Hi!
In our students' hostel we have 6 DSL lines (dialups to different
providers); we have set up a linux box (currently running 2.6.11-rc2-mm2,
but the problem described hereafter also applies to previous 2.6-series
kernels) with help from
http://lartc.org/howto/lartc.rpdb.multiple-links.html#AEN298
Our Setup looks like this:
10.0.0.0/8 10.70.255.1
+----------+ +-----------+
| intranet |---| linux-box |
+----------+ +-----------+ 10.254.0.1
| | | +-----------+
| | +-----| HW-router |---(DSL -> Provider)
| | +-----------+
| |
| +--------- (see above) [10.254.0.2]
+------------- (see above) [10.254.0.3]
(Above schematics drawn with only 3 instead of 6 DSL links)
Our problem is as follows: it seems that when the route cache expires also
existing TCP connections are rerouted, causing the connection to get lost.
(Just a theory - I don't know how to check that)
While that is fully comprehensible with UDP traffic, I thought I read
somewhere that this shouldn't apply to TCP traffic (connections - once
established - will always be routed through the initial hop).
Does anyone know how to avoid this problem (which makes downloading big
files a pain as some download-manager has to be used that supports
appending/byte ranges)? Am I doing something wrong here, did I forget
something?
Our Setup is as simple as setting a multihop default route on the linux
box like this:
ip route add default proto static \
nexthop via 10.254.0.2 dev eth0 \
nexthop via 10.254.0.3 dev eth0 \
nexthop via 10.254.0.1 dev eth0 \
nexthop via 10.254.0.4 dev eth0 \
nexthop via 10.254.0.5 dev eth0
We don't do any NAT as this is done by the hardware DSL routers.
Thank you for any help!
Marcus
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