Try using the -I option for ping, this forces it to use a certain interface:
ping -I ${MY_IP_1} -c 1 ${GATEWAY_1}
You can also add a route to the gateway to force it to use that interface. I
do the same for the 2 SMTP servers of the different ISP's. I can't connect
to one SMTP server from the other ISP anyway, so better make it impossible
altogether.
sufcrusher
----- Original Message -----
From: "Ming-Ching Tiew" <mingching.tiew@xxxxxxxxxxx>
To: <lartc@xxxxxxxxxxxxxxx>
Sent: Thursday, March 11, 2004 3:29 AM
Subject: script to perform dead gateway detection
>
> I am also having some difficulty in doing dead gateway
> detection using a shell script :-
>
> Basically I am using ping -c 1 ${GATEWAY_1} If it times
> out, I supposed it got into error, so it is probably time for me to
> change route.
>
> However, even if the ping comes back, it does not mean the
> GATEWAY is alive as my nexthop; this is because I figured
> that the packet could have made a U-turn via the one of the alive
> links to come back to answer the ping request, ie the gateway
> is alive for a packet on the external network, but the gateway
> is still down from inside point of view, and this can happen
> due to a faulty connection between by second link IP and the
> second link gateway !
>
> Without patching the kernel to do dead gateway detection,
> how do I find out if a particular gateway is dead as my
> NEXTHOP ?
>
>
>
>
>
>
>
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