draft-ietf-pim-mtid-01.txt   draft-ietf-pim-mtid-02.txt 
PIM WG Yiqun Cai PIM WG Yiqun Cai
Internet Draft Heidi Ou Internet Draft Heidi Ou
Intended Status: Proposed Standard Intended Status: Proposed Standard
Expires: January 2, 2010 Cisco Systems, Inc. Expires: April 26, 2010 Cisco Systems, Inc.
July 2, 2009 October 26, 2009
PIM Multi-Topology ID (MT-ID) Join-Attribute PIM Multi-Topology ID (MT-ID) Join-Attribute
draft-ietf-pim-mtid-01.txt draft-ietf-pim-mtid-02.txt
Status of this Memo Status of this Memo
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Copyright Notice Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the Copyright (c) 2009 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Abstract Abstract
This document introduces a new type of PIM Join Attribute that This document introduces a new type of PIM Join Attribute that
extends PIM signaling to identify a topology that should be used when extends PIM signaling to identify a topology that should be used when
constructing a particular multicast distribution tree. constructing a particular multicast distribution tree.
Table of Contents Table of Contents
1 Specification of Requirements ...................... 2 1 Specification of Requirements ...................... 3
2 Introduction ....................................... 3 2 Introduction ....................................... 3
3 Functional Overview ................................ 3 3 Functional Overview ................................ 3
3.1 PIM RPF Topology ................................... 3 3.1 PIM RPF Topology ................................... 3
3.2 PIM MT-ID .......................................... 4 3.2 PIM MT-ID .......................................... 4
3.3 Applicability ...................................... 4 3.3 Applicability ...................................... 4
4 Protocol Specification of PIM MT-ID ................ 5 4 Protocol Specification of PIM MT-ID ................ 5
4.1 Sending PIM MT-ID Join Attribute ................... 5 4.1 PIM MT-ID Hello Option ............................. 5
4.2 Receiving PIM MT-ID Join Attribute ................. 5 4.2 PIM MT-ID Join Attribute ........................... 5
4.3 Validating PIM MT-ID Join Attribute ................ 6 4.2.1 Sending PIM MT-ID Join Attribute ................... 5
4.4 Conflict Resolution ................................ 6 4.2.2 Receiving PIM MT-ID Join Attribute ................. 6
4.4.1 Upstream Routers ................................... 6 4.2.3 Validating PIM MT-ID Join Attribute ................ 6
4.4.2 Downstream Routers ................................. 7 4.2.4 Conflict Resolution ................................ 6
5 PIM MT-ID Join Attribute TLV Format ................ 7 4.2.4.1 Upstream Routers ................................... 7
6 IANA Considerations ................................ 8 4.2.4.2 Downstream Routers ................................. 7
7 Security Considerations ............................ 8 5 Packet Format ...................................... 8
8 Acknowledgments .................................... 8 5.1 PIM MT-ID Hello Option ............................. 8
9 Authors' Addresses ................................. 8 5.2 PIM MT-ID Join Attribute TLV Format ................ 8
10 Normative References ............................... 9 6 IANA Considerations ................................ 9
11 Informative References ............................. 9 7 Security Considerations ............................ 9
8 Acknowledgments .................................... 9
9 Authors' Addresses ................................. 9
10 Normative References ............................... 10
11 Informative References ............................. 10
1. Specification of Requirements 1. Specification of Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2. Introduction 2. Introduction
Some unicast protocols, such as OSPF and IS-IS, allow a single Some unicast protocols, such as OSPF and IS-IS, allow a single
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Graft-ack, DF Election, Candidate-RP, and Bootstrap. As such, it can Graft-ack, DF Election, Candidate-RP, and Bootstrap. As such, it can
only be used to build shared or source trees for PIM SM/SSM and PIM- only be used to build shared or source trees for PIM SM/SSM and PIM-
bidir downstream. bidir downstream.
When this attribute is used in combination with RPF vectors defined When this attribute is used in combination with RPF vectors defined
in [RFC5496] [ID.ietf-l3vpn-2547bis-mcast], they are processed in [RFC5496] [ID.ietf-l3vpn-2547bis-mcast], they are processed
against the topology identified by the PIM MT-ID attribute. against the topology identified by the PIM MT-ID attribute.
4. Protocol Specification of PIM MT-ID 4. Protocol Specification of PIM MT-ID
4.1. Sending PIM MT-ID Join Attribute The change to the PIM protocol includes two pieces, PIM MT-ID Hello
Option and PIM MT-ID Join Attribute.
4.1. PIM MT-ID Hello Option
A router MUST include both PIM MT-ID and PIM Join Attribute Hello
Option in its PIM Hello packets if it supports functionality
described by this document.
