I am not sure if this problem has already being
posted, but I haven't found any solution. Excuse me if
it's a repost but would appreciate any pointers. I have newly configured Multipath default route. I
have 1 local connection and 4 internet connections. I
am using kernel 2.6.7 and have applied Julian's
relevent patches. When the next hop is down, julian's patch takes care
of the links changing the route to only the links
which it finds are up and forwarding traffic to those
links. But if the problem is anywhere in between,
beyond the next hop, the links are not marked
identified as down (I down see the change in multipath
default route) and requests still go via them and
hence no connectivity, even if some other links are
up.
Does Julian's patch takes care of route only if next
hop is down. Any solution to this problem?
You are looking at the wrong layer. If the next hop is unreachable, which is a layer 2 thing, the system notices this and acts accordingly. If however a link further away is down, there is no such mechanism on layer 2 and your system cannot react to it (with standard means).
This is quite "psychic" if you want. Why should your system magically know there is a problem 4 hops upstream ? It only sees the links it is directly attached. The packets are accepted on one link and this is where the responsibility of your multihomed system ends. It neither does nor should track packets over the full path from source to destination.
There is a solution however: For that kind of thing you need to look into routing software (BGP, OSPF) which has this capability. If you don't control the upstream machines, you will need to get a bgp-peering with your upstream provider to be able to react to outages. If your mentioned 4 connections are standard home-adsl/cable connections, this might be difficult however.
Hope that helps. --
C U
- -- ---- ----- -----/\/ René Gallati \/\---- ----- --- -- -
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