PowerConnect B-Series FCX Configuration Guide 99353-1002266-01Basic configuration tasks 30Setting the local AS numberThe local AS number identifies the AS the Dell BGP4 router is in. The AS number can be from 1through 65535. There is no default. AS numbers 64512 through 65535 are the well-knownprivate 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 bgpBGP4: Please configure 'local-as' parameter in order to enable BGP4.PowerConnect(config-bgp-router)#local-as 10PowerConnect(config-bgp-router)#write memorySyntax: [no] local-as The parameter specifies the local AS number.Adding a loopback interfaceYou can configure the router to use a loopback interface instead of a specific port or virtual routinginterface to communicate with a BGP4 neighbor. A loopback interface adds stability to the networkby working around route flap problems that can occur due to unstable links between the router andits neighbors.Loopback interfaces are always up, regardless of the states of physical interfaces. Loopbackinterfaces are especially useful for IBGP neighbors (neighbors in the same AS) that are multiplehops away from the router. When you configure a BGP4 neighbor on the router, you can specifywhether the router uses the loopback interface to communicate with the neighbor. As long as apath exists between the router and its neighbor, BGP4 information can be exchanged. The BGP4session 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.NOTEIf you configure the Layer 3 Switch to use a loopback interface to communicate with a BGP4neighbor, the peer IP address on the remote router pointing to your loopback address must beconfigured.To add a loopback interface, enter commands such as those shown in the following example.PowerConnect(config-bgp-router)#exitPowerConnect(config)#int loopback 1PowerConnect(config-lbif-1)#ip address 10.0.0.1/24Syntax: interface loopback The value can be from 1 through 8 on Chassis Layer 3 Switches. The value can be from 1through 4 on the Compact Layer 3 Switch.Adding BGP4 neighborsThe BGP4 protocol does not contain a peer discovery process. Therefore, for each of the routerBGP4 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 withinthe same AS communicate using IBGP.
