The Standard Response Block includes the multicast Mtrace2 Request. The Standard Response Block includes the multicast
states and statistics information of the router described in states and statistics information of the router described in
Section 3.2.5. Section 3.2.4.
If appending the Standard Response Block would make the Mtrace2 If appending the Standard Response Block would make the Mtrace2
Request packet longer than the MTU of the Incoming Interface, or, in Request packet longer than the MTU of the Incoming Interface, or, in
the case of IPv6, longer than 1280 bytes, the router MUST change the the case of IPv6, longer than 1280 bytes, the router MUST change the
Forwarding Code in the last Standard Response Block of the received Forwarding Code in the last Standard Response Block of the received
Mtrace2 Request into NO_SPACE. The router then turns the Request Mtrace2 Request into NO_SPACE. The router then turns the Request
into a Reply, and sends the Reply as described in Section 4.4. into a Reply, and sends the Reply as described in Section 4.4.
The router will continue with a new Request by copying from the old The router will continue with a new Request by copying from the old
Request excluding all the response blocks, followed by the previously Request excluding all the response blocks, followed by the previously
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Query or Request message, and terminates the trace. Query or Request message, and terminates the trace.
4.6. Hiding Information 4.6. Hiding Information
Information about a domain's topology and connectivity may be hidden Information about a domain's topology and connectivity may be hidden
from the Mtrace2 Requests. The Forwarding Code of INFO_HIDDEN may be from the Mtrace2 Requests. The Forwarding Code of INFO_HIDDEN may be
used to note that. For example, the incoming interface address and used to note that. For example, the incoming interface address and
packet count on the ingress router of a domain, and the outgoing packet count on the ingress router of a domain, and the outgoing
interface address and packet count on the egress router of the domain interface address and packet count on the egress router of the domain
can be specified as all 1's. Additionally, the source-group packet can be specified as all 1's. Additionally, the source-group packet
count (see Section 3.2.5 and Section 3.2.6) within the domain may be count (see Section 3.2.4 and Section 3.2.5) within the domain may be
all 1's if it is hidden. all 1's if it is hidden.
5. Client Behavior 5. Client Behavior
This section describes the behavior of an Mtrace2 client in details. This section describes the behavior of an Mtrace2 client in details.
5.1. Sending Mtrace2 Query 5.1. Sending Mtrace2 Query
An Mtrace2 client initiates an Mtrace2 Query by sending the Query to An Mtrace2 client initiates an Mtrace2 Query by sending the Query to
the LHR of interest. the LHR of interest.
skipping to change at page 29, line 13 skipping to change at page 27, line 47
will send back an Mtrace2 Reply to the Mtrace2 client, and continue will send back an Mtrace2 Reply to the Mtrace2 client, and continue
with a new Request (see Section 4.3.3). In which case, the Mtrace2 with a new Request (see Section 4.3.3). In which case, the Mtrace2
client may receive multiple Mtrace2 Replies from different routers client may receive multiple Mtrace2 Replies from different routers
along the path. When this happens, the client MUST treat them as a along the path. When this happens, the client MUST treat them as a
single Mtrace2 Reply message. single Mtrace2 Reply message.
If a trace times out, it is very likely that a router in the middle If a trace times out, it is very likely that a router in the middle
of the path does not support Mtrace2. That router's address will be of the path does not support Mtrace2. That router's address will be
in the Upstream Router field of the last Standard Response Block in in the Upstream Router field of the last Standard Response Block in
the last received Reply. A client may be able to determine (via the last received Reply. A client may be able to determine (via
mrinfo or SNMP [11][10]) a list of neighbors of the non-responding mrinfo or SNMP [9][11]) a list of neighbors of the non-responding
router. If desired, each of those neighbors could be probed to router. If desired, each of those neighbors could be probed to
determine the remainder of the path. Unfortunately, this heuristic determine the remainder of the path. Unfortunately, this heuristic
may end up with multiple paths, since there is no way of knowing what may end up with multiple paths, since there is no way of knowing what
the non-responding router's algorithm for choosing an upstream router the non-responding router's algorithm for choosing an upstream router
is. However, if all paths but one flow back towards the non- is. However, if all paths but one flow back towards the non-
responding router, it is possible to be sure that this is the correct responding router, it is possible to be sure that this is the correct
path. path.
