Internet DRAFT - draft-filsfils-spring-analysis-fmwk-ext-srv6-encap
draft-filsfils-spring-analysis-fmwk-ext-srv6-encap
Network Working Group C. Filsfils
Internet-Draft D. Dukes, Ed.
Intended status: Informational Cisco Systems, Inc.
Expires: January 28, 2021 K. Patel
Arrcus, Inc.
July 27, 2020
Analysis Framework For Extensions of SRv6 Encapsulation
draft-filsfils-spring-analysis-fmwk-ext-srv6-encap-01
Abstract
This document provides a framework for analysis of multiple proposals
to extend SRv6 encapsulation with the objective of minimizing
encapsulation size or leveraging legacy equipment. It defines
relevant metrics to evaluate each proposal.
Requirements Language
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].
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
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This Internet-Draft will expire on January 28, 2021.
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2.1. Compliance . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Data Plane Efficiency . . . . . . . . . . . . . . . . . . 4
2.3. State Efficiency . . . . . . . . . . . . . . . . . . . . 4
2.4. Encapsulation Size . . . . . . . . . . . . . . . . . . . 4
3. Variables For Metrics . . . . . . . . . . . . . . . . . . . . 4
4. Analysis of Proposals . . . . . . . . . . . . . . . . . . . . 5
5. Normative References . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
Traffic traversing an SR domain is encapsulated in an outer IPv6
header with an optional Segment Routing Header (SRH) for its journey
through the SR domain [I-D.ietf-6man-segment-routing-header].
This document provides a framework for analysis of multiple proposals
to extend SRv6 encapsulation with the objective of minimizing
encapsulation size or leveraging legacy equipment. It defines
relevant metrics to evaluate each proposal.
Future revisions will evaluate and document the metrics for each
proposal, compare them and draw conclusions.
2. Metrics
Metrics are identified as metric:score. Metric is the abbreviation
of the metric name, and score is an integer reporting its evaluation.
A proposal with a metric (M) and score of zero is represented as M:0.
A score may vary based on the number and type of instructions in a
segment list. Three types of segments are considered: T for
topological, S for service, and V for VPN.
A proposal with a metric (M), computed for a segment list of 5
topological segments followed by 1 VPN segment, with a score of 10 is
represented as M(5T.1V):10.
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A score may vary based on node parameters. Three parameters are
considered: N the number of nodes in the network, I the number of IGP
algorithms [I-D.ietf-lsr-flex-algo] configured at the node, and A the
number of adjacency SIDs configured at the node.
A proposal with metric (M), computed for a node in a network of 100
nodes with 1 IGP algorithm and 5 adjacency SIDs configured at the
node, with a score of 10 is represented by M(100N.1I.5A):10.
2.1. Compliance
The compliance metric (C) records how aligned a proposal is with the
SRv6 solution.
o C.RFC8402: compliance with [RFC8402]
o C.SRH: compliance with [I-D.ietf-6man-segment-routing-header]
o C.PGM: compliance with [I-D.ietf-spring-srv6-network-programming]
o C.IGP: compliance with [I-D.ietf-lsr-isis-srv6-extensions]
o C.BGP: compliance with [I-D.ietf-bess-srv6-services]
o C.POL: compliance with [I-D.ietf-spring-segment-routing-policy]
o C.BLS: compliance with [I-D.ietf-idr-bgpls-srv6-ext]
o C.SVC: compliance with [I-D.ietf-spring-sr-service-programming]
o C.OAM: compliance with [I-D.ietf-6man-spring-srv6-oam]
Each of the above metrics are assigned a compliance value:
o 10: complies with the specification
o 5: extends the specification
o 0: redefines the specification
C.TOT is the sum of all C.* metrics listed above. It provides an
overall assessment of the proposal's alignment with the SRv6 RFCs and
working group drafts.
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2.2. Data Plane Efficiency
The data plane efficiency metric (D) records the data plane
forwarding efficiency of the proposed solution. Two separate metrics
are used:
o D.PRS(segment list): worst-case number of headers parsed during
processing of the segment list.
o D.LKU(segment list): worst-case number of FIB lookups during
processing of the segment list.
