draft-ietf-pim-mtid-02.txt   draft-ietf-pim-mtid-03.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: April 26, 2010 Cisco Systems, Inc. Expires: August 9, 2010 Cisco Systems, Inc.
October 26, 2009 February 9, 2010
PIM Multi-Topology ID (MT-ID) Join-Attribute PIM Multi-Topology ID (MT-ID) Join-Attribute
draft-ietf-pim-mtid-02.txt draft-ietf-pim-mtid-03.txt
Status of this Memo Status of this Memo
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Copyright Notice Copyright Notice
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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 ...................... 3 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 ...................................... 5
4 Protocol Specification of PIM MT-ID ................ 5 4 Protocol Specification of PIM MT-ID ................ 5
4.1 PIM MT-ID Hello Option ............................. 5 4.1 PIM MT-ID Hello Option ............................. 5
4.2 PIM MT-ID Join Attribute ........................... 5 4.2 PIM MT-ID Join Attribute ........................... 5
4.2.1 Sending PIM MT-ID Join Attribute ................... 5 4.2.1 Sending PIM MT-ID Join Attribute ................... 5
4.2.2 Receiving PIM MT-ID Join Attribute ................. 6 4.2.2 Receiving PIM MT-ID Join Attribute ................. 6
4.2.3 Validating PIM MT-ID Join Attribute ................ 6 4.2.3 Validating PIM MT-ID Join Attribute ................ 6
4.2.4 Conflict Resolution ................................ 6 4.2.4 Conflict Resolution ................................ 7
4.2.4.1 Upstream Routers ................................... 7 4.2.4.1 Conflict Resolution Rules For Upstream Routers ..... 7
4.2.4.2 Downstream Routers ................................. 7 4.2.4.2 Conflict Resolution Rules For Downstream Routers ... 7
5 Packet Format ...................................... 8 5 Packet Format ...................................... 8
5.1 PIM MT-ID Hello Option ............................. 8 5.1 PIM MT-ID Hello Option ............................. 8
5.2 PIM MT-ID Join Attribute TLV Format ................ 8 5.2 PIM MT-ID Join Attribute TLV Format ................ 8
6 IANA Considerations ................................ 9 6 IANA Considerations ................................ 9
7 Security Considerations ............................ 9 7 Security Considerations ............................ 9
8 Acknowledgments .................................... 9 8 Acknowledgments .................................... 9
9 Authors' Addresses ................................. 9 9 Authors' Addresses ................................. 9
10 Normative References ............................... 10 10 Normative References ............................... 10
11 Informative References ............................. 10 11 Informative References ............................. 10
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3. use the topology identified by the Join Attribute encoding in 3. use the topology identified by the Join Attribute encoding in
the received PIM packets. the received PIM packets.
The details of the first two methods are implementation specific and The details of the first two methods are implementation specific and
are not discussed in this document. The specification to support the are not discussed in this document. The specification to support the
third method is included in this document. third method is included in this document.
3.2. PIM MT-ID 3.2. PIM MT-ID
For each PIM RPF topology created, a unique numerical ID is assigned. For each PIM RPF topology created, a unique numerical ID is assigned
This ID is called PIM MT-ID. PIM MT-ID has the following property, per PIM domain. This ID is called PIM MT-ID. PIM MT-ID has the
following property,
- this value is not required to be the same as the MT-ID used by - this value is not required to be the same as the MT-ID used by
the unicast routing protocols that contribute routes to the the unicast routing protocols that contribute routes to the
topology. Although in practice, when only one unicast routing topology. In practice, when only one unicast routing protocol
protocol (such as OSPF or IS-IS) is used, PIM MT-ID is typically (such as OSPF or IS-IS) is used, PIM MT-ID is recommended to be
assigned the same value as the IGP topology identifier. assigned using the same value as the IGP topology identifier.
This is for the purpose of reducing management overhead and
simplifying troubleshooting.
- this value must be unique and consistent within the network - this value must be unique and consistent within the network
domain for the same topology domain for the same topology
- 0 is reserved as the default, and MUST NOT be included in the - 0 is reserved as the default, and MUST NOT be included in the
join attribute encoding. join attribute encoding.
- how to assign a PIM MT-ID to a topology is decided by the network - how to assign a PIM MT-ID to a topology is decided by the network
administrator and is outside the scope of this document administrator and is outside the scope of this document
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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 any of the
routers on the LAN does not include "PIM Join Attribute" or "PIM routers on the LAN does not include "PIM Join Attribute" or "PIM
MT-ID" option 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.
4.2.2. 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,
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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" or "PIM MT-ID" option in its that has included "PIM Join Attribute" or "PIM MT-ID" option in its
Hello packets, the encoding may still be considered valid by an Hello packets, the encoding may still be considered valid by an
implementation. implementation.
4.2.4. Conflict Resolution 4.2.4. Conflict Resolution
Depending on whether a PIM router is an upstream or a downstream It is important to note that the definition of "PIM MT-ID conflict"
router, the action it takes to resolve conflicting PIM MT-ID varies depending on whether it is on an upstream or a downstream
attributes differs. The detail is described below. router.
