draft-ietf-pim-drlb-09.txt   draft-ietf-pim-drlb-10.txt 
Network Working Group Y. Cai Network Working Group Y. Cai
Internet-Draft H. Ou Internet-Draft H. Ou
Intended status: Standards Track Alibaba Group Intended status: Standards Track Alibaba Group
Expires: April 25, 2019 S. Vallepalli Expires: May 17, 2019 S. Vallepalli
M. Mishra M. Mishra
S. Venaas S. Venaas
Cisco Systems, Inc. Cisco Systems, Inc.
A. Green A. Green
British Telecom British Telecom
October 22, 2018 November 13, 2018
PIM Designated Router Load Balancing PIM Designated Router Load Balancing
draft-ietf-pim-drlb-09 draft-ietf-pim-drlb-10
Abstract Abstract
On a multi-access network, one of the PIM routers is elected as a On a multi-access network, one of the PIM routers is elected as a
Designated Router (DR). On the last hop LAN, the PIM DR is Designated Router (DR). On the last hop LAN, the PIM DR is
responsible for tracking local multicast listeners and forwarding responsible for tracking local multicast listeners and forwarding
traffic to these listeners if the group is operating in PIM-SM. This traffic to these listeners if the group is operating in PIM-SM. This
document specifies a modification to the PIM-SM protocol that allows document specifies a modification to the PIM-SM protocol that allows
more than one of these last hop routers to be selected, so that the more than one of these last hop routers to be selected, so that the
forwarding load can be distributed among these routers. forwarding load can be distributed among these routers.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 25, 2019. This Internet-Draft will expire on May 17, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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6. Protocol Specification . . . . . . . . . . . . . . . . . . . 11 6. Protocol Specification . . . . . . . . . . . . . . . . . . . 11
6.1. PIM DR Operation . . . . . . . . . . . . . . . . . . . . 11 6.1. PIM DR Operation . . . . . . . . . . . . . . . . . . . . 11
6.2. PIM GDR Candidate Operation . . . . . . . . . . . . . . . 12 6.2. PIM GDR Candidate Operation . . . . . . . . . . . . . . . 12
6.2.1. Router Receives New DRLBGDR . . . . . . . . . . . . . 13 6.2.1. Router Receives New DRLBGDR . . . . . . . . . . . . . 13
6.2.2. Router Receives Updated DRLBGDR . . . . . . . . . . . 13 6.2.2. Router Receives Updated DRLBGDR . . . . . . . . . . . 13
6.3. PIM Assert Modification . . . . . . . . . . . . . . . . . 14 6.3. PIM Assert Modification . . . . . . . . . . . . . . . . . 14
7. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 15 7. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 15
8. Manageability Considerations . . . . . . . . . . . . . . . . 16 8. Manageability Considerations . . . . . . . . . . . . . . . . 16
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
9.1. Initial registry . . . . . . . . . . . . . . . . . . . . 16 9.1. Initial registry . . . . . . . . . . . . . . . . . . . . 16
9.2. Assignment of new message types . . . . . . . . . . . . . 16 9.2. Assignment of new hash algorithms . . . . . . . . . . . . 16
10. Security Considerations . . . . . . . . . . . . . . . . . . . 16 10. Security Considerations . . . . . . . . . . . . . . . . . . . 16
11. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 17 11. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 17
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 17 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
12.1. Normative References . . . . . . . . . . . . . . . . . . 17 12.1. Normative References . . . . . . . . . . . . . . . . . . 17
12.2. Informative References . . . . . . . . . . . . . . . . . 17 12.2. Informative References . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction 1. Introduction
On a multi-access LAN such as an Ethernet, one of the PIM routers is On a multi-access LAN such as an Ethernet, one of the PIM routers is
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o If the group is in ASM mode and the RP Hash Mask announced by the o If the group is in ASM mode and the RP Hash Mask announced by the
PIM DR is 0, obtain the value of hashvalue_Group [Section 4.3 ] to PIM DR is 0, obtain the value of hashvalue_Group [Section 4.3 ] to
determine GDR. determine GDR.
o If the group is in SSM mode, use hashvalue_SG [Section 4.3] to o If the group is in SSM mode, use hashvalue_SG [Section 4.3] to
determine GDR. determine GDR.
