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New Member

Problem with HSRP

I have three switches conected A-B-C, the switch A is connect to one router, and the switch C is connect to the other router.The two routers are configured for HSRP for this lan. When the links between A-B or B-C is down the two routers are active for HSRP, and it give me for the routing. How can I configure the HSRP for that one of the routers put is standby when the link is down??.

Best regards and thanks...

9 REPLIES

Re: Problem with HSRP

Hi

Put a connection from A-C.

Thanks

Mahmood

New Member

Re: Problem with HSRP

No is possible othe phisical connection between A-C....? Do you know other solution ?? Is possible configure track between the connection wan between the two routers....

Re: Problem with HSRP

Hi

Iam not sure wheter I have understood your question . Is that you want to have one router as primary and other one as secondry when any link goes down .

Considering your design , pls let me know if your switch A is isolated from B&C and is there any way for your router to communicate with the other router . If so , something is possible. And if your switch A is losing the connectivity with B , LAN is isolated and it has no other go rather than via the router attached to it.

If my understanding is wrong , pls let me know to discuss further on the same.

regards

vanesh k

New Member

Re: Problem with HSRP

The connection between switches is A-B-C, A in connected to B, and B to C, when this links are down I get the two routers active in HSRP, and one part in the lan isolated. In A I have one router and in C other router for HSRP in the lan. The two routers have one wan connection that connect them. How is possible resolve this routing problem.

Re: Problem with HSRP

Hi,

If the link A-B-C is the only way that two routers communicate, when link A-B or B-C goes down, both routers will not see the hello message from each other. After the holddown timer expires, the active router will still remain active, and the standby router will become active.Then we have two active routers. So, the traffics come form hosts on switch A will go through router on the same swith (let's call it router A);the traffics come form hosts on switch C will go through router on the same swith (let's call it router C);and traffics from hosts on switch B will go through router A if link B-C is down or go through router C if link A-B is down.

Hope this Help

SSLIN

New Member

Re: Problem with HSRP

SSLIN is correct. I would check the L3 connection between the two routers to ensure traffic is passing both ways (i.e. not a uni-directional link). I ran into a similiar problem with a bad SFP GBIC on a fiber connection between my 4506 core switches.

New Member

Re: Problem with HSRP

~~~~~~~~~~~~

I have three switches conected A-B-C, the switch A is connect to one router, and the switch C is connect to the other router.The two routers are configured for HSRP for this lan. When the links between A-B or B-C is down the two routers are active for HSRP, and it give me for the routing. How can I configure the HSRP for that one of the routers put is standby when the link is down??.

Best regards and thanks...

~~~~~~~~~~~~~~~~~~~~

But if you do it...

Let's take a look:

You have Router1 <-> SwitchA <-> SwitchB <-> SwitchC <-> Router2. Router1 is active, Router2 is standby. All peers see RouterA as active. Then link between (for example) SwitchB and SwitchC fails. If Router2 remain standby, then peers from SwitchC would see your HSRP address, right? Because link to Router1 fails for them and SwitchC.

To become active in that case HSRP was designed...

What for do you need RouterB to remain standby?

New Member

Re: Problem with HSRP

HSRP maintains the active router via multicast hello messages. If a standby router fails to hear hellos from the active router within the alloted time, it will become active. From the network description, no link exists between Router 1 and 2, so they are reliant on the switch connections to recieve the hello messages. Since the switches are daisy chained, one failed link results in the flow of hellos ceasing. The active router remains active, and the standby moves to the active state.

New Member

Re: Problem with HSRP

What you could do is utilize the track function similar to tracking an interface. Create a track group using echo reachibility for the other router and configure your HSRP group to track that track group.

Example:

Router B Config snip:

!

!

track 123 rtr 321

!

rtr 321

type echo protocol ipIcmpEcho 192.168.1.2 <-- IP of router A

request-data-size 100

timeout 2000

threshold 150

frequency 8

rtr schedule 1 start-time now life forever

!

!

int fa0/0

ip address 192.168.1.3 255.255.255.0

standby ip 192.168.1.1

standby track 123

What this does:

defines a rtr entry that uses an ICMP ping to the IP address. The track group executes the rtr entries at their set times (8 seconds in this case) and records pass or failure. The HSRP gets triggered into standby whenever there is a failure to reach the other peer.

This will cause one router to drop into standby. Don't use it on both at the same time, or neither router will become active in the event the link is severed. This will guarantee that Router A stays up if router B can't be reached.

I'm not sure where the WAN link comes into play, but if you expound on any issues, we can tackle them for you.

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