Peer Groups

Peer Groups
It is quite common for a BGP speaker to use the same update policies for its peers. An update
policy consists of the same outbound route maps, distribute lists, filter lists, update source, and
so on. Having to configure the same update policy on a BGP speaker for all of its neighbors can
become strenuous, and more important, when making modifications to the update policy, there
is room for errors. There is a way around this, and it’s known as peer groups. Peer groups allow
you to group all of a BGP speaker’s neighbors that need to use the same policy into one group.
The update policy is then applied to all members of that peer group.
A peer group update policy can contain any of the options listed in Table 9.1.
TABLE 9 . 1 Update Policy Options
Option Description
advertise-map Specifies the route map for conditional advertisement.
advertisement-interval Sets the minimum interval between sending eBGP
routing updates.
312 Chapter 9  Advanced Border Gateway Protocol
default-originate Originates the default route to this neighbor.
description Creates a neighbor-specific description.
inbound/outbound distribute-list Filters updates to/from this neighbor.
ebgp-multihop Allows eBGP neighbors not on directly connected
networks.
inbound/outbound filter-list Establishes BGP filters.
maximum-prefix Sets the maximum number of prefixes accepted from
this peer.
next-hop-self Disables the next-hop calculation for this neighbor.
password Sets a password.
inbound/outbound prefix-list Applies a prefix list to a neighbor.
remote-as Specifies a BGP neighbor.
remove-private-AS Removes a private AS number from outbound
updates.
inbound/outbound route-map Applies a route map to a neighbor.
route-reflector-client Configures a neighbor as a route reflector client.
send-community Sends the COMMUNITY attribute to this neighbor.
soft-reconfiguration Per neighbor soft reconfiguration.
timers Sets BGP per neighbor timers.
unsuppress-map Route map to selectively unsuppress suppressed
routes.
update-source Source of routing updates.
version Sets the BGP version to match a neighbor.
weight Sets the default weight for routes from this neighbor.