how to have two gateway?

golden_boy615 · 01-31-2009, 10:56 AM

hello every body.
I wanted to know how can I have two diffrent gate way.
I have a linux that have two connection to internet 1.ethernet 2.ppp
i do not want to send my packets at same time from them but i want both of them up that if when one of them going down my machine use another one as the gateway. i added both of them as default gateway with diffrent metrics but when i unploged my ethernet cable my ping did not goes through and stoped and when i ploged it back it start to pinging out side again.
what can I do for it.

baldy3105 · 01-31-2009, 12:33 PM

VRRP is what you want. You give your two gateways a real physical address each, then a third address acts as a shared virtual address, and its this you use as your default gateway on your hosts. If you have Cisco routers they also have a similar proprietary mechanism called HSRP which has a few more bells and whistles.

I seem to recall setting up VRRP on linux some time in the past, I don't think it was too hard. Google "vrrp linux howto" and I'm sure you'll find something.

golden_boy615 · 02-01-2009, 06:54 AM

thank you for your help but I can not use VRRP because my linux is a embedded linux on a embedded computer that can route and have IPtable and i have not any router in my way to confige . is there any solution with routing or iptable that I can use?

baldy3105 · 02-01-2009, 02:40 PM

Not that I am aware of. The problem is that of a mechanism that allows the host to know when the primary path has failed and causes it to re-ARP for a new gateway MAC address. You might try a script that pings the primary routers WAN link and changes the default route if it goes away.