A simple Modulo hash algorithm is defined in this document. However, A simple Modulo hash algorithm is defined in this document. However,
to allow another hash algorithms to be used, a 1-octet "Hash to allow another hash algorithms to be used, a 1-octet "Hash
Algorithm Type" field is included in DRLBC Hello Option to specify Algorithm" field is included in DRLBC Hello Option to specify the
the hash algorithm used by a last hop router. hash algorithm used by a last hop router.
If different hash algorithm types are advertised among last hop If different hash algorithms are advertised among last hop routers,
routers, only last hop routers running the same hash algorithm as the only last hop routers running the same hash algorithm as the DR (and
DR (and having the same DR priority as the DR) are eligible for GDR having the same DR priority as the DR) are eligible for GDR election.
election.
4.3. Modulo Hash Algorithm 4.3. Modulo Hash Algorithm
The Modulo hash algorithm is discussed here with a detailed The Modulo hash algorithm is discussed here with a detailed
description on hashvalue_RP. The same algorithm is described in description on hashvalue_RP. The same algorithm is described in
brief for hashvalue_Group using the group address instead of the RP brief for hashvalue_Group using the group address instead of the RP
address for an ASM group with zero RP_hashmask, and also with address for an ASM group with zero RP_hashmask, and also with
hashvalue_SG for a the source address of an (S,G), instead of the RP hashvalue_SG for a the source address of an (S,G), instead of the RP
address, address,
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5. Hello Option Formats 5. Hello Option Formats
5.1. PIM DR Load Balancing Capability (DRLBC) Hello Option 5.1. PIM DR Load Balancing Capability (DRLBC) 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = TBD | Length = 4 | | Type = TBD | Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Hash Type | | Reserved |Hash Algorithm |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Capability Hello Option Figure 3: Capability Hello Option
Type: TBD Type: TBD
Length: 4 Length: 4
Hash Algorithm Type: 0 for Modulo hash algorithm Hash Algorithm: 0 for Modulo
This DRLBC Hello Option MUST be advertised by last hop routers on This DRLBC Hello Option MUST be advertised by last hop routers on
interfaces with this specification enabled. interfaces with this specification enabled.
5.2. PIM DR Load Balancing GDR (DRLBGDR) Hello Option 5.2. PIM DR Load Balancing GDR (DRLBGDR) 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = TBD | Length | | Type = TBD | Length |
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configuration, followed by a sorted list of GDR Candidate Addresses, configuration, followed by a sorted list of GDR Candidate Addresses,
from the highest value to the lowest value. Moreover, same as non-DR from the highest value to the lowest value. Moreover, same as non-DR
routers, the DR also advertises DRLBC Hello Option to indicate its routers, the DR also advertises DRLBC Hello Option to indicate its
capability of supporting this specification and the type of its GDR capability of supporting this specification and the type of its GDR
election hash algorithm. election hash algorithm.
If a PIM DR receives a PIM Hello with the DRLBGDR Option, the PIM DR If a PIM DR receives a PIM Hello with the DRLBGDR Option, the PIM DR
SHOULD ignore the TLV. SHOULD ignore the TLV.
