Restart Signaling for IS-IS
draft-ietf-lsr-isis-rfc5306bis-00

Document Type Active Internet-Draft (lsr WG)
Last updated 2018-10-02
Replaces draft-ginsberg-isis-rfc5306bis
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IS-IS for IP Internets                                       L. Ginsberg
Internet-Draft                                                  P. Wells
Obsoletes: 5306 (if approved)                        Cisco Systems, Inc.
Intended status: Standards Track                        October 01, 2018
Expires: April 4, 2019

                      Restart Signaling for IS-IS
                   draft-ietf-lsr-isis-rfc5306bis-00

Abstract

   This document describes a mechanism for a restarting router to signal
   to its neighbors that it is restarting, allowing them to reestablish
   their adjacencies without cycling through the down state, while still
   correctly initiating database synchronization.

   This document additionally describes a mechansim for a router to
   signal its neighbors that it is preparing to initiate a restart while
   maintaining forwarding plane state.  This allows the neighbors to
   maintain their adjacencies until the router has restarted, but also
   allows the neighbors to bring the adjacencies down in the event of
   other topology changes.

   This document additionally describes a mechanism for a restarting
   router to determine when it has achieved Link State Protocol Data
   Unit (LSP) database synchronization with its neighbors and a
   mechanism to optimize LSP database synchronization, while minimizing
   transient routing disruption when a router starts.

   This document obsoletes RFC 5306.

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

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
   Task Force (IETF).  Note that other groups may also distribute

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   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 4, 2019.

Copyright Notice

   Copyright (c) 2018 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
   (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
   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.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Approach  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Timers  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.2.  Restart TLV . . . . . . . . . . . . . . . . . . . . . . .   5
       2.2.1.  Use of RR and RA Bits . . . . . . . . . . . . . . . .   6
       2.2.2.  Use of the SA Bit . . . . . . . . . . . . . . . . . .   7
       2.2.3.  Use of PR and PA Bits . . . . . . . . . . . . . . . .   8
     2.3.  Adjacency (Re)Acquisition . . . . . . . . . . . . . . . .  10
       2.3.1.  Adjacency Reacquisition during Restart  . . . . . . .  10
       2.3.2.  Adjacency Acquisition during Start  . . . . . . . . .  12
       2.3.3.  Multiple Levels . . . . . . . . . . . . . . . . . . .  14
     2.4.  Database Synchronization  . . . . . . . . . . . . . . . .  14
       2.4.1.  LSP Generation and Flooding and SPF Computation . . .  15
   3.  State Tables  . . . . . . . . . . . . . . . . . . . . . . . .  17
     3.1.  Running Router  . . . . . . . . . . . . . . . . . . . . .  18
     3.2.  Restarting Router . . . . . . . . . . . . . . . . . . . .  18
     3.3.  Starting Router . . . . . . . . . . . . . . . . . . . . .  19
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  20
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  21
   6.  Manageability Considerations  . . . . . . . . . . . . . . . .  21
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  21

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