Re: [LARTC] Loadbalancing the gateway

["Jason A. Pattie" <pattieja@pcxperience.com>]

You might try multi-path routing.  It doesn't exactly load balance the 
lines, as in aggregating the bandwidth together, but it does allow N 
number of simultaneous connections (where N would be the maximum number 
of different routes you have).

In your scenario, let's say you have the 3 routers with IP addresses of 
1.1.1.1/30, 2.2.2.2/30, and 3.3.3.3/30.  Now, you have your Linux 
firewall/gateway/router/thingy between the routers and the client.  On 
your Linux box, you could have 3 separate network cards each connected 
to one of the routers, or you could have a single network card connected 
to all three routers via a hub or switch (switch would probably be 
better).  Let's say you have one network card.  In that scenario, you 
would assign an IP address in each of the network ranges for the each of 
the routers.  I.e., 1.1.1.2/30, 2.2.2.3/30, 3.3.3.4/30 (note: these IP 
address are probably completely incorrect for assignment in the network 
range I have chosen, just using them as examples; you would get usable 
IP's from your ISP).  To assign these IP address, use the 'ip' command.

ip addr add 1.1.1.2/30 brd + dev eth0
ip addr add 2.2.2.3/30 brd + dev eth0
ip addr add 3.3.3.4/30 brd + dev eth0

Now, you will need to setup the multi-path route as your default route. 
 You can specify the 'equalize' parameter if you like, but I have found 
that it doesn't do exactly what you might expect it to do.

ip route add default nexthop via 1.1.1.1 dev eth0 \
                     nexthop via 2.2.2.2 dev eth0 \
                     nexthop via 3.3.3.3 dev eth0

And that should take care of that.  Now all of this is assuming that you 
have multiple, different IP ranges for your 3 ISDN lines.  If they are 
all in the same network range, you can forego having 3 IP's assigned to 
the same network card on your firewall.  In that case you would only 
need one.  Then substitue appropriately for the router IP addresses.

Logu wrote:

>Hi,
>I have 3 isdn connections. Is it possible to loadbalace the bandwidth using
>a linux box in between the routers and the client. I will be very much
>greatful to you if someone helps me in this.
>
>-Logu
>
>
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-- 
Jason A. Pattie
pattieja@pcxperience.com




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