Internet DRAFT - draft-cheng-pals-p2p-pw-multicast
draft-cheng-pals-p2p-pw-multicast
PALS W. Cheng
Internet-Draft China Mobile
Intended status: Informational J. Dong
Expires: May 21, 2020 Huawei Technologies
November 18, 2019
Efficient Layer 2 Multicast with Point-to-Point Pseudowires
draft-cheng-pals-p2p-pw-multicast-01
Abstract
Multicast services such as Evolved Multimedia Broadcast/Multicast
Service (eMBMS) become more and more popular in mobile networks. In
mobile transport network, it is important for the operators to
provide efficient transport of multicast services with existing
network devices. This document describes a mechanism of using point-
to-point Pseudowires (PW) [RFC3985] to achieve efficient layer 2
multicast transportation in mobile transport networks.The document
gives a multicast method by utilizing a Point-to-Point (P2P) path
between nodes in a packet transport network , according to the
destination IP address. With it, the PTN nodes can replicate and
forward the service message, which are received from the multicast
server, to the plurality of multicast clients corresponding to the
destination IP address.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 21, 2020.
Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved.
Cheng & Dong Expires May 21, 2020 [Page 1]
Internet-DraftEfficient Layer 2 Multicast with Point-to-PoiNovember 2019
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions used in this document . . . . . . . . . . . . 3
1.1.1. Terminology . . . . . . . . . . . . . . . . . . . . . 3
1.1.2. Requirements Language . . . . . . . . . . . . . . . . 4
2. Efficient Multicast with P2P PWs . . . . . . . . . . . . . . 4
3. Protection Mechanism . . . . . . . . . . . . . . . . . . . . 4
4. OAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
8. Normative References . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
Multicast services such as evolved Multimedia Broadcast/Multicast
Service (eMBMS) become more and more popular in mobile networks. In
mobile transport network, it is important for the operators to
provide efficient transport of multicast services with existing
network devices.
Cheng & Dong Expires May 21, 2020 [Page 2]
Internet-DraftEfficient Layer 2 Multicast with Point-to-PoiNovember 2019
----------------
///// multicast \\\\\
// source \\
| |
| Layer 3 Multicast Network |
| |
\\ //
\\\\\ /////
+--+--+ +--+--+
| R-1 +-----+ R-2 |
+--+--+ +--+--+ L2
| |
+--+--+ +--+--+ Multicast
| R-3 +-----+-R-4 |
*---+-+ +-+---* Network
/ | | \
/ | | \
+-----+ +--+--+ +--+--+ +-----+
| R-5 +--+ R-6 | | R-7 +--+ R-8 |
+---+-+ +-+-+-+ +-+-+-+ +-+---+
/ | | | | | | \
/ | | | | | | \
Clients Clients Clients Clients
Figure 1. L2 Multicast Topology
PTN network comprise at least one root node and at least one leaf
node, the multicast source server is connected to the root node, and
the multicast clients are connected to the leaf node.Figure 1 shows a
typical topology of mobile transport network, which is composed of
the layer 3 network at the core and the layer 2 network at the
aggregation and edge. R-1 and R-2 connect to the upstream layer 3
network, in which the multicast source locates. This document
focuses on the efficient multicast service transportation in the
layer 2 segment of the network using point-to- point (P2P)
Pseudowires (PW) [RFC3985].
1.1. Conventions used in this document
1.1.1. Terminology
The terminology is defined as [RFC3985] .
Cheng & Dong Expires May 21, 2020 [Page 3]
Internet-DraftEfficient Layer 2 Multicast with Point-to-PoiNovember 2019
1.1.2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Efficient Multicast with P2P PWs
This section describes the mechanism of efficient layer 2 multicast
transportation with point-to-point PWs.
In the layer 2 multicast segment, nodes which connect to the L3
network are called Root nodes, and nodes which connect to the
multicast clients are called Leaf nodes. For each multicast service,
between the Root nodes and the Leaf nodes, 1-hop P2P PWs are
provisioned between the adjacent nodes. The multicast tree from the
Root nodes to the Leaf nodes is the concatenation of P2P PWs
provisioned by NMS or central controller.
