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HSRP virtual being used?

Collin Clark
VIP Alumni
VIP Alumni

I have two routers and have HSRP running between the fast ethernet interfaces. Actually there are two groups running. RTR_A real IP is .1 and it is Active for .3 (group 1). RTR_B real IP is .2 and it is Active for the .4 address (group 2). I want to remove one of the groups. Anyone know how I can see if the .4 virtual is being used as a default gateway by a client?

20 Replies 20

cisco_lad2004
Level 5
Level 5

I would use a sniffer if I expect to see heavy load of ARP request.

"debug arp" would also help...but I simply would not dare :-)

Sam

These are on our internet routers, so no debug of course. Sniffer might be OK, but I was hoping for some magical command I didn't know.

I just did a debug on arp in the lab and it shows physical interfaces, not virtuals :-(

I got both IP and MAC, perhaps we have different setup and configs.

*Mar 18 11:25:43.803: IP ARP: sent req src 10.1.1.1 cc01.12f4.0010,

dst 10.1.1.2 cc02.12f4.0010 FastEthernet1/0

I did too, but it shows the physical interface instead of the virtual interface.

rakesh.hegde
Level 1
Level 1

Hi Collin,

You may wan to use mac address input accounting on Router B to get all MACs that sent frames to the interface.

int <>

ip accounting mac-address input

sh int <> mac-accounting

-Rakesh

Rakesh,

Thanks for the pointer. I'll lab it up and see if it gives me the info I need.

Rakesh,

We're getting closer. I enabled accounting, sent some traffic, but the command show interface VLAN1 mac-acc shows the source MACs destined for the VLAN1 interface. That's works, but I may have clients pointing directly to the physical interface. Thanks for the command.

No problem :-)

-Rakesh

Edison Ortiz
Hall of Fame
Hall of Fame

How can you determine that? A Client would have this information statically or dynamically within its TCP/IP information so what's to say this client hasn't be used for 2 weeks because the user was on vacation?

I'm afraid this request is not possible to accomplish without some leg work or having some technical support calls.

__

Edison.

Hi Edison,

The command can be used to get a fair idea of the number of MACs sending traffic to router's interface. If we have just 2 routers and hosts, and if group 2 is active on Router B and no client is using .4, you shouldn't see any traffic right ?

It may or may not help depending on what else is going on in the LAN.

-Rakesh

Rakesh,

Sorry for any confusion but I didn't reply to you but to Collin. I suggest to view these posts in a threaded format.

___

Edison.

Hi Edison,

No problem, point taken :-)

-Rakesh.

PUBLIC NETWORK. There are no clients that haven't been used for two weeks. Please read and understand before posting.

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