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The OSPF NSSA Option (RFC1587)

IP.com Disclosure Number: IPCOM000002421D
Original Publication Date: 1994-Mar-01
Included in the Prior Art Database: 2000-Sep-12
Document File: 13 page(s) / 35K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

R. Coltun: AUTHOR [+2]

Abstract

This document describes a new optional type of OSPF area, 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 a ASCII Text document.
This is the abbreviated version, containing approximately 9% of the total text.

Network Working Group R. Coltun

Request for Comments: 1587 RainbowBridge Communications

Category: Standards Track V. Fuller

Stanford University

March 1994

The OSPF 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.

Table Of Contents

1.0 Abstract ................................................. 1

2.0 Overview ................................................. 2

2.1 Motivation ............................................... 2

2.2 Proposed Solution ........................................ 3

3.0 Implementation Details ................................... 5

3.1 The N-bit ................................................ 5

3.2 Type-7 Address Ranges .................................... 5

3.3 Type-7 LSAs .............................................. 5

3.4 Originating Type-7 LSAs .................................. 7

3.5 Calculating Type-7 AS External Routes .................... 8

3.6 Incremental Updates ...................................... 10

4.0 Originating Type-5 LSAs .................................. 10

4.1 Translating Type-7 LSAs .................................. 10

4.2 Flushing Translated Type-7 LSAs .......................... 13

5.0 Acknowledgements ......................................... 13

6.0 References ............................................... 13

7.0 Security Considerations .................................. 13

8.0 Authors' Addresses ....................................... 14

Appendix A: Type-7 LSA Packet Format ......................... 15

Appendix B: The Options Field ................................ 16

Appendix C: Configuration Parameters ......................... 17

1.0 Abstract

This document describes a new optional type of OSPF area, 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.

2.0 Overview

2.1 Motivation

Wide-area transit networks (such as the NSFNET regionals) often have

connections to moderately-complex "leaf" sites. A leaf site may have

multiple IP network numbers assigned to it.

Typically, one of the leaf site's networks is directly connected to a

router provided and administered by the transit network while the

others are distributed throughout and administered by the site. From

the transit network's perspective, all o...