Browse Prior Art Database

Graceful OSPF Restart (RFC3623)

IP.com Disclosure Number: IPCOM000020300D
Original Publication Date: 2003-Nov-01
Included in the Prior Art Database: 2003-Nov-12
Document File: 19 page(s) / 39K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

J. Moy: AUTHOR [+3]

Abstract

This memo documents an enhancement to the OSPF routing protocol, whereby an OSPF router can stay on the forwarding path even as its OSPF software is restarted. This is called "graceful restart" or "non-stop forwarding". A restarting router may not be capable of adjusting its forwarding in a timely manner when the network topology changes. In order to avoid the possible resulting routing loops, the procedure in this memo automatically reverts to a normal OSPF restart when such a topology change is detected, or when one or more of the restarting router's neighbors do not support the enhancements in this memo. Proper network operation during a graceful restart makes assumptions upon the operating environment of the restarting router; these assumptions are also documented.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 9% of the total text.

Network Working Group J. Moy

Request for Comments: 3623 Sycamore Networks

Category: Standards Track P. Pillay-Esnault

Juniper Networks

A. Lindem

Redback Networks

November 2003

Graceful OSPF Restart

Status of this Memo

This document specifies an Internet standards track protocol for the

Internet community, and requests discussion and suggestions for

improvements. Please refer to the current edition of the "Internet

Official Protocol Standards" (STD 1) for the standardization state

and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (2003). All Rights Reserved.

Abstract

This memo documents an enhancement to the OSPF routing protocol,

whereby an OSPF router can stay on the forwarding path even as its

OSPF software is restarted. This is called "graceful restart" or

"non-stop forwarding". A restarting router may not be capable of

adjusting its forwarding in a timely manner when the network topology

changes. In order to avoid the possible resulting routing loops, the

procedure in this memo automatically reverts to a normal OSPF restart

when such a topology change is detected, or when one or more of the

restarting router's neighbors do not support the enhancements in this

memo. Proper network operation during a graceful restart makes

assumptions upon the operating environment of the restarting router;

these assumptions are also documented.

Moy, et al. Standards Track [Page 1]

RFC 3623 Graceful OSPF Restart November 2003

Table of Contents

1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2. Operation of Restarting Router . . . . . . . . . . . . . . . . 3

2.1. Entering Graceful Restart. . . . . . . . . . . . . . . . 4

2.2. When to Exit Graceful Restart. . . . . . . . . . . . . . 5

2.3. Actions on Exiting Graceful Restart. . . . . . . . . . . 6

3. Operation of Helper Neighbor . . . . . . . . . . . . . . . . . 7

3.1. Entering Helper Mode . . . . . . . . . . . . . . . . . . 7

3.2. Exiting Helper Mode. . . . . . . . . . . . . . . . . . . 8

4. Backward Compatibility . . . . . . . . . . . . . . . . . . . . 9

5. Unplanned Outages. . . . . . . . . . . . . . . . . . . . . . . 10

6. Interaction with Traffic Engineering . . . . . . . . . . . . . 11

7. Possible Future Work . . . . . . . . . . . . . . . . . . . . . 11

8. Intellectual Property Rights Notice. . . . . . . . . . . . . . 11

9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11

9.1. Normative References . . . . . . . . . . . . . . . . . . 11

9.2. Informative References . . . . . . . . . . . . . . . . . 11

A. Grace-LSA Format . . . . . . . . . . . . . . . . . . . . . . . 13

B. Configurable Parameters. . . . . . . . . . . . . . . . . . . . 15

Security Considerations. . . . . . . . . . . . . . . . . . . . . . 16

Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . 16

Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17

Full Copyright Statement . . . . . . . . . . . . . . . ....