6. Protocol-Specific Considerations 6. Protocol-Specific Considerations
skipping to change at page 29, line 39 skipping to change at page 28, line 24
When an Mtrace2 reaches a PIM-SM RP, and the RP does not forward the When an Mtrace2 reaches a PIM-SM RP, and the RP does not forward the
trace on, it means that the RP has not performed a source-specific trace on, it means that the RP has not performed a source-specific
join so there is no more state to trace. However, the path that join so there is no more state to trace. However, the path that
traffic would use if the RP did perform a source-specific join can be traffic would use if the RP did perform a source-specific join can be
traced by setting the trace destination to the RP, the trace source traced by setting the trace destination to the RP, the trace source
to the traffic source, and the trace group to 0. This Mtrace2 Query to the traffic source, and the trace group to 0. This Mtrace2 Query
may be unicasted to the RP. may be unicasted to the RP.
6.2. Bi-Directional PIM 6.2. Bi-Directional PIM
Bi-directional PIM [5] is a variant of PIM-SM that builds bi- Bi-directional PIM [6] is a variant of PIM-SM that builds bi-
directional shared trees connecting multicast sources and receivers. directional shared trees connecting multicast sources and receivers.
Along the bi-directional shared trees, multicast data is natively Along the bi-directional shared trees, multicast data is natively
forwarded from the sources to the Rendezvous Point Link (RPL), and forwarded from the sources to the Rendezvous Point Link (RPL), and
from which, to receivers without requiring source-specific state. In from which, to receivers without requiring source-specific state. In
contrast to PIM-SM, Bi-directional PIM always has the state to trace. contrast to PIM-SM, Bi-directional PIM always has the state to trace.
A Designated Forwarder (DF) for a given Rendezvous Point Address A Designated Forwarder (DF) for a given Rendezvous Point Address
(RPA) is in charge of forwarding downstream traffic onto its link, (RPA) is in charge of forwarding downstream traffic onto its link,
and forwarding upstream traffic from its link towards the RPL that and forwarding upstream traffic from its link towards the RPL that
the RPA belongs to. Hence Mtrace2 Reply reports DF addresses or RPA the RPA belongs to. Hence Mtrace2 Reply reports DF addresses or RPA
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appropriate last hop. appropriate last hop.
When traffic is flowing, PIM Dense Mode routers know whether or not When traffic is flowing, PIM Dense Mode routers know whether or not
they are the LHR for the link (because they won or lost an Assert they are the LHR for the link (because they won or lost an Assert
battle) and know who the upstream router is (because it won an Assert battle) and know who the upstream router is (because it won an Assert
battle). Therefore, Mtrace2 is always able to follow the proper path battle). Therefore, Mtrace2 is always able to follow the proper path
when traffic is flowing. when traffic is flowing.
6.4. IGMP/MLD Proxy 6.4. IGMP/MLD Proxy
When an IGMP/MLD Proxy [6] receives an Mtrace2 Query packet on an When an IGMP/MLD Proxy [7] receives an Mtrace2 Query packet on an
incoming interface, it notes a WRONG_IF in the Forwarding Code of the incoming interface, it notes a WRONG_IF in the Forwarding Code of the
last Standard Response Block (see Section 3.2.5), and sends the last Standard Response Block (see Section 3.2.4), and sends the
Mtrace2 Reply back to the Mtrace2 client. On the other hand, when an Mtrace2 Reply back to the Mtrace2 client. On the other hand, when an
Mtrace2 Query packet reaches an outgoing interface of the IGMP/MLD Mtrace2 Query packet reaches an outgoing interface of the IGMP/MLD
proxy, it is forwarded onto its incoming interface towards the proxy, it is forwarded onto its incoming interface towards the
upstream router. upstream router.
