|
The network shown in the figure demonstrates the use
of BGP peer groups. RTC has internal peering sessions with RTD, RTE, and RTH and
has similar policies towards each. Instead of formulating and applying similar
policies for each neighbor individually, RTC could define a peer group that
contains the policies, and then places its internal neighbors in the peer group.
Note: Click on topology to view command
outputs.
The configuration defines a peer group called
INTERNALMAP that contains the following policies:
- A route map named INTERNAL
- A filter list for outgoing updates (filter list
1)
- A filter list for incoming updates (filter list
2)
The configuration applies the peer group to all
internal neighbors -- RTD, RTE, and RTH. While members of a peer group inherit all
the configuration options of the peer group, they can also be configured to
override configuration options. That is, peer group members can be configured to
override policies inherited from the peer group. The configuration of RTC, for
example, also defines a filter-list 3 for incoming updates from the neighbor at
IP address 172.16.12.1 (RTH). Filter-list 3 will override any incoming policies
set by the peer group INTERNALMAP for neighbor RTH. The commands configure a BGP
peer group named EXTERNALMAP on RTC and apply it to the exterior neighbors in
AS3 and AS2:
In this configuration, the
neighbor
remote-as
router configuration commands are placed outside the
neighbor
peer-group
router configuration commands because different external ASs have to
be defined. Also note that this configuration defines filter-list 3, which can
be used to override configuration options for incoming updates from the neighbor
at IP address 172.16.20.3 (RTF).
 |
 |
Lab
Activity |
| |
In this lab,
you will learn how to configure a peer group to assign
policies to a group of BGP neighbors that share the same update
policies. |
|
|
|
|