Internet DRAFT - draft-zzhang-mpls-rmr-multicast
draft-zzhang-mpls-rmr-multicast
MPLS Z. Zhang
Internet-Draft Juniper Networks
Intended status: Informational S. Esale
Expires: November 8, 2019 Juniper Networks, Inc.
May 7, 2019
Resilient MPLS Rings and Multicast
draft-zzhang-mpls-rmr-multicast-03
Abstract
With Resilient MPLS Rings (RMR), although all existing multicast
procedures and solutions can work as is, there are optimizations that
could be done for RSVP-TE P2MP tunnel signaling and Fast-ReRouting
for both mLDP and RSVP-TE P2MP tunnels. This document describes RMR
multicast on a high level, with detailed protocol procedure for RSVP-
TE P2MP optimizations specified in a separate document. This
document also discusses end to end multicast when there are RMRs.
Status of This Memo
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This Internet-Draft will expire on November 8, 2019.
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include Simplified BSD License text as described in Section 4.e of
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. P2MP/MP2MP Tunnels on a Ring . . . . . . . . . . . . . . . . 3
2.1. Tunnel Protection and FRR . . . . . . . . . . . . . . . . 3
3. End to End Tunnels with Rings . . . . . . . . . . . . . . . . 4
4. End to End Native Multicast with Rings . . . . . . . . . . . 4
4.1. Native Multicast in the Global Routing Table . . . . . . 4
4.2. mLDP Inband Signaling . . . . . . . . . . . . . . . . . . 4
4.3. Overlay Multicast Services . . . . . . . . . . . . . . . 4
4.3.1. Tunnel Segmentation . . . . . . . . . . . . . . . . . 5
5. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
9.1. Normative References . . . . . . . . . . . . . . . . . . 6
9.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
This document discusses how multicast works with Resilient MPLS Rings
[I-D.ietf-mpls-rmr]. It is expected that readers are familiar with
the concept and terms in [I-D.ietf-mpls-rmr].
All existing multicast procedures and solutions can work as is. This
include both mpls multicast tunnels and end-to-end multicast that
makes use of multicast tunnels. Ring topology is just a special case
of general topologies so all existing RSVP-TE P2MP [RFC4875] and mLDP
[RFC6388] tunnels can be set up using existing protocols and
procedures. An Ingress Replication (IR) tunnel [RFC7988] consists a
bunch of P2P LSPs, and it does not matter whether a component LSP is
a plain old LSP or a Ring LSP.
On the other hand, there are optimizations that could be done for
RSVP-TE P2MP tunnel signaling and Fast-ReRouting (FRR) for both mLDP
and RSVP-TE P2MP tunnels. This document describes that on a high
level, and discusses end to end multicast when there are RMRs even
though RMR could be transparent to multicast.
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2. P2MP/MP2MP Tunnels on a Ring
Because mLDP label mapping messages are merged as they propagate from
the leaves towards the root, ring topology does not lead to any
further optimization in tunnel signaling.
However RSVP-TE P2MP tunnel signaling and procedures can be greatly
optimized, as specified in [I-D.zzhang-teas-rmr-rsvp-p2mp].
2.1. Tunnel Protection and FRR
Each node on a ring signals two counter-rotating MP2P Ring LSPs to
itself. As these LSPs are self-signaled after the discovery of the
ring, they can be used to protect P2MP LSPs on ring. So neither mLDP
nor RSVP-TE has to setup a separate P2P bypass LSPs for link and node
protection. For instance, consider a ring with 8 nodes:
Root
R0 . . . R1
. .
R7 R2 Leaf
| . . |
Anti- | . RingID=17 . |
Clockwise v . . v Clockwise
Leaf R6 R3
. .
R5 . . . R4 Leaf
Figure 1: Ring with 8 nodes
Further, suppose a P2MP LSP is signaled with R0 as a root and R2, R4
and R6 as leafs. The P2MP LSP is formed as follows:
R0
. .
. .
. .
R6 R2
.
.
R4
Figure 2: P2MP LSP
In the event of a link failure between R2 and R3, R2 the Point of
Local Repair (PLR) tunnels P2MP LSP traffic on a anti-clockwise ring
LSP to R3 the Merge Point (MP). Once the traffic is out of the ring
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LSP on R3, it uses the regular P2MP LSP to reach R4. Similarly in
the event of a node failure R3, R2 the PLR tunnels P2MP LSP traffic
to R4 (the MP), which is also the leaf. Thus, the P2MP LSP uses the
existing RSVP-TE ring LSPs for link and node protection.
3. End to End Tunnels with Rings
Consider a provider network that consists of one or more rings,
optionally with a general topology connecting the rings. Multicast
VPN [RFC6514], Ethernet VPN [RFC7432], VPLS [RFC4761] [RFC4762], or
Global Table Multicast (GTM) via MVPN [RFC7716] overlay services are
provided where end-to-end multipoint tunnels are needed across the
entire network.
If the end to end tunnels are established by RSVP-TE P2MP, there is
not much optimization that can be done for RMR, unless overlay-
assisted tunnel segmentation is used. That is described in
Section 4.3.1.
If the end to end tunnels are established by mLDP and RSVP-TE
signaling is desired on part of the network, mLDP Over Targeted
Sessions [RFC7060] can be used (without the help from the overlay
service) to stack part of an mLDP tunnel over a RSVP-TE P2MP tunnel.
If the RSVP-TE P2MP tunnel is over a ring, then the optimization
described earlier can be used.
4. End to End Native Multicast with Rings
Consider a network that consists of some rings. In this network,
end-to-end native multicast can take various forms described below.
