draft-ietf-lsvr-applicability-06.txt   draft-ietf-lsvr-applicability-07.txt 
LSVR K. Patel LSVR K. Patel
Internet-Draft Arrcus, Inc. Internet-Draft Arrcus, Inc.
Intended status: Informational A. Lindem Intended status: Informational A. Lindem
Expires: January 27, 2021 Cisco Systems Expires: March 25, 2021 Cisco Systems
S. Zandi S. Zandi
G. Dawra G. Dawra
Linkedin Linkedin
July 26, 2020 September 21, 2020
Usage and Applicability of Link State Vector Routing in Data Centers Usage and Applicability of Link State Vector Routing in Data Centers
draft-ietf-lsvr-applicability-06 draft-ietf-lsvr-applicability-07
Abstract Abstract
This document discusses the usage and applicability of Link State This document discusses the usage and applicability of Link State
Vector Routing (LSVR) extensions in data center networks utilizing Vector Routing (LSVR) extensions in data center networks utilizing
CLOS or Fat-Tree topologies. The document is intended to provide a CLOS or Fat-Tree topologies. The document is intended to provide a
simplified guide for the deployment of LSVR extensions. simplified guide for the deployment of LSVR extensions.
Status of This Memo Status of This Memo
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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 https://datatracker.ietf.org/drafts/current/. Drafts is at https://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 January 27, 2021. This Internet-Draft will expire on March 25, 2021.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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6.2.1. Sparse Peering Model 6.2.1. Sparse Peering Model
Alternately, BFD [RFC5580] can be used to swiftly determine the Alternately, BFD [RFC5580] can be used to swiftly determine the
availability of links and the BGP peering model can be significantly availability of links and the BGP peering model can be significantly
sparser than the data center fabric. BGP SPF sessions only need to sparser than the data center fabric. BGP SPF sessions only need to
be established with enough peers to provide a bi-connected graph. If be established with enough peers to provide a bi-connected graph. If
IEBGP is used, then the BGP routers at tier N-1 will act as route- IEBGP is used, then the BGP routers at tier N-1 will act as route-
reflectors for the routers at tier N. reflectors for the routers at tier N.
The obvious usage of sparse peering is to avoid parallel sessions on The obvious usage of sparse peering is to avoid parallel BGP sessions
links between the same two BGP speakers in the data center fabric. on links between the same two switches in the data center fabric.
However, this use case is not very useful since parallel layer-3 However, this use case is not very useful since parallel layer-3
links between the same two BGP routers are rare in CLOS or Fat-Tree links between the same two BGP routers are rare in CLOS or Fat-Tree
topologies. Two more interesting scenarios are described below. topologies. Additionally, when there are multiple links, they are
often aggregated at the link layer rather than the IP layer. Two
more interesting scenarios are described below.
In current data center topologies, there is often a very dense mesh In current data center topologies, there is often a very dense mesh
of links between levels, e.g., leaf and spine, providing 32-way, of links between levels, e.g., leaf and spine, providing 32-way,
64-way, or more Equal-Cost Multi-Path (ECMP) paths. In these 64-way, or more Equal-Cost Multi-Path (ECMP) paths. In these
topologies, it is desirable not to have a BGP session on every link topologies, it is desirable not to have a BGP session on every link
and techniques such as the one described in Section 6.2.2 can be used and techniques such as the one described in Section 6.2.2 can be used
establish sessions on some subset of northbound links. For example, establish sessions on some subset of northbound links. For example,
in a Spine-Leaf topology, each leaf switch would only peer with a in a Spine-Leaf topology, each leaf switch would only peer with a
subset of the spines dependent on the flooding redundancy required to subset of the spines dependent on the flooding redundancy required to
be reasonably certain that every node within the BGP-LS SPF routing be reasonably certain that every node within the BGP-LS SPF routing
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The authors would like to thank Alvaro Retana, Yan Filyurin, and The authors would like to thank Alvaro Retana, Yan Filyurin, and
Boris Hassanov for their review and comments. Boris Hassanov for their review and comments.
13. References 13. References
13.1. Normative References 13.1. Normative References
[I-D.ietf-lsvr-bgp-spf] [I-D.ietf-lsvr-bgp-spf]
Patel, K., Lindem, A., Zandi, S., and W. Henderickx, Patel, K., Lindem, A., Zandi, S., and W. Henderickx,
"Shortest Path Routing Extensions for BGP Protocol", "Shortest Path Routing Extensions for BGP Protocol",
draft-ietf-lsvr-bgp-spf-09 (work in progress), May 2020. draft-ietf-lsvr-bgp-spf-11 (work in progress), August
2020.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
skipping to change at page 12, line 35 skipping to change at page 12, line 40
(work in progress), June 2019. (work in progress), June 2019.
[I-D.ietf-lsr-dynamic-flooding] [I-D.ietf-lsr-dynamic-flooding]
Li, T., Psenak, P., Ginsberg, L., Chen, H., Przygienda, Li, T., Psenak, P., Ginsberg, L., Chen, H., Przygienda,
T., Cooper, D., Jalil, L., Dontula, S., and G. Mishra, T., Cooper, D., Jalil, L., Dontula, S., and G. Mishra,
"Dynamic Flooding on Dense Graphs", draft-ietf-lsr- "Dynamic Flooding on Dense Graphs", draft-ietf-lsr-
dynamic-flooding-07 (work in progress), June 2020. dynamic-flooding-07 (work in progress), June 2020.
[I-D.ietf-lsvr-l3dl] [I-D.ietf-lsvr-l3dl]
Bush, R., Austein, R., and K. Patel, "Layer 3 Discovery Bush, R., Austein, R., and K. Patel, "Layer 3 Discovery
and Liveness", draft-ietf-lsvr-l3dl-05 (work in progress), and Liveness", draft-ietf-lsvr-l3dl-06 (work in progress),
May 2020. July 2020.
[I-D.xu-idr-neighbor-autodiscovery] [I-D.xu-idr-neighbor-autodiscovery]
Xu, X., Talaulikar, K., Bi, K., Tantsura, J., and N. Xu, X., Talaulikar, K., Bi, K., Tantsura, J., and N.
Triantafillis, "BGP Neighbor Discovery", draft-xu-idr- Triantafillis, "BGP Neighbor Discovery", draft-xu-idr-
neighbor-autodiscovery-12 (work in progress), November neighbor-autodiscovery-12 (work in progress), November
2019. 2019.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
DOI 10.17487/RFC2328, April 1998, DOI 10.17487/RFC2328, April 1998,
<https://www.rfc-editor.org/info/rfc2328>. <https://www.rfc-editor.org/info/rfc2328>.
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