4.2.4.1. Upstream Routers
If an upstream router has a local configuration that specifies a On an upstream router, a conflict occurs when the router doesn't have
local topology selection policy and it has received different PIM
MT-ID from Join packets sent by its downstream routers or Assert
packets from another forwarding router on the LAN. In another word,
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 does not apply the conflict resolution procedures.
A conflict occurs when a router doesn't have local topology selection On the other hand,when a downstream router sees a different PIM MT-ID
policy and it has received different PIM MT-ID from Join packets sent attribute from other routers on the LAN it applies rules to resolve
by its downstream routers or Assert packets from another forwarding the conflicts regardless of whether the router has local topology
router on the LAN. selection policy or not.
It MUST be noted that the MT-ID value being considered for comparison 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 does not include the four reserved bits. That is, only the lower
order 12 bits are used in resolving conflicting attributes. order 12 bits are used in resolving conflicting attributes.
4.2.4.1. Conflict Resolution Rules For Upstream Routers
- 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.
In order to minimize the chances of potential transient
forwarding loops, an upstream router MAY choose to ignore the
incoming PIM Join/Prune packets all together if it sees a
conflict in PIM MT-ID attributes.
- 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.
4.2.4.2. Downstream Routers 4.2.4.2. Conflict Resolution Rules For Downstream Routers
A conflict is detected by a downstream router when it sees a
different PIM MT-ID attribute from other routers on the LAN,
regardless of whether the router has local topology selection policy
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
seen. seen.
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. Packet Format 5. Packet Format
5.1. PIM MT-ID Hello Option 5.1. PIM MT-ID Hello Option
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OptionType | OptionLength | | OptionType | OptionLength |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OptionValue | | OptionValue |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- OptionType: to be assigned by IANA. - OptionType: 30.
- OptionLength: 8 - OptionLength: 8.
- OptionValue: There is none specified at this moment. - OptionValue: There is none specified at this moment.
5.2. PIM MT-ID Join Attribute TLV Format 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. Range 2048 to 4095 are for - Value: PIM MT-ID, 1 to 4095. Range 2048 to 4095 are for
experimental and proprietary use. experimental and proprietary use.
6. IANA Considerations 6. IANA Considerations
A new PIM Hello Option type needs to be assigned. A new PIM Hello Option type, 30, has been assigned for PIM MT-ID
Hello Option. The detail is in [HELLO].
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, Les Ginsberg and Dimitri Papadimitriou for Farinacci, Colby Barth, Les Ginsberg, Dimitri Papadimitriou and
their input. Thomas Morin 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
Heidi Ou Heidi Ou
Cisco Systems, Inc Cisco Systems, Inc
170 West Tasman Drive 170 West Tasman Drive
San Jose, CA 95134 San Jose, CA 95134
E-mail: hou@cisco.com E-mail: hou@cisco.com
10. Normative References 10. Normative References
[RFC2119] S. Bradner, "Key words for use in RFCs to Indicate [RFC2119] S. Bradner, "Key words for use in RFCs to Indicate
skipping to change at page 10, line 29 skipping to change at page 10, line 35
[RFC4915] P. Psenak, S. Mirtorabi, A. Roy, L. Nguyen, P. Pillay- [RFC4915] P. Psenak, S. Mirtorabi, A. Roy, L. Nguyen, P. Pillay-
Esnault, "Multi-Topology (MT) Routing in OSPF", RFC 4915, June 2007. Esnault, "Multi-Topology (MT) Routing in OSPF", RFC 4915, June 2007.
[RFC5120] T. Przygienda, N. Shen, N. Sheth, "M-ISIS: Multi Topology [RFC5120] T. Przygienda, N. Shen, N. Sheth, "M-ISIS: Multi Topology
(MT) Routing in Intermediate System to Intermediate Systems (IS- (MT) Routing in Intermediate System to Intermediate Systems (IS-
ISs)", RFC 5120, February 2008. ISs)", RFC 5120, February 2008.
[RFC5496] I. Wijnands, A. Boers, E. Rosen, "The Reverse Path [RFC5496] I. Wijnands, A. Boers, E. Rosen, "The Reverse Path
Forwarding (RPF) Vector TLV", RFC 5496, March 2009. Forwarding (RPF) Vector TLV", RFC 5496, March 2009.
[HELLO] IANA, "PIM-Hello Options",
http://www.iana.org/assignments/pim-parameters/pim-
parameters.xhtml#pim-parameters-1
[ID.ietf-l3vpn-2547bis-mcast] E. Rosen,R Aggarwal, "Multicast in [ID.ietf-l3vpn-2547bis-mcast] E. Rosen,R Aggarwal, "Multicast in
MPLS/BGP IP VPNs", draft-ietf-l3vpn-2547bis-mcast-08, March 2009 MPLS/BGP IP VPNs", draft-ietf-l3vpn-2547bis-mcast-10, January 2010
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