If a PIM DR receives a neighbor DRLBC Hello Option, which contains If a PIM DR receives a neighbor DRLBC Hello Option, which contains
the same hash algorithm type as the DR, and the neighbor has the same the same hash algorithm as the DR, and the neighbor has the same DR
DR priority as the DR, PIM DR SHOULD consider the neighbor as a GDR priority as the DR, PIM DR SHOULD consider the neighbor as a GDR
Candidate and insert the GDR Candidate's Address into the sorted list Candidate and insert the GDR Candidate's Address into the sorted list
of the DRLBGDR Option. However, the DR MAY have policies limiting of the DRLBGDR Option. However, the DR MAY have policies limiting
which GDR Candidates, or the number of GDR Candidates to include. which GDR Candidates, or the number of GDR Candidates to include.
6.2. PIM GDR Candidate Operation 6.2. PIM GDR Candidate Operation
When an IGMP/MLD report is received, without this specification, only When an IGMP/MLD report is received, without this specification, only
the PIM DR will handle the join and potentially run into the issues the PIM DR will handle the join and potentially run into the issues
described earlier. Using this specification, a hash algorithm is described earlier. Using this specification, a hash algorithm is
used by the GDR Candidates to determine which router is going to be used by the GDR Candidates to determine which router is going to be
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o If a router which does not support this specification becomes a o If a router which does not support this specification becomes a
non-DR on link, then it acts as non-DR defined in [RFC7761], and non-DR on link, then it acts as non-DR defined in [RFC7761], and
it will not take part in any load-balancing. it will not take part in any load-balancing.
8. Manageability Considerations 8. Manageability Considerations
Only the routers announcing the same Hash Algorithm as the DR would Only the routers announcing the same Hash Algorithm as the DR would
be considered as GDR candidates. Network administrators need to make be considered as GDR candidates. Network administrators need to make
sure that the desired set of routers announce the same algorithm. sure that the desired set of routers announce the same algorithm.
Migration between different algorithm types is not considered in this Migration between different algorithms is not considered in this
document. document.
9. IANA Considerations 9. IANA Considerations
IANA has temporarily assigned type 34 for the PIM DR Load Balancing IANA has temporarily assigned type 34 for the PIM DR Load Balancing
Capability (DRLBC) Hello Option, and type 35 for the PIM DR Load Capability (DRLBC) Hello Option, and type 35 for the PIM DR Load
Balancing GDR (DRLBGDR) Hello Option. IANA is requested to make Balancing GDR (DRLBGDR) Hello Option in the PIM-Hello Options
these assignments permanent when this document is published as an registry. IANA is requested to make these assignments permanent when
RFC. The string TBD should be replaced by the assigned values this document is published as an RFC. The string TBD should be
accordingly. This document requests IANA to create a DRLB hash type replaced by the assigned values accordingly.
registry. This should be placed in the "Protocol Independent
Multicast (PIM)" branch of the tree. This document requests IANA to create a registry called "Designated
Router Load Balancing Hash Algorithms" in the "Protocol Independent
Multicast (PIM)" branch of the registry tree. The registry lists
hash algorithms for use by PIM Designated Router Load Balancing.
9.1. Initial registry 9.1. Initial registry
The initial content of the registry should be as follows. The initial content of the registry should be as follows.
Type Name Reference Type Name Reference
------ ---------------------------------------- -------------------- ------ ---------------------------------------- --------------------
0 Hash algorithm modulo This document 0 Modulo This document
1-255 Unassigned 1-255 Unassigned
9.2. Assignment of new message types 9.2. Assignment of new hash algorithms
Assignment of new message types is done according to the "IETF Assignment of new hash algorithms is done according to the "IETF
Review" model, see [RFC5226]. Review" model, see [RFC5226].
10. Security Considerations 10. Security Considerations
Security of the new DR Load Balancing PIM Hello Options is only Security of the new DR Load Balancing PIM Hello Options is only
guaranteed by the security of PIM Hello messages, so the security guaranteed by the security of PIM Hello messages, so the security
considerations for PIM Hello messages as described in PIM-SM considerations for PIM Hello messages as described in PIM-SM
[RFC7761] apply here. [RFC7761] apply here.
11. Acknowledgement 11. Acknowledgement
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