LAG indication
draft-decraene-lsr-lag-indication-00

Document Type Active Internet-Draft (individual)
Authors Bruno Decraene  , Shraddha Hegde 
Last updated 2021-04-06
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Network Working Group                                        B. Decraene
Internet-Draft                                                    Orange
Intended status: Standards Track                                S. Hegde
Expires: October 8, 2021                           Juniper Networks Inc.
                                                           April 6, 2021

                             LAG indication
                  draft-decraene-lsr-lag-indication-00

Abstract

   This document defines a new link flag to advertise that a layer-three
   link is composed of multiple layer-two sub-links, such as when this
   link is a Link Aggregation Group (LAG).  This allows a large single
   flow (an elephant flow) to be aware that the link capacity will be
   lower than expected as this single flow is not load-balanced across
   the multiple layer-two sub-links.  A path computation logic may use
   that information to route that elephant flow along a different path.

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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   Internet-Drafts are draft documents valid for a maximum of six months
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   This Internet-Draft will expire on October 8, 2021.

Copyright Notice

   Copyright (c) 2021 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
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   (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

Decraene & Hegde         Expires October 8, 2021                [Page 1]
Internet-Draft               LAG indication                   April 2021

   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.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  Protocol extensions . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  IS-IS extension . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  OSPF extension  . . . . . . . . . . . . . . . . . . . . .   3
   3.  Operational considerations  . . . . . . . . . . . . . . . . .   3
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
     4.1.  IS-IS . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     4.2.  OSPF  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   4
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Appendix A.  Changes / Author Notes . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   An IP link may be composed a multiple layer two sub-links not visible
   to the IGP routing topology.  When traffic crossing that IP link is
   load-balanced on a per flow basis, a large elephant flow will only
   benefit from the capacity of a single sub-link.  This is an issue for
   the routing logic which only see the aggregated bandwidth of the IP
   link, and hence may incorrectly route a large flow over a link which
   is incapable of transporting that flow.

   This document defines a new link flag to signal that an IP link is a
   Link Aggregate Group composed of multiple layer two sub-links.  This
   flag may be automatically be set by routing nodes connected to such
   links, without requiring manual tagging by the network operator.  A
   path computation logic such as a PCE or a CSPF computation on the
   ingress, may use that information to avoid such links for elephant
   flows.

1.1.  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 RFC 2119 [RFC2119] RFC 8174 [RFC8174] when, and only when, they
   appear in all capitals, as shown here.
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