draft-ietf-rtgwg-mofrr-05.txt   draft-ietf-rtgwg-mofrr-06.txt 
Network Working Group A. Karan Network Working Group A. Karan
Internet-Draft C. Filsfils Internet-Draft C. Filsfils
Intended status: Informational IJ. Wijnands, Ed. Intended status: Informational IJ. Wijnands, Ed.
Expires: August 7, 2015 Cisco Systems, Inc. Expires: August 8, 2015 Cisco Systems, Inc.
B. Decraene B. Decraene
Orange Orange
February 3, 2015 February 4, 2015
Multicast only Fast Re-Route Multicast only Fast Re-Route
draft-ietf-rtgwg-mofrr-05 draft-ietf-rtgwg-mofrr-06
Abstract Abstract
As IPTV deployments grow in number and size, service providers are As IPTV deployments grow in number and size, service providers are
looking for solutions that minimize the service disruption due to looking for solutions that minimize the service disruption due to
faults in the IP network carrying the packets for these services. faults in the IP network carrying the packets for these services.
This document describes a mechanism for minimizing packet loss in a This document describes a mechanism for minimizing packet loss in a
network when node or link failures occur. Multicast only Fast Re- network when node or link failures occur. Multicast only Fast Re-
Route (MoFRR) works by making simple enhancements to multicast Route (MoFRR) works by making simple enhancements to multicast
routing protocols such as PIM and mLDP. routing protocols such as PIM and mLDP.
Status of this Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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 http://datatracker.ietf.org/drafts/current/. Drafts is at http://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 August 7, 2015. This Internet-Draft will expire on August 8, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions used in this document . . . . . . . . . . . . 3 1.1. Conventions used in this document . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Basic Overview . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Basic Overview . . . . . . . . . . . . . . . . . . . . . . . 4
3. Determination of the secondary UMH . . . . . . . . . . . . . . 5 3. Determination of the secondary UMH . . . . . . . . . . . . . 4
3.1. ECMP-mode MoFRR . . . . . . . . . . . . . . . . . . . . . 5 3.1. ECMP-mode MoFRR . . . . . . . . . . . . . . . . . . . . . 4
3.2. Non-ECMP-mode MoFRR . . . . . . . . . . . . . . . . . . . 5 3.2. Non-ECMP-mode MoFRR . . . . . . . . . . . . . . . . . . . 5
4. Upstream Multicast Hop Selection . . . . . . . . . . . . . . . 6 4. Upstream Multicast Hop Selection . . . . . . . . . . . . . . 5
4.1. PIM . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4.1. PIM . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.2. mLDP . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4.2. mLDP . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5. Detecting Failures . . . . . . . . . . . . . . . . . . . . . . 6 5. Detecting Failures . . . . . . . . . . . . . . . . . . . . . 6
6. MoFRR applicability . . . . . . . . . . . . . . . . . . . . . 7 6. MoFRR applicability . . . . . . . . . . . . . . . . . . . . . 7
6.1. Dual-Plane Topology . . . . . . . . . . . . . . . . . . . 7 6.1. Dual-Plane Topology . . . . . . . . . . . . . . . . . . . 7
6.2. Capacity Planning for MoFRR . . . . . . . . . . . . . . . 10 6.2. Capacity Planning for MoFRR . . . . . . . . . . . . . . . 10
6.3. PE nodes . . . . . . . . . . . . . . . . . . . . . . . . . 11 6.3. PE nodes . . . . . . . . . . . . . . . . . . . . . . . . 11
6.4. Other Applications . . . . . . . . . . . . . . . . . . . . 11 6.4. Other Applications . . . . . . . . . . . . . . . . . . . 11
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
8. Security Considerations . . . . . . . . . . . . . . . . . . . 12 8. Security Considerations . . . . . . . . . . . . . . . . . . . 12
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12
10. Contributor Addresses . . . . . . . . . . . . . . . . . . . . 12 10. Contributor Addresses . . . . . . . . . . . . . . . . . . . . 12
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
11.1. Normative References . . . . . . . . . . . . . . . . . . . 13 11.1. Normative References . . . . . . . . . . . . . . . . . . 13
11.2. Informative References . . . . . . . . . . . . . . . . . . 13 11.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction 1. Introduction
Different solutions have been developed and deployed to improve Different solutions have been developed and deployed to improve
service guarantees, both for multicast video traffic and Video on service guarantees, both for multicast video traffic and Video on
Demand traffic. Most of these solutions are geared towards finding Demand traffic. Most of these solutions are geared towards finding
an alternate path around one or more failed network elements (link, an alternate path around one or more failed network elements (link,
node, path failures). node, path failures).
This document describes a mechanism for minimizing packet loss in a This document describes a mechanism for minimizing packet loss in a
skipping to change at page 4, line 40 skipping to change at page 4, line 22
MVPN: Multicast Virtual Private Networks. MVPN: Multicast Virtual Private Networks.
2. Basic Overview 2. Basic Overview
The basic idea of MoFRR is for a Merge Point router to join a The basic idea of MoFRR is for a Merge Point router to join a
multicast tree via two divergent upstream paths in order to get multicast tree via two divergent upstream paths in order to get
maximum redundancy. The determination of this alternate upstream is maximum redundancy. The determination of this alternate upstream is
defined in Section 3. defined in Section 3.
