[clug] A Routing problem

[Stephen Hodgman]

Thanks for the assistance.  I figured it would be possible somehow.  I 
can now apply that to my end of the system.
I need to find out if the "ip" command applies to the solaris box at the 
other end of the link.
Thanks again for the help.

Rod Tunks wrote:

> Yup,
> thats no problem.  You setup different routing tables based on source 
> address/device. This way each interface can see a completely different 
> set of routes.  We have a router here with 6 ethernet interfaces of 
> which 2 are feeds out of the building used for different purposes.
>
> Routing is done based on both source and dest addresses.
>
> Here's a quick cut and paste example :-
>
> # specify anything from 192.168.76.0/24 uses the new table called 
> privateip
> ip rule add from 192.168.76.0/24 table privateip
>
> #Set up the routes for this table.
> ip route add default via 192.168.99.1 dev eth5 table privateip
> ip route add 192.168.76.0/26 dev eth4 src 192.168.76.1 table privateip
> ip route add 192.168.76.208/28 via 192.168.0.2 dev eth2 table privateip
> ip route add 192.168.76.192/28 dev eth3 src 192.168.76.193 table 
> privateip
> <snip> and so on.
>
> You need to create the new table entry (ie 501) and optionally give it 
> a name for each routing table you need. In your case three tables may 
> be overkill but it gives you the most flexability if your networks are 
> perpetually in a state of flux (like ours)
>
> We had some issues with arp due to our rather weird lan setup and 
> found  echo 1 > /proc/sys/net/ipv4/conf/all/arp_filter was needed as 
> well. YMMV
>
> Very low end hardware will cope with this kind of set up no problems 
> at all. Our 6 port box is a PIII with 4 x 100M lans and 2 x 2M+ feeds 
> out of the building and doesnt raise a sweat. Gotta love linux routers!
>
> The linux advanced routing & traffic control howto covers this quite 
> well.
>
> Cheers
> -Rod
> (from next door)
>
> -----------------------------------------------------
> This email may contain traces of nuts and/or caffeine
>
>
> Stephen Hodgman wrote:
>
>> I have a question regarding routing.  I have a linux system with 
>> three interfaces say eth0, eth1 & eth2
>>
>> On eth0 is network 123.123.123.0/24 (say)
>> I want traffic entering eth1, destined for 123.123.123.0/24 to be 
>> routed to eth0 - always
>> I want traffic entering from eth2 destined for 123.123.123.0/24 to be 
>> routed to eth2 - always
>> The reason is that there is a route either way but I only want one 
>> device to route directly.
>>
>> Can this be done?  It seems to require routing tables based on source 
>> address/interface.
>> I would appreciate knowing how this can be done.
>> TIA.
>>

-- 
Steve Hodgman
Ph: +61 2 6285 3460
Fax: +61 2 6285 3459
Mobile:	+61 407 182 355
steve at namsys.com.au
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