Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Community Member

HSRP - Is the active router monitoring the standby router?

Hello,

I have a question regarding HSRP. I have a strange connection problem involving 2 1841 router as WAN router and 2 non-Cisco Layer 3 switches as LAN router. For yet unknown reasons the standby router transitions into the speaking and activ state. I can see log messages on the standby router indicating that.

Should I be able to see log message on the primary router indicating that standby router is doing something.

Does the active router keep track of the hello packets from the standby router and will create some log message if these packets are missing?

dirk

1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Blue

Re: HSRP - Is the active router monitoring the standby router?

dirkfeldhaus wrote:

Hello,

I have a question regarding HSRP. I have a strange connection problem involving 2 1841 router as WAN router and 2 non-Cisco Layer 3 switches as LAN router. For yet unknown reasons the standby router transitions into the speaking and activ state. I can see log messages on the standby router indicating that.

Should I be able to see log message on the primary router indicating that standby router is doing something.

Does the active router keep track of the hello packets from the standby router and will create some log message if these packets are missing?

dirk

Dirk

Just did a quick test with GNS3 using 2 3745 routers. I had logging at debug level. The active router does indeed keep track of the standby router because as already explained the 2 routers exchange HSRP multicast packets between them. However i could not get the active router to log a change in the standby state even with debugging on.

I guess if you needed this you could look at using something like EEM.

Jon

8 REPLIES
Hall of Fame Super Bronze

Re: HSRP - Is the active router monitoring the standby router?

Hello packets are not unicast to each other. They are sent to a multicast group (224.0.0.2). If the standby router does not

receive a hello packet without a period of time, it will transition to active. It seems the current active loses its ability to send/respond hello

packets to that group. Verify Layer1 connectivity along with any filtering to the multicast group.

Regards

Edison

Re: HSRP - Is the active router monitoring the standby router?

Hello,

I have a question regarding HSRP. I have a strange connection problem involving 2 1841 router as WAN router and 2 non-Cisco Layer 3 switches as LAN router. For yet unknown reasons the standby router transitions into the speaking and activ state. I can see log messages on the standby router indicating that.

Should I be able to see log message on the primary router indicating that standby router is doing something.

Does the active router keep track of the hello packets from the standby router and will create some log message if these packets are missing?

dirk

Hi Drik,

If stanby router is getting transition into active state. The error messages signify the loss of HSRP hellos between the peers.A random, momentary loss of data communication between the peers is the most common problem that results in these messages. HSRP state changes are often due to High CPU Utilization. If the error message is due to high CPU utilization, put a sniffer on the network and the trace the system that causes the high CPU utilization.

There are several possible causes for the loss of HSRP packets between the peers. The most common problems are physical layer problems.

Hope to Help !!

Ganesh.H

Community Member

Re: HSRP - Is the active router monitoring the standby router?

Thanks for your help guys, but I was looking for something different :-)

A "show standby brief" on primary router will show if there  is a known standby router or if the standby router is unknown. That means that the primary router is keeping track of it's standby router.

I'm wondering if the active router logs a message if a couple of  Hello packets from the standby router are missing.

As this is already the primary router is doesn't really need to do anything, this information would be purely informational.

Re: HSRP - Is the active router monitoring the standby router?

Thanks for your help guys, but I was looking for something different :-)

A "show standby brief" on primary router will show if there  is a known standby router or if the standby router is unknown. That means that the primary router is keeping track of it's standby router.

I'm wondering if the active router logs a message if a couple of  Hello packets from the standby router are missing.

As this is already the primary router is doesn't really need to do anything, this information would be purely informational.


Hi,

A show standby brief command tell you the status of the active and standby router state in the hsrp group and if the hello packet is getting missed between the two hsrp peers then both will assume to be active for the hsrp group,This will end in network problem.

Hope to Help !!

Ganesh.H

Remember to rate the helpful post

Hall of Fame Super Blue

Re: HSRP - Is the active router monitoring the standby router?

dirkfeldhaus wrote:

Hello,

I have a question regarding HSRP. I have a strange connection problem involving 2 1841 router as WAN router and 2 non-Cisco Layer 3 switches as LAN router. For yet unknown reasons the standby router transitions into the speaking and activ state. I can see log messages on the standby router indicating that.

Should I be able to see log message on the primary router indicating that standby router is doing something.

Does the active router keep track of the hello packets from the standby router and will create some log message if these packets are missing?

dirk

Dirk

Just did a quick test with GNS3 using 2 3745 routers. I had logging at debug level. The active router does indeed keep track of the standby router because as already explained the 2 routers exchange HSRP multicast packets between them. However i could not get the active router to log a change in the standby state even with debugging on.

I guess if you needed this you could look at using something like EEM.

Jon

Community Member

Re: HSRP - Is the active router monitoring the standby router?

Hi Jon,

thanks for your reply and the work you spent on that. That was really helpful.

I appreciate it.

dirk

Hall of Fame Super Blue

Re: HSRP - Is the active router monitoring the standby router?

dirkfeldhaus wrote:

Hi Jon,

thanks for your reply and the work you spent on that. That was really helpful.

I appreciate it.

dirk

Dirk

No problem, glad to help and thanks for the rating.

It is worth noting that i tested with 3745 routers as i say running 12.4 so HSRP logging behaviour may differ between IOS version and routers/L3 switches but it seems you are seeing the same thing with your devices.

Jon

Community Member

Re: HSRP - Is the active router monitoring the standby router?

That's right. I saw the logs from 2 1841 router. that's what get me thinking.Then I tested with 2 3560 L3 switches. Both running 12.4 images.

1019
Views
0
Helpful
8
Replies
CreatePlease to create content