7. Problem Diagnosis 7. Problem Diagnosis
This section describes different scenarios Mtrace2 can be used to This section describes different scenarios Mtrace2 can be used to
diagnose the multicast problems. diagnose the multicast problems.
skipping to change at page 32, line 8 skipping to change at page 30, line 43
If the routers have synchronized clocks, it is possible to estimate If the routers have synchronized clocks, it is possible to estimate
propagation and queuing delay from the differences between the propagation and queuing delay from the differences between the
timestamps at successive hops. However, this delay includes control timestamps at successive hops. However, this delay includes control
processing overhead, so is not necessarily indicative of the delay processing overhead, so is not necessarily indicative of the delay
that data traffic would experience. that data traffic would experience.
8. IANA Considerations 8. IANA Considerations
The following new assignments can only be made via a Standards Action The following new assignments can only be made via a Standards Action
as specified in [7]. as specified in [4].
8.1. Forwarding Codes 8.1. Forwarding Codes
New Forwarding Codes must only be created by an RFC that modifies New Forwarding Codes must only be created by an RFC that modifies
this document's Section 3.2.5 and Section 3.2.6, fully describing the this document's Section 3.2.4 and Section 3.2.5, fully describing the
conditions under which the new Forwarding Code is used. The IANA may conditions under which the new Forwarding Code is used. The IANA may
act as a central repository so that there is a single place to look act as a central repository so that there is a single place to look
up Forwarding Codes and the document in which they are defined. up Forwarding Codes and the document in which they are defined.
8.2. UDP Destination Port 8.2. UDP Destination Port
The IANA should allocate UDP destination port for Mtrace2 upon The IANA should allocate UDP destination port for Mtrace2 upon
publication of the first RFC. publication of the first RFC.
9. Security Considerations 9. Security Considerations
This section addresses some of the security considerations related to This section addresses some of the security considerations related to
Mtrace2. Mtrace2.
9.1. Addresses in Mtrace2 Header 9.1. Addresses in Mtrace2 Header
An Mtrace2 header includes three addresses, source address, multicast An Mtrace2 header includes three addresses, source address, multicast
address, and Mtrace2 client address. These addresses MUST be address, and Mtrace2 client address. These addresses MUST be
congruent with the definition defined in Section 3.2.1 and forwarding congruent with the definition defined in Section 3.2.1 and forwarding
Mtrace2 messages having invalid addresses MUST be prohibited. For Mtrace2 messages having invalid addresses MUST be prohibited. For
instance, if Mtrace2 Client Address specified in an Mtrace header is instance, if Mtrace2 Client Address specified in an Mtrace2 header is
a multicast address, then a router that receives the Mtrace2 message a multicast address, then a router that receives the Mtrace2 message
MUST silently discard it. MUST silently discard it.
9.2. Topology Discovery 9.2. Topology Discovery
Mtrace2 can be used to discover any actively-used topology. If your Mtrace2 can be used to discover any actively-used topology. If your
network topology is a secret, Mtrace2 may be restricted at the border network topology is a secret, Mtrace2 may be restricted at the border
of your domain, using the ADMIN_PROHIB forwarding code. of your domain, using the ADMIN_PROHIB forwarding code.
9.3. Characteristics of Multicast Channel 9.3. Characteristics of Multicast Channel
skipping to change at page 33, line 42 skipping to change at page 32, line 27
give special thanks to Tatsuya Jinmei, Bill Fenner, and Steve Casner. give special thanks to Tatsuya Jinmei, Bill Fenner, and Steve Casner.
Also, extensive comments were received from David L. Black, Ronald Also, extensive comments were received from David L. Black, Ronald
Bonica, Yiqun Cai, Liu Hui, Bharat Joshi, Robert W. Kebler, Heidi Ou, Bonica, Yiqun Cai, Liu Hui, Bharat Joshi, Robert W. Kebler, Heidi Ou,
Pekka Savola, Shinsuke Suzuki, Dave Thaler, Achmad Husni Thamrin, and Pekka Savola, Shinsuke Suzuki, Dave Thaler, Achmad Husni Thamrin, and
Cao Wei. Cao Wei.
11. References 11. References
11.1. Normative References 11.1. Normative References
[1] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas, [1] Bradner, S., "Key words for use in RFCs to indicate
"Protocol Independent Multicast - Sparse Mode (PIM-SM): requirement levels", RFC 2119, March 1997.