4.2. PIM MT-ID Join Attribute
4.2.1. Sending PIM MT-ID Join Attribute
When a PIM router originates a PIM Join/Assert packet, it may choose When a PIM router originates a PIM Join/Assert packet, it may choose
to encode PIM MT-ID of the topology in which RPF lookup takes place to encode PIM MT-ID of the topology in which RPF lookup takes place
for the corresponding (*,G) or (S,G) entry. The chosen PIM MT-ID MUST for the corresponding (*,G) or (S,G) entry. The chosen PIM MT-ID MUST
be the one decided by local topology selection configuration if it be the one decided by local topology selection configuration if it
exists, or the one received from downstream routers after conflict exists, or the one received from downstream routers after conflict
resolution procedures are applied. resolution procedures are applied.
The following are the exceptions, The following are the exceptions,
- a router MUST NOT attach the attribute if PIM MT-ID is 0. The - a router MUST NOT attach the attribute if PIM MT-ID is 0. The
value of 0 is ignored on reception. value of 0 is ignored on reception.
- a router SHOULD NOT do so if the upstream router, or one of the - a router SHOULD NOT do so if the upstream router, or one of the
routers on the LAN does not include "PIM Join Attribute" option routers on the LAN does not include "PIM Join Attribute" or "PIM
in its Hello packets. MT-ID" option in its Hello packets.
- a router SHOULD NOT encode PIM MT-ID for pruned sources. If - a router SHOULD NOT encode PIM MT-ID for pruned sources. If
encoded, the value is ignored. encoded, the value is ignored.
4.2. Receiving PIM MT-ID Join Attribute 4.2.2. Receiving PIM MT-ID Join Attribute
When a PIM router receives a PIM MT-ID join attribute in a When a PIM router receives a PIM MT-ID join attribute in a
Join/Assert packet, it MUST perform the following, Join/Assert packet, it MUST perform the following,
- validate the attribute encoding. The detail is described in the - validate the attribute encoding. The detail is described in the
next section. next section.
- if the join attribute is valid, use the rules described in the - if the join attribute is valid, use the rules described in the
section "Conflict Resolution" to determine a PIM MT-ID to use. section "Conflict Resolution" to determine a PIM MT-ID to use.
- use the topology identified by the selected PIM MT-ID to perform - use the topology identified by the selected PIM MT-ID to perform
RPF lookup for the (*,G)/(S,G) entry unless a different topology RPF lookup for the (*,G)/(S,G) entry unless a different topology
is specified by a local configuration. The local configuration is specified by a local configuration. The local configuration
always takes precedence. always takes precedence.
4.3. Validating PIM MT-ID Join Attribute 4.2.3. Validating PIM MT-ID Join Attribute
An encoded PIM MT-ID join attribute is valid if all of the following An encoded PIM MT-ID join attribute is valid if all of the following
conditions are satisfied, conditions are satisfied,
- there is at most 1 PIM MT-ID attribute encoded. - there is at most 1 PIM MT-ID attribute encoded. If there are
multiple PIM MT-ID Join Attributes included, only the last one is
accepted.
- the length field must be 2 and the value must not be 0. - the length field must be 2 and the value must not be 0.
If an encoded PIM MT-ID join attribute is deemed invalid, it is If an encoded PIM MT-ID join attribute is deemed invalid, it is
silently ignored. The packet is processed as if the attribute were silently ignored. The packet is processed as if the attribute were
not present. not present.
It is important to note that, if the sender is not a PIM neighbor It is important to note that, if the sender is not a PIM neighbor
that has included "PIM Join Attribute" option in its Hello packets, that has included "PIM Join Attribute" or "PIM MT-ID" option in its
the encoding may still be considered valid by an implementation. Hello packets, the encoding may still be considered valid by an
implementation.
4.4. Conflict Resolution 4.2.4. Conflict Resolution
Depending on whether a PIM router is an upstream or a downstream Depending on whether a PIM router is an upstream or a downstream
router, the action it takes to resolve conflicting PIM MT-ID router, the action it takes to resolve conflicting PIM MT-ID
attributes differs. The detail is described below. attributes differs. The detail is described below.
4.4.1. Upstream Routers 4.2.4.1. Upstream Routers
If an upstream router has a local configuration that specifies a If an upstream router has a local configuration that specifies a
different topology than that from an incoming Join/Assert packet, different topology than that from an incoming Join/Assert packet,
including the case PIM MT-ID is not encoded in the incoming packet, including the case PIM MT-ID is not encoded in the incoming packet,
it is not considered a conflict. it is not considered a conflict.
A conflict occurs when a router doesn't have local topology selection A conflict occurs when a router doesn't have local topology selection
policy and it has received different PIM MT-ID from Join packets sent policy and it has received different PIM MT-ID from Join packets sent
by its downstream routers or Assert packets from another forwarding by its downstream routers or Assert packets from another forwarding
router on the LAN. router on the LAN.
It MUST be noted that the MT-ID value being considered for comparison
does not include the four reserved bits. That is, only the lower
order 12 bits are used in resolving conflicting attributes.
