Administrator Guide

20.20.20.1 10 10 20 0 0 0 00:06:11 0
R2#
Following is the output of show ip bgp ipv6 unicast summary command for the above configuration example.
R2#show ip bgp ipv6 unicast summary
BGP router identifier 2.2.2.2, local AS number 200
BGP local RIB : Routes to be Added 0, Replaced 0, Withdrawn 0
2 neighbor(s) using 24576 bytes of memory
Neighbor AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/Pfx
20.20.20.1 10 10 20 0 0 0 00:06:11 0
2001::1 10 40 45 0 0 0 00:03:14 0
R2#
Configure IPv6 NH Automatically for IPv6 Prefix
Advertised over IPv4 Neighbor
You can configure the system to pick the next hop IPv6 address dynamically for IPv6 prefix advertised over an IPv4 neighbor configured
under IPv6 address family. If there is no IPv6 address configured on the local interface, the system uses the IPv4 mapped IPv6 address. If
there are multiple IPv6 addresses configured on the interface, the system uses the lowest IPv6 address configured on that interface. If
the configuration is already present and a new IPv6 address, which is lower than the lowest existing address, is assigned to one of the
peer interfaces, that address is not used as the NH until you flap the interface manually.
Figure 26. Configure IPv6 NH to advertise IPv6 prefix over IPv4 neighbor
To enable BGP to pick the next hop IPv6 address automatically for IPv6 prefix advertised over an IPv4 neighbor, use the following
commands.
• Enable the system to pick the next hop IPv6 address dynamically for IPv6 prefix advertised over an IPv4 neighbor.
ROUTER-BGP mode mode
neighbor {ip–address | peer-group-name} auto-local-address
Enter either the neighbor IP address or the name of the peer group.
NOTE: If outbound policy is applied along with auto-local-address enabled, then policy takes precedence.
The following example configuration demonstrates how to configure BGP to automatically pick IPv6 address for IPv6 prefix advertised
over an IPv4 neighbor.
Example configuration performed in R1
DellEMC# configure terminal
DellEMC(conf)# router bgp 655
DellEMC(conf-router_bgp)# neighbor 10.1.1.2 remote-as 20
DellEMC(conf-router_bgp)# neighbor 10.1.1.2 auto-local-address
DellEMC(conf-router_bgp)# neighbor 10.1.1.2 no shutdown
DellEMC(conf-router_bgp)# bgp router-id 1.1.1.1
DellEMC(conf-router_bgp)# address-family ipv6 unicast
DellEMC(conf-router_bgpv6_af)# neighbor 10.1.1.2 activate
DellECM(conf-router_bgpv6_af)# exit
Configuring the auto-local-address for a neighbor will dynamically pick the local BGP interface IPv6 address (2001::1/64) as a the next hop
for all the updates over IPv4 neighbor configured under IPv6 address family. If the auto-local-address is not configured, the IPv4 mapped
IPv6 address (10.1.1.1) as a next hop.
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Border Gateway Protocol (BGP)