Dell PowerConnect FCS624S Configuration Guide - Page 1035

Basic configuration tasks 30 Setting the local AS number The local AS number identifies the AS the Dell BGP4 router is in. The AS number can be from 1 through 65535. There is no default. AS numbers 64512 through 65535 are the well-known private BGP4 AS numbers and are not advertised to the Internet community. To set the local AS number, enter commands such as the following. PowerConnect(config)#router bgp BGP4: Please configure 'local-as' parameter in order to enable BGP4. PowerConnect(config-bgp-router)#local-as 10 PowerConnect(config-bgp-router)#write memory Syntax: [no] local-as The parameter specifies the local AS number. Adding a loopback interface You can configure the router to use a loopback interface instead of a specific port or virtual routing interface to communicate with a BGP4 neighbor. A loopback interface adds stability to the network by working around route flap problems that can occur due to unstable links between the router and its neighbors. Loopback interfaces are always up, regardless of the states of physical interfaces. Loopback interfaces are especially useful for IBGP neighbors (neighbors in the same AS) that are multiple hops away from the router. When you configure a BGP4 neighbor on the router, you can specify whether the router uses the loopback interface to communicate with the neighbor. As long as a path exists between the router and its neighbor, BGP4 information can be exchanged. The BGP4 session is not associated with a specific link but instead is associated with the virtual interfaces. You can add up to 24 IP addresses to each loopback interface. NOTE If you configure the Layer 3 Switch to use a loopback interface to communicate with a BGP4 neighbor, the peer IP address on the remote router pointing to your loopback address must be configured. To add a loopback interface, enter commands such as those shown in the following example. PowerConnect(config-bgp-router)#exit PowerConnect(config)#int loopback 1 PowerConnect(config-lbif-1)#ip address 10.0.0.1/24 Syntax: interface loopback The value can be from 1 through 8 on Chassis Layer 3 Switches. The value can be from 1 through 4 on the Compact Layer 3 Switch. Adding BGP4 neighbors The BGP4 protocol does not contain a peer discovery process. Therefore, for each of the router BGP4 neighbors (peers), you must indicate the neighbor IP address and the AS each neighbor is in. Neighbors that are in different autonomous systems communicate using EBGP. Neighbors within the same AS communicate using IBGP. PowerConnect B-Series FCX Configuration Guide 993 53-1002266-01