Routing Protocol Overview; Static Routing And Dynamic Routing; Routing Protocols And Routing Priority; Displaying And Maintaining A Routing Table - 3Com 4510G Configuration Manual

Routing Protocol Overview

Static Routing and Dynamic Routing

Static routing is easy to configure and requires less system resources. It works well in small, stable
networks with simple topologies. Its major drawback is that you must perform routing configuration
again whenever the network topology changes; it cannot adjust to network changes by itself.
Dynamic routing is based on dynamic routing protocols, which can detect network topology changes
and recalculate the routes accordingly. Therefore, dynamic routing is suitable for large networks. Its
disadvantages are that it is difficult to configure, and that it not only imposes higher requirements on
the system, but also consumes a certain amount of network resources.

Routing Protocols and Routing Priority

Different routing protocols may find different routes to the same destination. However, not all of those
routes are optimal. In fact, at a particular moment, only one protocol can uniquely determine the
current optimal route to the destination. For the purpose of route selection, each routing protocol
(including static routes) is assigned a priority. The route found by the routing protocol with the highest
priority is preferred.
The following table lists some routing protocols and the default priorities for routes found by them:
Routing approach
DIRECT
STATIC
RIP
UNKNOWN
The smaller the priority value, the higher the priority.
The priority for a direct route is always 0, which you cannot change. Any other type of routes can
have their priorities manually configured.
Each static route can be configured with a different priority.
IPv4 and IPv6 routes have their own respective routing tables.

Displaying and Maintaining a Routing Table

To do...
Display brief information about
the active routes in the routing
table
Display information about
routes to the specified
destination
0
60
100
256
Use the command...
display ip routing-table [ verbose | | { begin
| exclude | include } regular-expression ]
display ip routing-table ip-address
[ mask-length | mask ] [ longer-match ]
[ verbose ]
1-3
Priority
Remarks
Available in any
view
Available in any
view