Cisco Systems 78-11741-02 manual Invokes MD5 authentication on a TCP connection to a BGP, IPC-322

Configuring BGP

Configuring Advanced BGP Features

Command	Purpose
Router(config-router)# neighbor {ip-address	Invokes MD5 authentication on a TCP connection to a BGP
peer-group-name}password string	peer. You can enter a case-sensitive password of up to 25
	characters. The string can contain any alphanumeric
	characters, including spaces. A password cannot be
	configured in the number-space-anything format. The space
	after the number causes problems. You can also use any
	combination of the following symbolic characters along with
	alphanumeric characters:
	` ~ ! @ # $ % ^ & * ( ) - _ = + \ } ] { [ “ ‘ : ; / > < . , ?
	Caution	If the authentication string is configured
		incorrectly, the BGP peering session will not be
		established. We recommend that you enter the
		authentication string carefully and verify that the
		peering session is established after authentication
		is configured.
Router(config-router)# neighbor {ip-address	Applies a route map to incoming or outgoing routes.
peer-group-name}route-mapmap-name {in out}
Router(config-router)# neighbor {ip-address	Configures the software to start storing received updates.
peer-group-name}soft-reconfiguration inbound	This command requires at least one keyword. Currently the
	only keyword available is inbound, so the use of inbound is
	not optional.

If a peer group is not configured with a remote-as attribute, the members can be configured with the neighbor remote-asrouter configuration command. This command allows you to create peer groups containing eBGP neighbors.

You can customize inbound policies for peer group members (using, for example, a distribute list, route map, or filter list) because one identical copy of an update is sent to every member of a group. Therefore, neighbor options related to outgoing updates cannot be customized for peer group members.

External BGP peers normally must reside on a directly connected network. Sometimes it is useful to relax this restriction in order to test BGP; do so by specifying the neighbor ebgp-multihoprouter configuration command.

Note To avoid the accidental creation of loops through oscillating routes, the multihop session will not be established if the only route to the address of the multihop peer is the default route (0.0.0.0).

Members of a peer group can pass routes from one member of the peer group to another. For example, if router B is peering with routers A and C, router B can pass routes from router A to router C.

For iBGP, you might want to allow your BGP connections to stay up regardless of which interface is used to reach a neighbor. To enable this configuration, you first configure a loopback interface and assign it an IP address. Next, configure the BGP update source to be the loopback interface. Finally, configure your neighbor to use the address on the loopback interface. Now the iBGP session will be up as long as there is a route, regardless of any interface.

You can set the minimum interval of time between BGP routing updates.

Cisco IOS IP Configuration Guide

IPC-322