Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements
Webcast-Catalyst9k
New Member

HSRP

How is looping avoided when using the same virtual MAC between two routers?

5 REPLIES
New Member

Re: HSRP

Not sure what you totally mean by "looping", but with HSRP only one of the HSRP routers is actually responding to the virtual mac address at a given time. The routers communicate to eachother who that primary router is. If the primary should fail, the other routers are no longer getting responses to keep alives, and they will elect a new primary.

In addition to this, other functions cease to exist such as when a router is in HSRP. For example with some versions of HSRP, icmp redirects are disabled. With newer versions this is not the case, you can get icmp redirects to function.

In short, there is communication going between routers in the HSRP group, and so only one is taking on the role of the primary router at a time.

Brian

New Member

Re: HSRP

Yes, Yes, But what I was concerned with were the switches. Do they get choked up by this?

New Member

Re: HSRP

The virtual MAC address is only bound to the primary router.

yunfeng.fan

New Member

Re: HSRP

When the primary fails, does the backup router take on the same address? If so is a loop is created.

New Member

Re: HSRP

When i used two cisco 25xx's in my labs, router .x and router .y are primary and secondary for .1. The virtual mac for .1 was going for router .x. But when i pull the cable out of router .x, the mac for .1 is the mac for router .y ethernet interface. The switch makes the adjustment according to the new ARP, i believe.

146
Views
0
Helpful
5
Replies
CreatePlease to create content