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Understanding the network.pdf - Back to Home

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The command shown above sets up <strong>the</strong> peer-group and establishes it as an IBGP<br />

peer-group. The following command establishes all <strong>the</strong> members of <strong>the</strong> IBGP<br />

peer-group:<br />

asbr-b2(config-router)#neighbor 192.168.0.5 as30001<br />

asbr-b2(config-router)#neighbor 192.168.0.6 as30001<br />

asbr-b2(config-router)#neighbor 192.168.0.1 as30001<br />

asbr-b2(config-router)#neighbor 192.168.0.2 as30001<br />

asbr-b2(config-router)#neighbor 192.168.1.19 as30001<br />

The following command enables MD5 au<strong>the</strong>ntication (and <strong>the</strong> password) <strong>to</strong> be used<br />

when establishing BGP peer sessions:<br />

asbr-b2(config-router)#neighbor as30001 password as-30001<br />

It is also possible <strong>to</strong> enable filtering with . Additional options include router<br />

distribution, route-maps, version, advertisement interval—any configuration option<br />

that can be applied group-wide. It is also possible <strong>to</strong> override a peer-group option by<br />

configuring an option locally.<br />

After <strong>the</strong>y are configured, neighbor routers just create <strong>the</strong> same peer-group within<br />

<strong>the</strong>ir local BGP configuration using .<br />

Any member of <strong>the</strong> peer-group can make contributions <strong>to</strong> <strong>the</strong> group-wide<br />

configuration.<br />

NOTE<br />

An alternative <strong>to</strong> using weights is <strong>to</strong> use <strong>the</strong> administrative distances <strong>to</strong> determine<br />

route preference. With BGP, three distances are used: external, internal, and local.<br />

To change <strong>the</strong> distances from <strong>the</strong>ir default settings, use <strong>the</strong> BGP configuration<br />

subcommand . The range, in case<br />

you forgot, is 1 <strong>to</strong> 255.

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