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第三章
路由算法与路由协议(2)
Open Shortest Path First
Protocol (OSPF)
徐明伟
xmw@
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Overview
Introduction
Motivation
OSPF Basics
OSPF Operation
Hierarchical Routing in OSPF
Summary
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Overview
Introduction
Motivation
OSPF Basics
OSPF Operation
Hierarchical Routing in OSPF
Summary
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Introduction
OSPF: Open Shortest First Path protocol
Preferred IGP
Evolved from IS-IS protocol
Link state protocol
Distribution of LSAs using reliable flooding, LSA flooding is
bounded by area
Use IP as transport, IP protocol 89
Utilize IP multicast when sending/receiving the updates
- , All OSPF Routers
- , All DRs
Support for CIDR, Authentication and Multi-path
Employ Dijkstra’s Shortest Path First (SPF) algorithm to calculate
the path tree
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OSPF Development History
Development began in 1987
OSPF Working Group (part of IETF)
OSPFv2 first established in 1991
Many new features added since then (RFC 1247, RFC
1583, RFC2178)
Latest OSPFv2 specification is RFC 2328
OSPFv3 specification (for IPv6) in RFC 2740
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OSPF Development History (cont'd)
CIDR
1987 1989 1991 1993 1995 1997 1999
OSPF Group OSPFv2 Cryptographic OSPFv3
formed published auth
