draft-ietf-pim-drlb-14.txt   draft-ietf-pim-drlb-15.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: June 13, 2020 S. Vallepalli Expires: July 6, 2020 S. Vallepalli
M. Mishra M. Mishra
S. Venaas S. Venaas
Cisco Systems, Inc. Cisco Systems, Inc.
A. Green A. Green
British Telecom British Telecom
December 11, 2019 January 3, 2020
PIM Designated Router Load Balancing PIM Designated Router Load Balancing
draft-ietf-pim-drlb-14 draft-ietf-pim-drlb-15
Abstract Abstract
On a multi-access network, one of the PIM-SM (PIM Sparse Mode) On a multi-access network, one of the PIM-SM (PIM Sparse Mode)
routers is elected as a Designated Router. One of the routers is elected as a Designated Router. One of the
responsibilities of the Designated Router is to track local multicast responsibilities of the Designated Router is to track local multicast
listeners and forward data to these listeners if the group is listeners and forward data to these listeners if the group is
operating in PIM-SM. This document specifies a modification to the operating in PIM-SM. This document specifies a modification to the
PIM-SM protocol that allows more than one of the PIM-SM routers to PIM-SM protocol that allows more than one of the PIM-SM routers to
take on this responsibility so that the forwarding load can be take on this responsibility so that the forwarding load can be
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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 June 13, 2020. This Internet-Draft will expire on July 6, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2020 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
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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
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4. Functional Overview . . . . . . . . . . . . . . . . . . . . . 5 4. Functional Overview . . . . . . . . . . . . . . . . . . . . . 5
4.1. GDR Candidates . . . . . . . . . . . . . . . . . . . . . 6 4.1. GDR Candidates . . . . . . . . . . . . . . . . . . . . . 6
5. Protocol Specification . . . . . . . . . . . . . . . . . . . 7 5. Protocol Specification . . . . . . . . . . . . . . . . . . . 7
5.1. Hash Mask and Hash Algorithm . . . . . . . . . . . . . . 7 5.1. Hash Mask and Hash Algorithm . . . . . . . . . . . . . . 7
5.2. Modulo Hash Algorithm . . . . . . . . . . . . . . . . . . 8 5.2. Modulo Hash Algorithm . . . . . . . . . . . . . . . . . . 8
5.2.1. Modulo Hash Algorithm Examples . . . . . . . . . . . 9 5.2.1. Modulo Hash Algorithm Examples . . . . . . . . . . . 9
5.2.2. Limitations . . . . . . . . . . . . . . . . . . . . . 10 5.2.2. Limitations . . . . . . . . . . . . . . . . . . . . . 10
5.3. PIM Hello Options . . . . . . . . . . . . . . . . . . . . 11 5.3. PIM Hello Options . . . . . . . . . . . . . . . . . . . . 11
5.3.1. PIM DR Load Balancing Capability (DRLB-Cap) Hello 5.3.1. PIM DR Load Balancing Capability (DRLB-Cap) Hello
Option . . . . . . . . . . . . . . . . . . . . . . . 11 Option . . . . . . . . . . . . . . . . . . . . . . . 11
5.3.2. PIM DR Load Balancing List (DRLB-List) Hello Option . 11 5.3.2. PIM DR Load Balancing List (DRLB-List) Hello Option . 12
5.4. PIM DR Operation . . . . . . . . . . . . . . . . . . . . 13 5.4. PIM DR Operation . . . . . . . . . . . . . . . . . . . . 13
5.5. PIM GDR Candidate Operation . . . . . . . . . . . . . . . 14 5.5. PIM GDR Candidate Operation . . . . . . . . . . . . . . . 14
5.6. DRLB-List Hello Option Processing . . . . . . . . . . . . 14 5.6. DRLB-List Hello Option Processing . . . . . . . . . . . . 14
5.7. PIM Assert Modification . . . . . . . . . . . . . . . . . 15 5.7. PIM Assert Modification . . . . . . . . . . . . . . . . . 15
5.8. Backward Compatibility . . . . . . . . . . . . . . . . . 16 5.8. Backward Compatibility . . . . . . . . . . . . . . . . . 16
6. Operational Considerations . . . . . . . . . . . . . . . . . 16 6. Operational Considerations . . . . . . . . . . . . . . . . . 16
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
7.1. Initial registry . . . . . . . . . . . . . . . . . . . . 17 7.1. Initial registry . . . . . . . . . . . . . . . . . . . . 17
7.2. Assignment of new Hash Algorithms . . . . . . . . . . . . 17 7.2. Assignment of new Hash Algorithms . . . . . . . . . . . . 17
8. Security Considerations . . . . . . . . . . . . . . . . . . . 17 8. Security Considerations . . . . . . . . . . . . . . . . . . . 17
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5.2.2. Limitations 5.2.2. Limitations
The Modulo Hash Algorithm has poor failover characteristics when a The Modulo Hash Algorithm has poor failover characteristics when a
shared LAN has more than two GDRs. In the case of more than two GDRs shared LAN has more than two GDRs. In the case of more than two GDRs
on a LAN, when one GDR fails, all of the groups may be reassigned to on a LAN, when one GDR fails, all of the groups may be reassigned to
a different GDR, even if they were not assigned to the failed GDR. a different GDR, even if they were not assigned to the failed GDR.
However, many deployments use only two routers on a shared LAN for However, many deployments use only two routers on a shared LAN for
redundancy purposes. Future work may define new Hash Algorithms redundancy purposes. Future work may define new Hash Algorithms
where only groups assigned to the failed GDR get reassigned. where only groups assigned to the failed GDR get reassigned.
The Modulo Hash Algorithm will use at most 32 consecutive bits of the
input addresses for its computation. Exactly which bits are used of
the source, group or RP addresses, depend on the respective masks.
This limitation may be an issue for IPv6 deployments, since not all
bits of the IPv6 addresses are considered. If this causes
operational issues, a new hash algorithm would need to be defined.
5.3. PIM Hello Options 5.3. PIM Hello Options
PIM routers include a new option, called "Load Balancing Capability PIM routers include a new option, called "Load Balancing Capability
(DRLB-Cap)" in their PIM Hello messages. (DRLB-Cap)" in their PIM Hello messages.
Besides this DRLB-Cap Hello Option, the elected PIM DR also includes Besides this DRLB-Cap Hello Option, the elected PIM DR also includes
a new "DR Load Balancing List (DRLB-List) Hello Option". The DRLB- a new "DR Load Balancing List (DRLB-List) Hello Option". The DRLB-
List Hello Option consists of three Hash Masks as defined above and List Hello Option consists of three Hash Masks as defined above and
also a list of GDR Candidate addresses on the LAN. It is recommended also a list of GDR Candidate addresses on the LAN. It is recommended
that the GDR Candidate addresses are sorted in descending order. that the GDR Candidate addresses are sorted in descending order.
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