- if an upstream router receives different PIM MT-ID attributes - if an upstream router receives different PIM MT-ID attributes
from PIM Join packets, it MUST follow the rules specified in from PIM Join packets, it MUST follow the rules specified in
[RFC5384] to select one. The PIM MT-ID chosen will be the one [RFC5384] to select one. The PIM MT-ID chosen will be the one
encoded for its upstream neighbor. encoded for its upstream neighbor.
- if an upstream router receives a different PIM MT-ID attribute in - if an upstream router receives a different PIM MT-ID attribute in
an ASSERT packet, it MUST use the tie-breaker rules as specified an ASSERT packet, it MUST use the tie-breaker rules as specified
in [RFC4601] to determine an ASSERT winner. PIM MT-ID is not in [RFC4601] to determine an ASSERT winner. PIM MT-ID is not
considered in deciding a winner from Assert process. considered in deciding a winner from Assert process.
4.4.2. Downstream Routers 4.2.4.2. Downstream Routers
A conflict is detected by a downstream router when it sees a A conflict is detected by a downstream router when it sees a
different PIM MT-ID attribute from other routers on the LAN, different PIM MT-ID attribute from other routers on the LAN,
regardless of whether the router has local topology selection policy regardless of whether the router has local topology selection policy
or not. or not.
- if a downstream router sees different PIM MT-ID attributes from - if a downstream router sees different PIM MT-ID attributes from
PIM Join packets, it MUST follow the specification of [RFC4601] PIM Join packets, it MUST follow the specification of [RFC4601]
as if the attribute did not exist. For example, the router as if the attribute did not exist. For example, the router
suppresses its own Join packet if a Join for the same (S,G) is suppresses its own Join packet if a Join for the same (S,G) is
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The router MUST NOT use the rules specified in [RFC5384] to The router MUST NOT use the rules specified in [RFC5384] to
select a PIM MT-ID from Join packets sent by other downstream select a PIM MT-ID from Join packets sent by other downstream
routers. routers.
- if a downstream router sees its preferred upstream router loses - if a downstream router sees its preferred upstream router loses
in the ASSERT process, and the ASSERT winner uses a different PIM in the ASSERT process, and the ASSERT winner uses a different PIM
MT-ID, the downstream router SHOULD still choose the ASSERT MT-ID, the downstream router SHOULD still choose the ASSERT
winner as the RPF neighbour but it MUST NOT encode PIM MT-ID when winner as the RPF neighbour but it MUST NOT encode PIM MT-ID when
sending Join packets to it. sending Join packets to it.
5. PIM MT-ID Join Attribute TLV Format 5. Packet Format
5.1. PIM MT-ID Hello Option
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OptionType | OptionLength |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OptionValue |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- OptionType: to be assigned by IANA.
- OptionLength: 8
- OptionValue: There is none specified at this moment.
5.2. PIM MT-ID Join Attribute 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|F|E| Attr Type | Length |R R R R| Value | |F|E| Attr Type | Length |R R R R| Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- F bit: 0 Non-transitive Attribute. - F bit: 0 Non-transitive Attribute.
- E bit: As specified by [RFC5384] - E bit: As specified by [RFC5384]
- Attr Type: 3. - Attr Type: 3.
- Length: 2. - Length: 2.
- R: Reserved bits, 4 in total. - R: Reserved bits, 4 in total.
- Value: PIM MT-ID, 1 to 4095. - Value: PIM MT-ID, 1 to 4095. Range 2048 to 4095 are for
experimental and proprietary use.
6. IANA Considerations 6. IANA Considerations
A new PIM Hello Option type needs to be assigned.
A new PIM Join Attribute type needs to be assigned. 3 is proposed for A new PIM Join Attribute type needs to be assigned. 3 is proposed for
now. now.
7. Security Considerations 7. Security Considerations
As a type of PIM Join Attribute, the security considerations As a type of PIM Join Attribute, the security considerations
described in [RFC5384] apply here. Specifically, malicious alteration described in [RFC5384] apply here. Specifically, malicious alteration
of PIM MT-ID may cause the resiliency goals to be violated. of PIM MT-ID may cause the resiliency goals to be violated.
8. Acknowledgments 8. Acknowledgments
The authors would like to thank Eric Rosen, Ice Wijnands, Dino The authors would like to thank Eric Rosen, Ice Wijnands, Dino
Farinacci, Colby Barth and Les Ginsberg for their input. Farinacci, Colby Barth, Les Ginsberg and Dimitri Papadimitriou for
their input.
9. Authors' Addresses 9. Authors' Addresses
Yiqun Cai Yiqun Cai
Cisco Systems, Inc Cisco Systems, Inc
170 West Tasman Drive 170 West Tasman Drive
San Jose, CA 95134 San Jose, CA 95134
E-mail: ycai@cisco.com E-mail: ycai@cisco.com
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