RFC 5549 - IPv4 Routes with IPv6 next-hop - Does it really exists?

Wed Jul 29 09:57:57 UTC 2020

 ❦ 29 juillet 2020 12:13 +03, Saku Ytti:

>> This is the solution Cumulus is advocating to its users, so I suppose
>> they have some real users behind that. Juniper also supports RFC 5549
>> but, from the documentation, the forwarding part is done using
>> lightweight tunnels.
>
> I'm not sure if you claim otherwise, but no real 'tunneling' takes
> place, as far as I know, it's internal implementation detail having
> IPV6 next-hop for IPV4. I don't think there is any additional headers
> or any additional lookup or cost.

I didn't test, but the documentation states:

> Starting in Release 17.3R1, Junos OS devices can forward IPv4 traffic
> over an IPv6-only network, which generally cannot forward IPv4
> traffic. As described in RFC 5549, IPv4 traffic is tunneled from CPE
> devices to IPv4-over-IPv6 gateways. These gateways are announced to
> CPE devices through anycast addresses. The gateway devices then create
> dynamic IPv4-over-IPv6 tunnels to remote customer premises equipment
> and advertise IPv4 aggregate routes to steer traffic. Route reflectors
> with programmable interfaces inject the tunnel information into the
> network. The route reflectors are connected through IBGP to gateway
> routers, which advertise the IPv4 addresses of host routes with IPv6
> addresses as the next hop.

https://www.juniper.net/documentation/en_US/junos/topics/topic-map/multiprotocol-bgp.html#id-configuring-bgp-to-redistribute-ipv4-routes-with-ipv6-next-hop-addresses

If you have a pointer around the subject on Juniper, I would be quite
interested!

Thanks.
-- 
Write and test a big program in small pieces.
            - The Elements of Programming Style (Kernighan & Plauger)