HSRP problem

[sameh.bushnaq]

I have HSRP running fine between two 3725 routers and I only want a way to make the ethernet interface down when the serial interface is down.So that a core swich ,which these two ethernet interfaces are connected to,will route certain traffic to another distination when both links are down.I heard that there is a new version of osi which can do that,if this is true what are these versions?

[amit-singh]

Didnt understand your question exactly. You have 2 routers with 2 serial interfaces each or 1 interfaces each. Is there any other router Via which you want to route the packts ? or what you want is when you serial interface goes down the packets showuld routed via another router.. Please give us more clear idea ??

regards,

-amit singh

[sameh.bushnaq]

Thanks for your reply.My situation is as follows,I have a core switch which is connected to three routers,two of them are running HSRP.I want when the serial links on these two routers go down,the ethernet interfaces also go down,so that the core switch will route the whole traffic to the third router.

[imnilesh]

Hi, as u explain above. u already configured HSRP on two router. and any one serial link goes down then definatley HSRP will take care to route the traffic with another router which configure with HSRP. so is there any reason to route traffice from third router.

//nil

[sameh.bushnaq]

Thanks.Actually I supposed the worst senario that both serials will go down at the same time so I want the core switch to notice that their ethernets are down to route to the third one.This is a DR site and I have to put all senarios.

[imnilesh]

ok, as said by u its L3 switch where all 3 rtr connected. can you configure secondary gateway in L3 of third rtr ethernet add.....

[amit-singh]

Hi,

Well, you have a complete redundent scenario and as pointed out by Nilesh you already have a fault tolerant n/w.

Which core switch do you have ? If you want you can use floating static routes or a default route pointing to 3rd router.

What's opinon Nilesh ?

regards

-amit singh

[sameh.bushnaq]

Hi,

I have Catalyst 3750,I already use a defalt route that pointing to another router which is connected to international link.but what is floating static route?and how it could help me?

[amit-singh]

Hi,

A floating static route is a route with more AD. A static route has an AD of 1.Normally a floating static route is used for redundency.For example If you have to different links and you want to use the static route redundecny for a given destination you can use it like :

ip route x.x.x.x y.y.y.y z.z.z.z

ip route x.x.x.x y.y.y.y w.w.w.w 20

where x is the destination network

y is the destination mask

z is the next gateway address and 20 is the AD value which makes it floating and will be used if first route doesnot work.

You can use a floating default route pointing to third router with a higher AD.

HTH

-amit singh

[sameh.bushnaq]

Thanks.But the problem in this case that both routes will pointing to ethernet interface which will stay up in case that the serial is down,so the switch will never know that the serial is down.the only solution I think is to force the ethernet to become down when the serial is down, which I hope to do it by the HSRP.

[amit-singh]

See,

in case of HSRP, if you enable interface tracking, router knows how to handle the traffic when the interface which was tracked has gone down. But in the third router scenario yes, we have to do a manual shiftover.

At this point of time I dont have any other suggestion in my mind. Let me think more of any other possiblity. Sorry :-)

HTH,

-amit singh

[jroyster]

Doesn't this sound like the job of a routing protocol?

HSRP's main function is for gateway protection for hosts. I believe you're asking for path selection which is what a routing protocol is for.

[sameh.bushnaq]

My friend,

I know that but my question is there anyway to bring the ethernet of a router ,that is running HSRP, down when the serial became down or not? I heard that there is HSRP version that can do that.