PIM WG Stig. Venaas
Internet-Draft Cisco Systems, Inc.
Intended status: Standards Track Zheng. Zhang
Expires: January 8, 2017 ZTE Corporation
July 7, 2016
PIM IGP EXT
draft-zhang-pim-igp-ext-01
Abstract
This document introduces a method to advertise multicast source
information. The information will be flooded all over the network by
OSPF, ISIS and Babel extension. This allows PIM Sparse Mode routers
with connected receivers to build a Shortest Path Tree straight away,
with no need for a shared a tree.
Status of This Memo
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This Internet-Draft will expire on January 8, 2017.
Copyright Notice
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Advertisement mechanism . . . . . . . . . . . . . . . . . . . 3
4. IGP extension . . . . . . . . . . . . . . . . . . . . . . . . 3
4.1. OSPF extension . . . . . . . . . . . . . . . . . . . . . 3
4.2. ISIS extension . . . . . . . . . . . . . . . . . . . . . 4
4.3. Babel extension . . . . . . . . . . . . . . . . . . . . . 4
5. Security Consideration . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7. Normative References . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Terminology
RP: Rendezvous Point.
RPF: Reverse Path Forwarding.
SPT: Shortest Path Tree.
FHR: First Hop Router, directly connected to the source.
LHR: Last Hop Router, directly connected to the receiver.
SG Mapping: Multicast source to group mapping.
MSGI: Multicast Source and group Information as abbreviation.
2. Introduction
[RFC4601] and [RFC7761] introduces that RP can be used to collect the
receiver and source information. Obviously, RP may be bottleneck in
some busy network. Though the RP-mapping mechanism [RFC6226] is used
to make different RP in charge of different groups, it makes the
network management more difficult and complex.
[I-D.ietf-pim-source-discovery-bsr] defines an effective way to
deliver multicast information by the way of PIM packet flooding.
This function is very useful in network with the routers that are all
credible and controllable.
Some routers may be attacked or forged in some networks. In these
networks, the source information announcement may be forged. There
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is authentication method in IGP advertisement, such as OSPF, ISIS and
Babel. Authentication can prevent a router from injecting messages
with non-existing multicast sources. So the source information
announcement may be carried in OSPF, ISIS and Babel extension.
3. Advertisement mechanism
OSPF and ISIS are deployed widely in internet. And the two protocols
are the most popular and important routing protocol. The flooding
feature is an effective way to advertise the change of network
topology. In order to advertise the MSGI, the IGP flooding feature
is beneficial to spread the information to PIM routers that have, or
potentially may have, connected receivers.
Babel [RFC6126] is a loop-avoiding distance-vector routing protocol
that is robust and efficient both in ordinary wired networks and in
wireless mesh networks. And multicast service is useful in wired
networks and wireless networks. [RFC7298] defines the authentication
method of Babel. Babel extension can be used to delivery MSGI.
When a router starts receiving packets from a directly connected
source, it should advertise a MSGI for the source in the IGP, and
keep doing so as long as the source is active. Along with the IGP
flooding, the MSGI will quickly spread all over the network.
All routers receive the advertisement of the MSGI after flooding. A
router that is a LHR, joins the SPT towards the announced source
according to standard PIM Sparse Mode procedures, by sending a join
to the RPF neighbor towards the source.
Routers that do not have any connected receivers store the MSGI, such
that they can immediately join the SPT if they later should become a
LHR.
4. IGP extension
4.1. OSPF extension
A new type of the OSPF Opaque LSA is defined for OSPF MSGI
capability. And the same for OSPFv2 and OSPFv3. The format is:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Group Address (Encoded-Group format) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Src Address (Encoded-Unicast format) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Type : The value is TBD. 12 or later digit can be used.
o Length: The length of the value.
o Group Address: The group we are announcing sources for. The
format for this address is given in the Encoded-Group format in
[RFC7761].
o Src Address: The source address for the corresponding group. The
format for these addresses is given in the Encoded-Unicast address
in [RFC7761].
The TLV repeats for many groups and groups. In the case where a
source stops sending, the FHR simply stops announcing the TLVs. Then
the other routers delete the source information.
4.2. ISIS extension
A new ISIS TLV is defined for the MSGI advertisement. The format of
the TLV is same as OSPF.
4.3. Babel extension
A new Babel TLV is defined for MSGI advertisement according to
[RFC7557]. The format is same as OSPF.
5. Security Consideration
OSPF and ISIS protocol have the capability of authentication. The
security function can be used unchanged for the MSGI advertisement.
The authentication method defined in Babel [RFC7298] can be used
unchanged for MSGI advertisement.
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6. IANA Considerations
A new OSPF Opaque LSA need to be added for carrying OSPF MSGI TLV.
A new MSGI TLV need to be added for ISIS MSGI advertisement.
A new Babel TLV is defined for MSGI advertisement according to
[RFC7557].
7. Normative References
[I-D.ietf-pim-source-discovery-bsr]
Wijnands, I., Venaas, S., Brig, M., and A. Jonasson, "PIM
flooding mechanism and source discovery", draft-ietf-pim-
source-discovery-bsr-04 (work in progress), March 2016.
[RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,
"Protocol Independent Multicast - Sparse Mode (PIM-SM):
Protocol Specification (Revised)", RFC 4601,
DOI 10.17487/RFC4601, August 2006,
<http://www.rfc-editor.org/info/rfc4601>.
[RFC6126] Chroboczek, J., "The Babel Routing Protocol", RFC 6126,
DOI 10.17487/RFC6126, April 2011,
<http://www.rfc-editor.org/info/rfc6126>.
[RFC6226] Joshi, B., Kessler, A., and D. McWalter, "PIM Group-to-
Rendezvous-Point Mapping", RFC 6226, DOI 10.17487/RFC6226,
May 2011, <http://www.rfc-editor.org/info/rfc6226>.
[RFC7298] Ovsienko, D., "Babel Hashed Message Authentication Code
(HMAC) Cryptographic Authentication", RFC 7298,
DOI 10.17487/RFC7298, July 2014,
<http://www.rfc-editor.org/info/rfc7298>.
[RFC7557] Chroboczek, J., "Extension Mechanism for the Babel Routing
Protocol", RFC 7557, DOI 10.17487/RFC7557, May 2015,
<http://www.rfc-editor.org/info/rfc7557>.
[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, <http://www.rfc-editor.org/info/rfc7761>.
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[RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and
S. Shaffer, "Extensions to OSPF for Advertising Optional
Router Capabilities", RFC 7770, DOI 10.17487/RFC7770,
February 2016, <http://www.rfc-editor.org/info/rfc7770>.
Authors' Addresses
Stig Venaas
Cisco Systems, Inc.
Tasman Drive
San Jose CA 95134
USA
Email: stig@cisco.com
Zheng(Sandy) Zhang
ZTE Corporation
No. 50 Software Ave, Yuhuatai Distinct
Nanjing
China
Email: zhang.zheng@zte.com.cn
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