Configuration Templates - Cisco ASR 9000 Series Routing Configuration Manual

BGP Configuration

Configuration Templates

The af-group, session-group, and neighbor-group configuration commands provide template support for
the neighbor configuration in Cisco IOS XR software.
The af-group command is used to group address family-specific neighbor commands within an IPv4, IPv6,
or VPNv4, address family. Neighbors that have the same address family configuration are able to use the
address family group (af-group) name for their address family-specific configuration. A neighbor inherits the
configuration from an address family group by way of the use command. If a neighbor is configured to use
an address family group, the neighbor (by default) inherits the entire configuration from the address family
group. However, a neighbor does not inherit all of the configuration from the address family group if items
are explicitly configured for the neighbor. The address family group configuration is entered under the BGP
router configuration mode. The following example shows how to enter address family group configuration
mode.
RP/0/RSP0/CPU0:router(config)# router bgp 140
RP/0/RSP0/CPU0:router(config-bgp)# af-group afmcast1 address-family ipv4 unicast
RP/0/RSP0/CPU0:router(config-bgp-afgrp)#
The session-group command allows you to create a session group from which neighbors can inherit address
family-independent configuration. A neighbor inherits the configuration from a session group by way of the
use command. If a neighbor is configured to use a session group, the neighbor (by default) inherits the entire
configuration of the session group. A neighbor does not inherit all of the configuration from a session group
if a configuration is done directly on that neighbor. The following example shows how to enter session group
configuration mode:
RP/0/RSP0/CPU0:router# router bgp 140
RP/0/RSP0/CPU0:router(config-bgp)# session-group session1
RP/0/RSP0/CPU0:router(config-bgp-sngrp)#
The neighbor-group command helps you apply the same configuration to one or more neighbors. Neighbor
groups can include session groups and address family groups and can comprise the complete configuration
for a neighbor. After a neighbor group is configured, a neighbor can inherit the configuration of the group
using the use command. If a neighbor is configured to use a neighbor group, the neighbor inherits the entire
BGP configuration of the neighbor group.
The following example shows how to enter neighbor group configuration mode:
RP/0/RSP0/CPU0:router(config)# router bgp 123
RP/0/RSP0/CPU0:router(config-bgp)# neighbor-group nbrgroup1
RP/0/RSP0/CPU0:router(config-bgp-nbrgrp)#
The following example shows how to enter neighbor group address family configuration mode:
RP/0/RSP0/CPU0:router(config)# router bgp 140
RP/0/RSP0/CPU0:router(config-bgp)# neighbor-group nbrgroup1
RP/0/RSP0/CPU0:router(config-bgp-nbrgrp)# address-family ipv4 unicast
RP/0/RSP0/CPU0:router(config-bgp-nbrgrp-af)#
• However, a neighbor does not inherit all of the configuration from the neighbor group if items are
explicitly configured for the neighbor. In addition, some part of the configuration of the neighbor group
could be hidden if a session group or address family group was also being used.
Configuration grouping has the following effects in Cisco IOS XR software:
Cisco ASR 9000 Series Aggregation Services Router Routing Configuration Guide, Release 5.3.x
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Implementing BGP