RE: [LARTC] Multipath route problem

["Greg Scott" <GregScott@InfraSupportEtc.com>]

> # ip route add default nexthop via 10.10.10.2 dev eth0 nexthop via
> 10.10.10.1 dev eth0

I wonder if this is a problem going out over the same NIC to the two 
providers?  All the docs I can find show each provider on its own NIC.  

I am setting up something similar and was just about to ask if I can 
do it with one NIC connecting all the providers.  That would save me 
a bunch of precious PCI slots!

In my case there are 4 - count 'em - 4 external routers to the 
Internet!  3 of them are supposed to load-balance for user traffic 
and the fourth is for a bunch of internal servers with known IP 
Addresses.  So there will be a fwmark policy that puts the routes 
for those servers into its own table.  

Life would be great if I could do all this on a single NIC connecting 
all of those routers.  Or do Neils and I both need a separate NIC for 
each router?

thanks

- Greg



-----Original Message-----
From: niels@wxn.nl [mailto:niels@wxn.nl]
Sent: Wednesday, July 31, 2002 8:42 AM
To: lartc@mailman.ds9a.nl
Subject: [LARTC] Multipath route problem


Hi ... I have 2 DSL lines all up and running on one RedHat box... 

I want to balance traffic going out over the two providers

The 2 DSL routers Have IP's 10.10.10.1 / 10.10.10.2 ... my linux box (eth0)
has IP 10.10.10.10 connected on a separate ethernet 

SO I read the http://lartc.org/howto/lartc.rpdb.multiple-links.html guide
(chapter 4.2.2)

In my case I have to make these routes

# ip route add default nexthop via 10.10.10.1 dev eth0 nexthop via
10.10.10.2 dev eth0

Works Fine!! every connection request going is perfectly balanced sent out
via both gateways
But works only on the linux box itself! from the (masqueraded) clients it
doesn't:

Every first  request which is masqueraded -> gateway 10.10.10.1 (works fine)
Every second request which is masqueraded -> gateway 10.10.10.2 (don't get
reply back)

When I change the multipath route so that 10.10.10.2 is the first hop

# ip route add default nexthop via 10.10.10.2 dev eth0 nexthop via
10.10.10.1 dev eth0

Gw 10.10.10.2 (fine) 
Gw 10.10.10.1 (doesn't work ... Only from the linux box itself)

So it every time seems to be the second "hop" in the multipath route which
isn't beeing masqueraded properly!

Can anyone help?

Thanks in advance! 
Niels!






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