Protocol Specification (Revised)", RFC 4601, August 2006.
[2] Bradner, S., "Key words for use in RFCs to indicate requirement [2] Deering, S. and R. Hinden, "Internet Protocol, Version 6
levels", RFC 2119, March 1997. (IPv6) Specification", RFC 2460, December 1998.
[3] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) [3] Hinden, R. and S. Deering, "IP Version 6 Addressing
Specification", RFC 2460, December 1998. Architecture", RFC 4291, February 2006.
[4] Hinden, R. and S. Deering, "IP Version 6 Addressing [4] Narten, T. and H. Alvestrand, "Guidelines for Writing an
Architecture", RFC 4291, February 2006. IANA Considerations Section in RFCs", RFC 5226, May 2008.
[5] Handley, M., Kouvelas, I., Speakman, T., and L. Vicisano, [5] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,
"Bidirectional Protocol Independent Multicast (BIDIR-PIM)", "Protocol Independent Multicast - Sparse Mode (PIM-SM):
RFC 5015, October 2007. Protocol Specification (Revised)", RFC 4601, August 2006.
[6] Fenner, B., He, H., Haberman, B., and H. Sandick, "Internet [6] Handley, M., Kouvelas, I., Speakman, T., and L. Vicisano,
Group Management Protocol (IGMP) / Multicast Listener Discovery "Bidirectional Protocol Independent Multicast (BIDIR-
(MLD)-Based Multicast Forwarding ("IGMP/MLD Proxying")", PIM)", RFC 5015, October 2007.
RFC 4605, August 2006.
[7] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA [7] Fenner, B., He, H., Haberman, B., and H. Sandick,
Considerations Section in RFCs", RFC 5226, May 2008. "Internet Group Management Protocol (IGMP) / Multicast
Listener Discovery (MLD)-Based Multicast Forwarding ("IGMP
/MLD Proxying")", RFC 4605, August 2006.
11.2. Informative References 11.2. Informative References
[8] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A. [8] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A.
Thyagarajan, "Internet Group Management Protocol, Version 3", Thyagarajan, "Internet Group Management Protocol, Version
RFC 3376, October 2002. 3", RFC 3376, October 2002.
[9] McCloghrie, K. and F. Kastenholz, "The Interfaces Group MIB", [9] Draves, R. and D. Thaler, "Default Router Preferences and
RFC 2863, June 2000. More-Specific Routes", RFC 4191, November 2005.
[10] McWalter, D., Thaler, D., and A. Kessler, "IP Multicast MIB", [10] McCloghrie, K. and F. Kastenholz, "The Interfaces Group
RFC 5132, December 2007. MIB", RFC 2863, June 2000.
[11] Draves, R. and D. Thaler, "Default Router Preferences and More- [11] McWalter, D., Thaler, D., and A. Kessler, "IP Multicast
Specific Routes", RFC 4191, November 2005. MIB", RFC 5132, December 2007.
[12] Gill, V., Heasley, J., Meyer, D., Savola, P., and C. Pignataro, [12] Gill, V., Heasley, J., Meyer, D., Savola, P., and C.
"The Generalized TTL Security Mechanism (GTSM)", RFC 5082, Pignataro, "The Generalized TTL Security Mechanism
October 2007. (GTSM)", RFC 5082, October 2007.
[13] Adams, A., Nicholas, J., and W. Siadak, "Protocol Independent [13] Adams, A., Nicholas, J., and W. Siadak, "Protocol
Multicast - Dense Mode (PIM-DM): Protocol Specification Independent Multicast - Dense Mode (PIM-DM): Protocol
(Revised)", RFC 3973, January 2005. Specification (Revised)", RFC 3973, January 2005.
Authors' Addresses Authors' Addresses
Hitoshi Asaeda Hitoshi Asaeda
National Institute of Information and Communications Technology National Institute of Information and Communications Technology
4-2-1 Nukui-Kitamachi 4-2-1 Nukui-Kitamachi
Koganei, Tokyo 184-8795 Koganei, Tokyo 184-8795
Japan Japan
Email: asaeda@nict.go.jp Email: asaeda@nict.go.jp
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