H3C S7500 Series Ethernet Switches Operation Manual

Operation Manual – Routing Protocol
H3C S7500 Series Ethernet Switches Chapter 4 OSPF Configuration
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Chapter 4 OSPF Configuration
When configuring OSPF, go to these sections for information you are interested in:
z OSPF Overview
z OSPF Configuration Task List
z Displaying and Maintaining OSPF Configuration
z OSPF Configuration Example
z Troubleshooting OSPF Configuration
4.1 OSPF Overview
4.1.1 Introduction to OSPF
Open Shortest Path First (OSPF) is a link state interior gateway protocol developed
by IETF. At present, OSPF version 2 (RFC 2328) is used, which has the following
features:
z High applicability: OSPF supports networks of various sizes and can support up
to several hundred routers.
z Fast convergence: OSPF can transmit update packets instantly after network
topology changes for routing information synchronization in the autonomous
system (AS).
z Loop-free: OSPF computes routes with the Shortest Path Tree algorithm
according to the collected link states, so no loop routes are generated from the
algorithm itself.
z Area partition: OSPF allows an autonomous system network to be divided into
different areas for ease of management so that routing information transmitted
between the areas is abstracted further, thereby reducing network bandwidth
consumption.
z Equivalent route: OSPF supports multiple equivalent routes to the same
destination.
z Routing hierarchy: OSPF has a four-level routing hierarchy. It prioritizes the
routes as intra-area, inter-area, external type-1, and external type-2 routes.
z Authentication: OSPF supports interface-based packet authentication to
guarantee the security of route calculation.
z Multicast transmission: OSPF supports transmitting protocol packets in multicast
mode.
4.1.2 OSPF Route Calculation
The following is a simple process of how OSPF calculates routes when there is no
area partition: