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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...