SR OS routers never send or receive VPN-IPv6 routes with 32-bit IPv4 next-hop addresses.
When a VPN-IPv6 BGP route is advertised to an EBGP peer, the next-hop-self command applies if the enable-inter-as-vpn command is configured or if the enable-subconfed-vpn-forwarding and the next-hop-self commands are configured toward the EBGP peer. Otherwise, there is no change to the next-hop. The next-hop-self command results in one of the following outcomes.
If the EBGP session uses IPv4 transport, then the BGP next-hop is set to the IPv4 local address used to set up the session but encoded as an IPv4-mapped IPv6 address (for example, with the IPv4 address in the least significant 32 bits of a ::FFFF/96 prefix).
If the EBGP session uses IPv6 transport and it is associated with an advertise-ipv6-next-hops vpn-ipv6 command, the BGP next-hop is set to the value of the IPv6 local address used to set up the session. Otherwise, the BGP next-hop is set to the IPv4 address of the system interface encoded as an IPv4-mapped IPv6 address (for example, with the IPv4 address in the least significant 32 bits of a ::FFFF/96 prefix).
If the enable-inter-as-vpn command is configured, the next-hop-self command applies automatically if a VPN-IPv6 BGP route is received from an EBGP peer and re-advertised to an IBGP or confederation-EBGP peer. If the enable-inter-as-vpn command is not configured but the enable-subconfed-vpn-forwarding command is configured, the next-hop can be set manually toward any IBGP or confederation EBGP peer, with the same label-swap forwarding behavior as provided by the enable-inter-as-vpn command. In either case, the next-hop-self command results in one of the following outcomes.
If the IBGP or confederation EBGP session uses IPv4 transport, then the BGP next-hop is set to the IPv4 local address used to set up the session but encoded as an IPv4-mapped IPv6 address (for example, with the IPv4 address in the least significant 32 bits of a ::FFFF/96 prefix).
If the IBGP or confederation EBGP session uses IPv6 transport and it is associated with an advertise-ipv6-next-hops vpn-ipv6 command, then the BGP next-hop is set to the value of the IPv6 local address used to set up the session. Otherwise, the BGP next-hop is set to the IPv4 address of the system interface encoded as an IPv4-mapped IPv6 address (for example, with the IPv4 address in the least significant 32 bits of a ::FFFF/96 prefix).
When a VPN-IPv6 BGP route is reflected from one IBGP peer to another IBGP peer, the RR does not modify the next-hop by default. However, if the next-hop-self command is applied to the IBGP peer receiving the route and the enable-rr-vpn-forwarding command is configured, a next-hop-self command and label swap behavior can be provided. Alternatively, the same behavior can be achieved by configuring the enable-subconfed-vpn-forwarding command and setting the next-hop-self command toward the targeted IBGP peer. In either case, the next-hop-self command results in one of the following outcomes.
If the IBGP session receiving the reflected route uses IPv4 transport then the BGP next-hop is set to the IPv4 local-address used to set up the session but encoded as an IPv4-mapped IPv6 address (for example, with the IPv4 address in the least significant 32 bits of a ::FFFF/96 prefix).
If the IBGP session receiving the reflected route uses IPv6 transport and it is associated with an advertise-ipv6-next-hops vpn-ipv6 command, the BGP next-hop is set to the value of the IPv6 local address used for set up of the session. Otherwise, the BGP next-hop is set to the IPv4 address of the system interface encoded as an IPv4-mapped IPv6 address (for example, with the IPv4 address in the least significant 32 bits of a ::FFFF/96 prefix).
When a VPN-IPv6 BGP route is reflected from one IBGP peer to another IBGP peer, enable-rr-vpn-forwarding command is configured and the VPN-IPv6 route is matched and accepted by an export policy entry with a next-hop <ip-address> action, this changes the BGP next-hop of the matched routes to <ip-address> if it is specified as a 128-bit IPv6 address, or to an IPv4-mapped IPv6 address encoding <ip-address> if it is specified as a 32-bit IPv4 address.