2.3. State Efficiency
The state efficiency metric (S) records the number of additional FIB
entries (states) required by the proposed solution.
o S(node parameters): the number of additional FIB entries for a
node, given a set of parameters.
2.4. Encapsulation Size
The encapsulation size metric (E) records the number of bytes
required for the proposals
o E(segment list): the number of bytes required to encapsulate a
packet traversing the SR domain with segment list applied at an SR
source node. Specifically, the number of bytes from the beginning
of the encapsulating IPv6 header to the beginning of the packet
traversing the SR domain, including any and all headers in
between.
3. Variables For Metrics
For the E, D.PRS, D.LKU metrics the following segment lists are used
during analysis.
o 5T.1V
o 10T.1V
o 15T.1V
o 5T.1S.5T.1V
o 4T.1S.4T.1S.4T.1V
This list may be updated in subsequent revisions of this document.
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For the S metric the following node parameters are used in analysis.
o 1500N.2I.100A
This list may be updated in subsequent revisions of this document.
4. Analysis of Proposals
To be completed in subsequent revisions of this document.
5. Normative References
[I-D.ietf-6man-segment-routing-header]
Filsfils, C., Dukes, D., Previdi, S., Leddy, J.,
Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
(SRH)", draft-ietf-6man-segment-routing-header-26 (work in
progress), October 2019.
[I-D.ietf-6man-spring-srv6-oam]
Ali, Z., Filsfils, C., Matsushima, S., Voyer, D., and M.
Chen, "Operations, Administration, and Maintenance (OAM)
in Segment Routing Networks with IPv6 Data plane (SRv6)",
draft-ietf-6man-spring-srv6-oam-07 (work in progress),
July 2020.
[I-D.ietf-bess-srv6-services]
Dawra, G., Filsfils, C., Raszuk, R., Decraene, B., Zhuang,
S., and J. Rabadan, "SRv6 BGP based Overlay services",
draft-ietf-bess-srv6-services-03 (work in progress), July
2020.
[I-D.ietf-idr-bgpls-srv6-ext]
Dawra, G., Filsfils, C., Talaulikar, K., Chen, M.,
daniel.bernier@bell.ca, d., and B. Decraene, "BGP Link
State Extensions for SRv6", draft-ietf-idr-bgpls-
srv6-ext-03 (work in progress), July 2020.
[I-D.ietf-lsr-flex-algo]
Psenak, P., Hegde, S., Filsfils, C., Talaulikar, K., and
A. Gulko, "IGP Flexible Algorithm", draft-ietf-lsr-flex-
algo-08 (work in progress), July 2020.
[I-D.ietf-lsr-isis-srv6-extensions]
Psenak, P., Filsfils, C., Bashandy, A., Decraene, B., and
Z. Hu, "IS-IS Extension to Support Segment Routing over
IPv6 Dataplane", draft-ietf-lsr-isis-srv6-extensions-08
(work in progress), April 2020.
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[I-D.ietf-spring-segment-routing-policy]
Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and
P. Mattes, "Segment Routing Policy Architecture", draft-
ietf-spring-segment-routing-policy-08 (work in progress),
July 2020.
[I-D.ietf-spring-sr-service-programming]
Clad, F., Xu, X., Filsfils, C., daniel.bernier@bell.ca,
d., Li, C., Decraene, B., Ma, S., Yadlapalli, C.,
Henderickx, W., and S. Salsano, "Service Programming with
Segment Routing", draft-ietf-spring-sr-service-
programming-02 (work in progress), March 2020.
[I-D.ietf-spring-srv6-network-programming]
Filsfils, C., Camarillo, P., Leddy, J., Voyer, D.,
Matsushima, S., and Z. Li, "SRv6 Network Programming",
draft-ietf-spring-srv6-network-programming-16 (work in
progress), June 2020.
[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>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
Authors' Addresses
Clarence Filsfils
Cisco Systems, Inc.
Belgium
Email: cfilsfil@cisco.com
Darren Dukes (editor)
Cisco Systems, Inc.
Ottawa
Canada
Email: ddukes@cisco.com
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Keyur Patel
Arrcus, Inc.
USA
Email: keyur@arrcus.com
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