4.1. Native Multicast in the Global Routing Table
This is typically signaled by PIM [RFC7761] end to end. This works
for any topology and RMR does not make any difference.
4.2. mLDP Inband Signaling
This is specified in [RFC6826] [RFC7246] [RFC7438]. When part of a
native (s,g) or (*,g) multicast tree needs to go over an mLDP domain,
an mLDP tunnel is created for each multicast tree for the domain.
RMR does not make any differences here.
4.3. Overlay Multicast Services
Overlay multicast services provided by MVPN/GTM/EVPN/VPLS use overlay
multicast signaling to signal customer multicast state and tunnel
binding. PE-PE multipoint underlay tunnels are used to distribute
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multicast packets among PEs. Any kind of tunnel can be used, whether
the provider network has rings or not, with or without the RMR
related optimizations (Section 3).
4.3.1. Tunnel Segmentation
The MVPN/GTM/EVPN/VPLS PEs could span across ASes or areas. When the
PE-PE multipoint tunnels cannot be signaled across AS/area
boundaries, segmentation procedures can be used, as specified in
[RFC6514, RFC7024] and [I-D.ietf-bess-evpn-bum-procedure-updates].
With the base MVPN/GTM/EVPN/VPLS procedures, PEs advertise I/S-PMSI
A-D routes to signal traffic to tunnel binding, and the routes carry
type and identification of multi-point tunnels used to carry
corresponding traffic. With segmentation, the ASBRs/ABRs become
segmentation points and they change the tunnel type/identification
when they re-advertise the routes to the next AS/area. With this,
each AS/area has its own tunnel of different type/identification,
stitched together by the ASBRs/ABRs.
With segmentation, different RMRs could have their own tunnels, and
RSVP-TE P2MP optimizations for RMRs could be applied. Notice that
this is different from Section 3 in that overlay signaling is
involved.
5. Summary
As described above, multicast in the presence of RMRs can work as is.
RSVP-TE P2MP tunnel signaling can be optimized (to be specified
separately). Tunnel protection/FRR can also be optimized for mLDP/
RSVP-TE P2MP tunnels.
6. Security Considerations
This is an informational document that describes how existing
multicast protocols can be used with RMR, as well as possible RMR
specific enhancements that will be specified separately. There are
no security concerns to be discussed here, as they are already
discussed in existing protocols or will be discussed in the
specification for the enhancements.
7. IANA Considerations
This document does not request any allocations from IANA. The RFC
Editor is requested to remove this section before publication.
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8. Acknowledgements
The authors sincerely thank Loa Andersson for his careful review,
comments and suggestions.
9. References
9.1. Normative References
[I-D.ietf-mpls-rmr]
Kompella, K. and L. Contreras, "Resilient MPLS Rings",
draft-ietf-mpls-rmr-09 (work in progress), January 2019.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
9.2. Informative References
[I-D.zzhang-teas-rmr-rsvp-p2mp]
Zhang, Z., Deshmukh, A., and R. Singh, "RSVP-TE P2MP
Tunnels on RMR", draft-zzhang-teas-rmr-rsvp-p2mp-02 (work
in progress), January 2019.
[RFC4761] Kompella, K., Ed. and Y. Rekhter, Ed., "Virtual Private
LAN Service (VPLS) Using BGP for Auto-Discovery and
Signaling", RFC 4761, DOI 10.17487/RFC4761, January 2007,
<https://www.rfc-editor.org/info/rfc4761>.
[RFC4762] Lasserre, M., Ed. and V. Kompella, Ed., "Virtual Private
LAN Service (VPLS) Using Label Distribution Protocol (LDP)
Signaling", RFC 4762, DOI 10.17487/RFC4762, January 2007,
<https://www.rfc-editor.org/info/rfc4762>.
[RFC4875] Aggarwal, R., Ed., Papadimitriou, D., Ed., and S.
Yasukawa, Ed., "Extensions to Resource Reservation
Protocol - Traffic Engineering (RSVP-TE) for Point-to-
Multipoint TE Label Switched Paths (LSPs)", RFC 4875,
DOI 10.17487/RFC4875, May 2007,
<https://www.rfc-editor.org/info/rfc4875>.
[RFC6388] Wijnands, IJ., Ed., Minei, I., Ed., Kompella, K., and B.
Thomas, "Label Distribution Protocol Extensions for Point-
to-Multipoint and Multipoint-to-Multipoint Label Switched
Paths", RFC 6388, DOI 10.17487/RFC6388, November 2011,
<https://www.rfc-editor.org/info/rfc6388>.
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[RFC7060] Napierala, M., Rosen, E., and IJ. Wijnands, "Using LDP
Multipoint Extensions on Targeted LDP Sessions", RFC 7060,
DOI 10.17487/RFC7060, November 2013,
<https://www.rfc-editor.org/info/rfc7060>.
[RFC7761] Fenner, B., Handley, M., Holbrook, H., Kouvelas, I.,
Parekh, R., Zhang, Z., and L. Zheng, "Protocol Independent
Multicast - Sparse Mode (PIM-SM): Protocol Specification
(Revised)", STD 83, RFC 7761, DOI 10.17487/RFC7761, March
2016, <https://www.rfc-editor.org/info/rfc7761>.
[RFC7988] Rosen, E., Ed., Subramanian, K., and Z. Zhang, "Ingress
Replication Tunnels in Multicast VPN", RFC 7988,
DOI 10.17487/RFC7988, October 2016,
<https://www.rfc-editor.org/info/rfc7988>.
Authors' Addresses
Zhaohui Zhang
Juniper Networks
EMail: zzhang@juniper.net
Santosh Esale
Juniper Networks, Inc.
EMail: sesale@juniper.net
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