Concept Guide
Example of Soft-recongration of a BGP Neighbor
The example enables inbound soft-reconguration for the neighbor 10.108.1.1. All updates received from this neighbor are stored unmodied,
regardless of the inbound policy. When inbound soft-reconguration is done later, the stored information is used to generate a new set of
inbound updates
DellEMC(conf)# router bgp 100
DellEMC(conf-router_bgp)# neighbor 10.108.1.1 remote-as 20
DellEMC(conf-router_bgp)# neighbor 10.108.1.1 soft-reconfiguration inbound
DellEMC(conf-router_bgp)# exit
Route-refresh
This section explains how the soft-reconguration and route-refresh works. Soft-reconguration has to be congured explicitly for a
neighbor unlike route refresh, which is automatically negotiated between BGP peers when establishing a peer session.
The route-refresh updates will be sent, only if the neighbor soft-reconfiguration inbound command is not congured in a
BGP neighbor and when you do a soft reset using clear ip bgp {neighbor-address | peer-group-name} soft in
command.
If the neighbor soft-reconfiguration inbound is already congured in the BGP neighbor, the route refresh updates will not be
sent. If you want to use route refresh updates instead, remove the neighbor soft-reconfiguration inbound conguration and
then you need to do a hard reset atleast once, using clear ip bgp {* | as-number | ipv4| ipv6 | neighbor-address
| peer-group-name} command. If you remove neighbor soft-reconfiguration inbound for an individual neighbor (not
part of peer-group), then doing hard reset for the individual neighbor is enough. If the neighbor is part of a peer-group and when
neighbor soft-reconfiguration inbound is removed from the peer group, we need to do a hard reset for the peer-group.
If neighbor soft-reconfiguration inbound command is not congured ever in the router, then doing a soft reset is enough for
the route refresh updates to be sent.
Route-refresh updates for IPv4 and IPv6 prexes
This section explains the route-refresh functionality in dierent combinations for IPv4 or IPv6 prex congured with IPv4 or IPv6
neighbors.
By default, the IPv4 prexes is sent for all the neighbors irrespective of IPv4 address family is enabled or disabled. Following are the
dierent scenarios during which the route-refresh message is sent for the corresponding neighbors:
By default, the route-refresh message for IPv4 prexes is sent for both the IPv4 and IPv6 neighbors. Following is an example conguration
in which IPv4 prexes are enabled by default and the corresponding route-refresh message:
DellEMC(conf-router_bgp)# show config
!
router bgp 100
redistribute connected
neighbor 20.1.1.2 remote-as 200
neighbor 20.1.1.2 no shutdown
neighbor 20::2 remote-as 200
neighbor 20::2 no shutdown
!
address-family ipv6 unicast
redistribute connected
exit-address-family
!
DellEMC(conf-router_bgp)#do clear ip bgp 20.1.1.2 soft in
May 8 15:28:11 : BGP: 20.1.1.2 sending ROUTE_REFRESH AFI/SAFI (1/1)
May 8 15:28:12 : BGP: 20.1.1.2 UPDATE rcvd packet len 56
May 8 15:28:12 : BGP: 20.1.1.2 rcvd UPDATE w/ attr: origin ?, path 200, nexthop 20.1.1.2,
metric 0,
196
Border Gateway Protocol (BGP)