Understanding BGP Command Scope

BGP commands can be sorted into the following categories, each of which has a different scope; that is, each configures parameters within a different area of applicability. Individual command descriptions in this chapter and in Configuring BGP-MPLS Applications, provide more information about command behavior.

• The commands listed in Table 6 configure parameters for the BGP process globally, regardless of address family.

  Table 6: Commands Affecting BGP Globally

  bgp advertise-inactive	bgp graceful-restart path-selection-defer-time
  bgp advertise best-external-to-internal	bgp graceful-restart restart-time
  bgp always-compare-med	bgp graceful-restart stalepaths-time
  bgp bestpath med confed	bgp log-neighbor-changes
  bgp bestpath missing-as-worst	bgp maxas-limit
  bgp client-to-client reflection	bgp redistribute-internal
  bgp cluster-id	bgp router-id
  bgp confederation identifier	bgp shutdown
  bgp confederation peers	ip bgp-community new-format
  bgp default local-preference	overload shutdown
  bgp default route-target filter	rib-out disable
  bgp enforce-first-as	router bgp
  bgp fast-external-fallover	timers bgp
  bgp graceful-restart

• The commands listed in Table 7 configure parameters for all address families within the current VRF context.

  Table 7: Commands Affecting All Address Families in a VRF

  distance bgp

  synchronization

• The commands listed in Table 8 configure parameters only for the current address family context.

  Table 8: Commands Affecting the Current Address Family

  address family	disable-dynamic-redistribute
  aggregate-address	external-paths
  auto-summary	ip route-type
  bgp dampening	maximum-paths
  bgp wait-on-end-of-rib	network
  check-vpn-next-hops	redistribute
  default-information originate	table-map

• The commands listed in Table 9 configure parameters for a peer or peer group, regardless of address family. If the peer or peer group is activated in more than one address family, the values are changed in all those address families. These commands are said to apply on a per-VRF basis. In the following example, EBGP multihop is configured for the session, but when you configure an address family, it is not available—that is, EBGP multihop is not configurable per address family:

  host1(config-router)#neighbor 10.1.3.4 remote-as 1234

  host1(config-router)#neighbor 10.2.3.4 ebgp-multihop 5

  host1(config-router)#address-family ipv4 multicast

  host1(config-router-af)#neighbor 10.2.3.4 ebgp-multihop ?

  % Invalid input detected at '^' marker.

  host1(config-router-af)#exit-address-family

  Table 9: Commands Affecting All Address Families for the Specified Peer or Peer Group

  neighbor advertisement-interval	neighbor maximum-update-size
  neighbor allow	neighbor passive
  neighbor bfd-liveness-detection	neighbor password
  neighbor capability	neighbor peer-type
  neighbor description	neighbor remote-as
  neighbor ebgp-multihop	neighbor rib-out disable
  neighbor graceful-restart	neighbor shutdown
  neighbor graceful-restart restart-time	neighbor site-of-origin
  neighbor graceful-restart stalepaths-time	neighbor timers
  neighbor ibgp-singlehop	neighbor update-source
  neighbor lenient	neighbor weight

• The commands listed in Table 10 configure parameters separately for each address family exchanged over the BGP session. If you configure these parameters for a peer or peer group that is activated in more than one address family, the values are affected only for the current address family. The inbound route map is such a parameter; the following example demonstrates that a BGP session can have a different inbound route map for each address family.

  host1(config-router)#neighbor 1.1.3.4 remote-as 1234

  host1(config-router)#neighbor 1.2.3.4 route-map ucast-map in

  host1(config-router)#address-family ipv4 multicast

  host1(config-router-af)#neighbor 1.2.3.4 activate

  host1(config-router-af)#neighbor 1.2.3.4 route-map mcast-map in

  host1(config-router-af)#exit-address-family

  Table 10: Commands Affecting Only the Current Address Family for the Specified Peer or Peer Group

  neighbor activate	neighbor peer-group
  neighbor advertise-map	neighbor prefix-list
  neighbor allowas-in	neighbor prefix-tree
  neighbor as-override	neighbor remote-private-as
  neighbor default-originate	neighbor route-map
  neighbor distribute-list	neighbor route-reflector-client
  neighbor filter-list	neighbor send-community
  neighbor local-as	neighbor send-label
  neighbor maximum-prefix	neighbor soft-reconfiguration inbound
  neighbor next-hop-self	neighbor unsuppress-map
  neighbor next-hop-unchanged

Copyright © 2008, Juniper Networks, Inc. All rights reserved. Trademark Notice.