Deployment Guide

Table Of Contents
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 {ipaddress | 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.
Following is the show running-config command output for the above configuration.
DellEMC# show running-config bgp
!
router bgp 655
bgp router-id 1.1.1.1
neighbor 10.1.1.2 remote-as 20
neighbor 10.1.1.2 auto-local-address
neighbor 10.1.1.2 no shutdown
!
address-family ipv6 unicast
neighbor 10.1.1.2 activate
Border Gateway Protocol (BGP)
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