H3C Technologies H3C SecPath F1000-E - Manual (Page 296)

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OSPF Configuration
Open Shortest Path First (OSPF) is a link state interior gateway protocol developed by the OSPF working
group of the Internet Engineering Task Force (IETF). At present, OSPF version 2 (RFC2328) is used.
NOTE:
The term router in this document refers to both routers and Layer 3 switches.
OSPF Overview
NOTE:
Unless otherwise noted, OSPF refers to OSPFv2 throughout this document.
OSPF has the following features:
• Wide scope: Supports networks of various sizes and up to several hundred routers in an OSPF
routing domain.
• Fast convergence: Transmits updates instantly after network topology changes for routing
information synchronization in the AS.
• Loop-free: Computes routes with the shortest path first (SPF) algorithm according to collected link
states, so no route loops are generated.
• Area partition: Allows an AS to be split into different areas for ease of management and routing
information transmitted between areas is summarized to reduce network bandwidth consumption.
• Equal-cost multi-route: Supports multiple equal-cost routes to a destination.
• Routing hierarchy: Supports a four-level routing hierarchy that prioritizes routes into intra-area,
inter-area, external Type-1, and external Type-2 routes.
• Authentication: Supports interface-based packet authentication to ensure the security of packet
exchange.
• Multicast: Supports multicasting protocol packets on some types of links.
Basic Concepts
Autonomous System
A set of routers using the same routing protocol to exchange routing information constitute an
Autonomous System (AS).
OSPF route computation
• OSPF route computation is described as follows:
• Based on the network topology around itself, each router generates Link State Advertisements (LSA)
and sends them to other routers in update packets.