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IPv6 BGP unreachable nexthop through loopback

Posted: Fri May 18, 2018 11:55 am
by godzillante
Hi,

I'm running v6.38.1 on a CCR1036 and have the following scenario (real addresses and AS obscured for privacy):

- loopback address set on a bridge
/ipv6 address add address=aaaa:bbbb:ffff::1/128 advertise=no interface=bridge_myprovider_ipv6

- static route to provider's loopback:
/ipv6 route
add !bgp-as-path !bgp-atomic-aggregate !bgp-communities !bgp-local-pref !bgp-med !bgp-origin !bgp-prepend !check-gateway \
    distance=1 dst-address=cccc:dddd:0:e::/128 gateway=fe80::aa:bb:cc:1%ether12_WAN-myprovider

I can ping the gateway without problems
> ping cccc:dddd:0:e::  
  SEQ HOST                                     SIZE TTL TIME  STATUS                                                                 
    0 cccc:dddd:0:e::                             56  55 30ms  echo reply                                                             
    1 cccc:dddd:0:e::                             56  55 30ms  echo reply                                                             
    sent=2 received=2 packet-loss=0% min-rtt=30ms avg-rtt=30ms max-rtt=30ms

But when I receive the default route via cccc:dddd:0:e:: (through multihop BGP), it's deemed "unreachable":
/ipv6 route print detail

[...]

1  Db  dst-address=2000::/3 gateway=cccc:dddd:0:e:: gateway-status=cccc:dddd:0:e:: unreachable distance=20 scope=40 target-scope=30 
        bgp-as-path="00000" bgp-origin=igp received-from=myprovider_IPv6_peer

What am I doing wrong?

Thanks!

Re: IPv6 BGP unreachable nexthop through loopback

Posted: Fri May 18, 2018 11:59 am
by mrz
Currently recursive routing will not work if gateway is link local address.

Re: IPv6 BGP unreachable nexthop through loopback

Posted: Fri May 18, 2018 12:17 pm
by godzillante
Currently recursive routing will not work if gateway is link local address.
thank you mrz. so what's a possible solution?
I have other peers which allow BGP through a /126 or /127 ptp, but this one provider is not going to allow me.

Re: IPv6 BGP unreachable nexthop through loopback

Posted: Fri May 18, 2018 3:07 pm
by patrick7
The solution offered by MikroTik: If you are lucky, it will be solved with RouterOS v7!
viewtopic.php?f=14&t=42268#p425845

Re: IPv6 BGP unreachable nexthop through loopback

Posted: Fri May 18, 2018 4:06 pm
by godzillante
The solution offered by MikroTik: If you are lucky, it will be solved with RouterOS v7!
viewtopic.php?f=14&t=42268#p425845

I was aware of that thread :lol: just hoping there might be some alternative solution... or even an hack :(

Re: IPv6 BGP unreachable nexthop through loopback

Posted: Fri May 18, 2018 5:18 pm
by sri2007
Or maybe the next solution will be to re-design using WANs only instead of loopbacks, at least until RouterOS 7 arrives :)

Re: IPv6 BGP unreachable nexthop through loopback

Posted: Sat Aug 04, 2018 11:07 am
by JimmyNyholm
Currently recursive routing will not work if gateway is link local address.
I'd say Recusive routing is totally broken for ipv6 in RosV6 having route coming in from ospfv3 process, ibgp session but MP bgp route can't get active because the gateway is unreachable according to the ipv6 route print where active (none) and print detail tells gateway unreachable, ping gateway from same cli works like a charm and is a globaly uninqe adress on a router several hops away.

So as we now have it. RouterOS can't be used for ipv6 and this is what holding us back implementing ipv6. FIX NOW!
I do not run the latest bugfix version on the router mentioned here but I have Also not seen anything in release notes stating that it would work with a later version.

Re: IPv6 BGP unreachable nexthop through loopback

Posted: Sat Aug 04, 2018 3:24 pm
by pe1chl
Unfortunately it looks like the IPv6 engineer at MikroTIk has retired or is on extended leave.
Some minor display issues aside, there have been no changes in IPv6 for a year and a half, and no appreciable feature changes for several years.
Even the features that have changed (the announcement of DNS via RA) are in a half-baked state.
New features introduced usually lack IPv6 support. It looks like IPv6 is not a topic at MikroTik, unfortunately.

Re: IPv6 BGP unreachable nexthop through loopback

Posted: Mon Aug 17, 2020 8:19 pm
by mafiosa
After banging my head for last 2 days finally I figured out that it is mikrotik's fault.