In order maximize robustness against any failure, the two paths In order to maximize robustness against any failure, the two paths
should be as diverse as possible. Ideally, they should not merge should be as diverse as possible. Ideally, they should not merge
upstream. Sometimes the topology guarantees maximal redundancy, upstream. Sometimes the topology guarantees maximal redundancy,
other times additional configuration or techniques are needed to other times additional configuration or techniques are needed to
enforce it. See Section 6 for more discussion on the applicability enforce it. See Section 6 for more discussion on the applicability
of MoFRR depending on the network topology. of MoFRR depending on the network topology.
A Merge Point router should only accept and forward on one of the A Merge Point router should only accept and forward on one of the
upstream paths at a time in order to avoid duplicate packet upstream paths at a time in order to avoid duplicate packet
forwarding. The selection of the primary and secondary UMH is done forwarding. The selection of the primary and secondary UMH is done
by the MoFRR logic and normally based on unicast routing to find loop by the MoFRR logic and normally based on unicast routing to find loop
skipping to change at page 5, line 27 skipping to change at page 5, line 8
If the IGP installs two ECMP paths to the source, then as per If the IGP installs two ECMP paths to the source, then as per
[RFC5286] the LFA is a primary Next-hop. If the Multicast tree is [RFC5286] the LFA is a primary Next-hop. If the Multicast tree is
enabled for ECMP-Mode MoFRR, the router installs them as primary and enabled for ECMP-Mode MoFRR, the router installs them as primary and
secondary UMH. Before the failure, only packets received from the secondary UMH. Before the failure, only packets received from the
primary UMH path are processed while packets received from the primary UMH path are processed while packets received from the
secondary UMH are dropped. secondary UMH are dropped.
The selected primary UMH SHOULD be the same as if the MoFRR extension The selected primary UMH SHOULD be the same as if the MoFRR extension
was not enabled. was not enabled.
If more than two ECMP paths exist, one is selected as primary and and If more than two ECMP paths exist, one is selected as primary and
other as secondary UMH. The selection of the primary and secondary another as secondary UMH. The selection of the primary and secondary
is a local decision. Information from the IGP link-state topology is a local decision. Information from the IGP link-state topology
could be leveraged to optimize this selection such that the primary could be leveraged to optimize this selection such that the primary
and secondary path are maximal divergent and don't lead to the same and secondary path are maximal divergent and don't lead to the same
upstream node. Note that MoFRR does not restrict the number of UMH upstream node. Note that MoFRR does not restrict the number of UMH
paths that are joined. Implementations may use as many paths as are paths that are joined. Implementations may use as many paths as are
configured. configured.
3.2. Non-ECMP-mode MoFRR 3.2. Non-ECMP-mode MoFRR
A router X configured for non-ECMP-mode MoFRR for a Multicast tree A router X configured for non-ECMP-mode MoFRR for a Multicast tree
joins a primary path to its primary UMH R(X) and a secondary path to joins a primary path to its primary UMH and a secondary path to its
LFA UMH N. In order to prevent control-plane loops a router MUST stop LFA UMH. In order to prevent control-plane loops a router MUST stop
joining the secondary UMH if this UMH is the only member in the OIF joining the secondary UMH if this UMH is the only member in the OIF
list. list.
To illustrate the reason for this rule, let's consider the example in To illustrate the reason for this rule, let's consider the example in
FIG3. If PE1 and PE2 have received an IGMP request for a Multicast FIG3. If PE1 and PE2 have received an IGMP request for a Multicast
tree, they will both join the primary path on their plane and a tree, they will both join the primary path on their plane and a
secondary path to the neighbor PE. If their receivers would leave at secondary path to the neighbor PE. If their receivers would leave at
the same time, it could be possible for the Multicast tree on PE1 and the same time, it could be possible for the Multicast tree on PE1 and
PE2 to never get deleted as each PE refresh each other via the PE2 to never get deleted as each PE refresh each other via the
secondary path joins (remember that a secondary path join is not secondary path joins (remember that a secondary path join is not
skipping to change at page 8, line 40 skipping to change at page 8, line 40
PE1 PE2 PE1 PE2
P = Primary path P = Primary path
S = Secondary path S = Secondary path
FIG1. Two-Plane Network Design FIG1. Two-Plane Network Design
The topology has two planes, a primary plane and a secondary plane The topology has two planes, a primary plane and a secondary plane
that are fully disjoint from each other all the way into the POPs. that are fully disjoint from each other all the way into the POPs.
This two plane design is common in service provider networks as it This two plane design is common in service provider networks as it
eliminates single point of failures in their core network. The links eliminates single point of failures in their core network. The links
marked PJ indicate the normal path of how the PIM joins flow from the marked P indicate the normal (Primary) path of how the PIM joins flow
POPs towards the source of the network. Multicast streams, from the POPs towards the source of the network. Multicast streams,
especially for the densely watched channels, typically flow along especially for the densely watched channels, typically flow along
both the planes in the network anyway. both the planes in the network anyway.
The only change MoFRR adds to this is on the links marked S where the The only change MoFRR adds to this is on the links marked S where the
PE routers join a secondary path to their secondary ECMP UMH. As a PE routers join a secondary path to their secondary ECMP UMH. As a
result of this, each PE router receives two copies of the same result of this, each PE router receives two copies of the same
stream, one from the primary plane and the other from the secondary stream, one from the primary plane and the other from the secondary
plane. As a result of normal UMH behavior, the multicast stream plane. As a result of normal UMH behavior, the multicast stream
received over the primary path is accepted and forwarded to the received over the primary path is accepted and forwarded to the
downstream receivers. The copy of the stream received from the downstream receivers. The copy of the stream received from the
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