Internet DRAFT - draft-wang-idr-redistribute-route-originator
draft-wang-idr-redistribute-route-originator
TEAS Working Group A.Wang
Internet Draft China Telecom
Intended status: Standard Track February 12, 2018
Expires: August 11, 2018
Redistribute Route Originator Extend TLV for BGP-LS
draft-wang-idr-redistribute-route-originator-01.txt
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Abstract
This document describes one TLV extended for BGP-LS to transfer the
originator of redistributed routes in order to let the SDN
controller to deduce the network topology automatically under the
multi-domain environments.
This extension can expand the usage of BGP-LS protocol to multi-
domain; enable the network operator to collect the connection
relationship between different domains and then calculate the
overall network topology automatically based on the information
provided by BGP-LS protocol.
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Table of Contents
1. Introduction ................................................ 2
2. Conventions used in this document............................ 2
3. Multi-Domain Scenarios....................................... 2
3.1. Proposed Solution....................................... 3
3.2. Redistributed Routes Originator TLV .................... 3
3.3. Topology Reconstruction................................. 4
4. Security Considerations...................................... 4
5. IANA Considerations ......................................... 4
6. Conclusions ................................................. 4
7. References .................................................. 5
7.1. Normative References.................................... 5
7.2. Informative References.................................. 5
8. Acknowledgments ............................................. 5
1. Introduction
BGP-LS [RFC 7752] describes the methodology that using BGP protocol
to transfer the Link-State information. Such method can enable SDN
controller to collect the underlay network topology automatically,
but it can only get the information within one IGP domain. If the
operator has more than one IGP domain, and these domains interconnect
each other, there is no suitable TLV within current BGP-LS to
transfer the interconnect information.
This draft introduces one new TLV to extend the BGP-LS protocol to
transfer the key information related to the interconnect topology.
After that, the SDN controller can then deduce the multi-domain
topology automatically based on the information from BGP-LS protocol.
2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
3. Multi-Domain Scenarios.
Fig.1 illustrates the multi-domain scenarios that this draft
discussed. Normally, SDN Controller can get the topology of IGP A and
IGP B individually via the BGP-LS protocol, but it can't get the
topology connection information between these two IGP domains because
there is normally no IGP protocol run on the connected links.
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+--------------+
---|SDN Controller----
| +--------------+ |
| |
BGP-LS BGP-LS
| |
| |
------ ---
///- -\\\ //-- --\\
/ \ / \
| R3-------R1--|------|-T1-------T3 |
| | | |
| IGP A | | IGP B |
| | | |
| R4 ------R2--|------|-T2-------T4 |
\ / \ /
\\\- -/// \\-- --//
----- ---
Fig.1 Multi-Domain Scenarios
3.1. Proposed Solution.
To get the topology information between these two domains, we can use
the redistribute method to redistribute the connected links into the
IGP domain respectively. The prefix of the redistributed links will
then be gotten via the BGP-LS border router within each domain.
Although these border routers know where these redistributed prefixes
coming from, but they do not advertise such information to the BGP-LS
information collector.
3.2. Redistributed Routes Originator TLV
This draft proposes to define one new TLV to transfer such key
information; we call it "Redistributed Routes Originator" TLV. The
format of this TLV is illustrated below:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// Redistributed Routes Originator //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: should be allocated by IANA.
Length: 4 Bytes.
Redistributed Routes Originator: Router ID of the redistributed
routes.
This TLV should be coincided with the IGP Route Tag TLV or OSPF
Route Type TLV, because these two TLVs indicate the associated
prefixes redistributed via other protocols.
3.3. Topology Reconstruction.
When SDN Controller gets such information from BGP-LS protocol, it
should compares the proximity of the redistributed prefixes. If they
are under the same scope, then it should find the corresponding
associated "redistributed route originator" TLV, build the link
between these two originators.
After iterating the above procedures for all of the redistributed
prefixes, the SDN controller can then draw the connection topology
between different domains automatically.
4. Security Considerations
TBD
5. IANA Considerations
TBD
6. Conclusions
TBD
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7. References
7.1. Normative References
[RFC7752] H. Gredler, Ed., J. Medved, S. Previdi, A. Farrel, S. Ray,
"North-Bound Distribution of Link-State and Traffic Engineering (TE)
Information Using BGP ", RFC7752, March 2016,
https://tools.ietf.org/html/rfc7752
7.2. Informative References
8. Acknowledgments
TBD.
Authors' Addresses
Aijun Wang
China Telecom
Beiqijia Town, Changping District
Beijing,China
Email: wangaj.bri@chinatelecom.cn
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