How to bridge different ISP

oasis16 · 03-30-2011, 01:02 AM

Dear all,

i have two ISP, and i want to bridge each IP. Here my example;

ISP one : 10.10.10.1/29
ISP two : 172.16.100.1/28

my network design,

ISP one -- Bridge -- ISP two
##########|
########Switch
##########|
#######USER / Server
(with different IP for each server,
from different ISP)

the example bridge with single ISP;

Code:

brctl addbr br0
brctl addif br0 eth0
brctl addif br0 eth1
#adding ip for eth0 and eth1
ifconfig eth0 0.0.0.0
ifconfig eth1 0.0.0.0
ifconfig eth0 promisc up
ifconfig eth1 promisc up
brctl sethello br0 1
brctl setmaxage br0 4
brctl setfd br0 4
#adding ip to bridge interface (br0)
ifconfig br0 10.10.10.120 up
#adding internet gateway
route add default gw 10.10.xxx.xxx

can we setup for two ISP with different gateway ??

xaminmo · 04-18-2011, 11:40 AM

If you bridge, then your gateway doesn't matter. Each user needs two IPs and two gateways. Windows users won't really load balance between the routes.

With two ISPs it's better to use a router appliance that will manage to ISPs for you.

If you really want Linux to do this, then how you proceed depends on where your IPs came from.

If you have IPs from IANA, then you could use BGP and broadcast on your own ASN through both ISPs. This is how the bigger networks do it.

If you do NOT have IPs from IANA, then you must set up dual-homed NAT on the Linux box. Then, set up something to load balance your outbound traffic. This can be static routes; equal metric static routes for 0.0.0.0; or a routing protocol such as OSPF with areas defined.