Multicast traffic is carried by the P2P PWs. On each PW hop, the PW
label is popped, and the forwarding is performed according to the
layer 2 multicast forwarding table of the node. The layer 2
multicast forwarding entries can be either statically provisioned by
NMS or central controller, or dynamically generated via IGMP snooping
[RFC4541]. For multicast traffic received on a specific P2P PW, the
outbound PWs and ACs are determined by the corresponding L2 multicast
forwarding table. For packets to be forwarded to next P2P PW, the PW
label is pushed according to the forwarding table. With this
mechanism, on each P2P PW in the network, at most one copy of the
multicast traffic is delivered.
On the Leaf nodes, IGMP snooping [RFC4541] is used to optimize the
layer 2 multicast forwarding to the clients, so that only the clients
which express interests to the multicast service would receive the
corresponding multicast traffic.
3. Protection Mechanism
For layer 2 multicast service, 1+1 protection is provided. The
working and protection multicast trees are provisioned seperately by
NMS or central controller, and multicast service is carried on both
the working mutlicast tree and the protection multicast tree
simultaneously. In network topology of Figure 1, the Root node of
the working PW is R-1, while the Root node of the protection PW is
R-2. Each Leaf node has a working PW from its working upstream, and
a protection PW from the protection upstream. According to the
Cheng & Dong Expires May 21, 2020 [Page 4]
Internet-DraftEfficient Layer 2 Multicast with Point-to-PoiNovember 2019
result of OAM detection mechanism, the Leaf nodes choose to receive
multicast traffic from either the working or protection PW.
4. OAM
PW OAM mechanisms as defined in [RFC5085] [RFC6428] are deployed on
each P2P PW, including both the working PWs and protection PWs. When
failure occurs on a working PW, the node which detects the failure
SHOULD send AIS message as defined in [RFC6427] to notify its
downstream nodes of the failure. This AIS message is propagated
along the multicast tree to the downstream Leaf nodes. Then the Leaf
nodes which are impacted by the failure can switchover to receive the
multicast service traffic from the protection PWs
5. IANA Considerations
This document makes no request of IANA.
Note to RFC Editor: this section may be removed on publication as an
RFC.
6. Security Considerations
This document describes a layer 2 multicst mechansim with point-to-
point PWs and NMS or controller provisioned multicast tree. The
security condierations as specified in [RFC3985] apply to this
document.
7. Acknowledgements
The authors would like to thank Jun Wu, Kai Liu and Yongjian Hu for
the review and comments.
8. Normative References
[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>.
[RFC3985] Bryant, S., Ed. and P. Pate, Ed., "Pseudo Wire Emulation
Edge-to-Edge (PWE3) Architecture", RFC 3985,
DOI 10.17487/RFC3985, March 2005,
<https://www.rfc-editor.org/info/rfc3985>.
Cheng & Dong Expires May 21, 2020 [Page 5]
Internet-DraftEfficient Layer 2 Multicast with Point-to-PoiNovember 2019
[RFC4541] Christensen, M., Kimball, K., and F. Solensky,
"Considerations for Internet Group Management Protocol
(IGMP) and Multicast Listener Discovery (MLD) Snooping
Switches", RFC 4541, DOI 10.17487/RFC4541, May 2006,
<https://www.rfc-editor.org/info/rfc4541>.
[RFC5085] Nadeau, T., Ed. and C. Pignataro, Ed., "Pseudowire Virtual
Circuit Connectivity Verification (VCCV): A Control
Channel for Pseudowires", RFC 5085, DOI 10.17487/RFC5085,
December 2007, <https://www.rfc-editor.org/info/rfc5085>.
[RFC6427] Swallow, G., Ed., Fulignoli, A., Ed., Vigoureux, M., Ed.,
Boutros, S., and D. Ward, "MPLS Fault Management
Operations, Administration, and Maintenance (OAM)",
RFC 6427, DOI 10.17487/RFC6427, November 2011,
<https://www.rfc-editor.org/info/rfc6427>.
[RFC6428] Allan, D., Ed., Swallow, G., Ed., and J. Drake, Ed.,
"Proactive Connectivity Verification, Continuity Check,
and Remote Defect Indication for the MPLS Transport
Profile", RFC 6428, DOI 10.17487/RFC6428, November 2011,
<https://www.rfc-editor.org/info/rfc6428>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
Authors' Addresses
Weiqiang Cheng
China Mobile
Beijing
China
Email: chengweiqiang@chinamobile.com
Jie Dong
Huawei Technologies
China
Email: jie.dong@huawei.com
Cheng & Dong Expires May 21, 2020 [Page 6]
