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The OSPF Not-So-Stubby Area (NSSA) Option (RFC3101)

IP.com Disclosure Number: IPCOM000010852D
Original Publication Date: 2003-Jan-01
Included in the Prior Art Database: 2003-Jan-28
Document File: 34 page(s) / 76K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

P. Murphy: AUTHOR

Abstract

This memo documents an optional type of Open Shortest Path First (OSPF) area that is somewhat humorously referred to as a "not-so- stubby" area (or NSSA). NSSAs are similar to the existing OSPF stub area configuration option but have the additional capability of importing AS external routes in a limited fashion.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 4% of the total text.

Network Working Group                                          P. Murphy

Request for Comments: 3101                          US Geological Survey

Obsoletes: 1587                                             January 2003

Category: Standards Track

               The OSPF Not-So-Stubby Area (NSSA) Option

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 optional type of Open Shortest Path First

   (OSPF) area that is somewhat humorously referred to as a "not-so-

   stubby" area (or NSSA).  NSSAs are similar to the existing OSPF stub

   area configuration option but have the additional capability of

   importing AS external routes in a limited fashion.

   The OSPF NSSA Option was originally defined in RFC 1587.  The

   functional differences between this memo and RFC 1587 are explained

   in Appendix F.  All differences, while expanding capability, are

   backward-compatible in nature.  Implementations of this memo and of

   RFC 1587 will interoperate.

Murphy                      Standards Track                     [Page 1]

RFC 3101       The OSPF Not-So-Stubby Area (NSSA) Option    January 2003

Table Of Contents

   1.0 Overview .................................................  2

      1.1 Motivation - Transit Networks .........................  2

      1.2 Motivation - Corporate Networks .......................  4

      1.3 Proposed Solution .....................................  5

   2.0 NSSA Intra-Area Implementation Details ...................  7

      2.1 The N-bit .............................................  7

      2.2 Type-7 Address Ranges .................................  7

      2.3 Type-7 LSAs ...........................................  8

      2.4 Originating Type-7 LSAs ...............................  9

      2.5 Calculating Type-7 AS External Routes ................. 10

      2.6 Incremental Updates ................................... 14

      2.7 Optionally Importing Summary Routes ................... 14

   3.0 Intra-AS Implementation Details .......................... 15

      3.1 Type-7 Translator Election ............................ 15

      3.2 Translating Type-7 LSAs into Type-5 LSAs .............. 16

      3.3 Flushing Translated Type-7 LSAs ....................... 19

   4.0 Security Considerations .................................. 20

   5.0 Acknowle...