Opened 4 years ago

Closed 4 years ago

Last modified 4 years ago

#14207 closed defect (worksforme)

ip6gw ignored on routing but not for local gw

Reported by: gustik@… Owned by: developers
Priority: low Milestone: Chaos Calmer 15.05
Component: kernel Version: Trunk
Keywords: Cc:


Hi folks,

i have that TL-WR741ND/ar71xx with an OpenWRT firmware trunk from 18. September 2013. I have set up IPv6 statically using ipv6addr and ip6gw, but that is not important.

the PROBLEM now is:
he sets the default gateway but it only works for the router(locally), but not for the machines behind it (that are routed through/ip6forwarding).
i can see the default route using route -A inet6 and also in /proc/net/ipv6_route, but not with ip -6 route list. ip -6 route list shows no default gw for ipv6.

well, i can add a ip -6 route add default via "route" dev eth1 and then also the routing for the machines connected to br-lan works again.
ip -6 route list shows that default gw once. route -A inet6 and /proc/net/ipv6_route shows it twice.

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Change History (3)

comment:1 Changed 4 years ago by jow

IPv6 default routes are installed in the non-main table in order to properly accomodate for multihoming.

You can probably find your route with "ip -6 r s t all"

comment:2 Changed 4 years ago by cyrus

  • Resolution set to worksforme
  • Status changed from new to closed

For IPv6 interfaces the default route is only reachable from the IPv6-prefix configured on the interface itself. This is required to handle potential ingress filtering on your upstream connection (e.g. your upstream discarding packages with the wrong source address). Remember there is no NAT anymore ;)

If you want downstream clients / routers to use these routes as well you could define a delegated prefix in the ip6prefix option of that interface (recommended) which can then be automatically distributed onto downstream interfaces or you could as a fallback solution set "option ip6table main" in the interface config to disable source-restrictions for routes and put the routes in the main table again (not recommended).

See for details about the new IPv6 stack.

comment:3 Changed 4 years ago by Lars Schotte <gustik@…>

OK, i see your point. I think you mean this one:

option ip6prefix 2001:db80:1::/48 # Prefix addresses for distribution to downstream interfaces

in the options there is:
ip6prefix ipv6 prefix no (none) IPv6 prefix routed here for use on other interfaces (Barrier Breaker and later only)
so i could not have known it before, because i was first time using trunk.

however, it would be helpful to describe this a little bit more, because its not that i missed that point, i just did think that that option is needed on a different router (one hop upstream) and that is still running AA stable version.
so it did not come up to my mind that i ll need this on the "downstream" router.

if i understood this right, i would then need to add option prefix for that br-lan/64 into my wan/64 section into config, right?

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