HSRP and GLBP

[Mohammed El-Negily]

What is the difference between HSRP and GLBP ?

[Sajid Ali]

GLBP performs a similar, but not identical, function for the user as the Hot Standby Router Protocol (HSRP) and the Virtual Router Redundancy Protocol (VRRP). HSRP and VRRP protocols allow multiple routers to participate in a virtual router group configured with a virtual IP address. One member is elected to be the active router to forward packets sent to the virtual IP address for the group. The other routers in the group are redundant until the active router fails. 
GLBP provides load balancing over multiple routers (gateways) using a single virtual IP address and multiple virtual MAC addresses. Each participate in forwarding packets. 

[InayathUlla Sharieff · Accepted solution]

HSRP uses a Virtual IP address that is managed by a primary router with a standby ready to step in if need be.  With GLBP the IP address is load balanced across different MAC addresses.  So if someone arps for the Gateway MAC address the Active Virtual Gateway (AVG) responds with the MAC address of a Active Virtual Forwarder (AVF) that can forward the Packets.

Check out these links for more info:

HSRP:

http://www.cisco.com/en/US/tech/tk648/tk362/technologies_tech_note09186a0080094a91.shtml

GLBP:

http://www.cisco.com/en/US/docs/ios/12_2t/12_2t15/feature/guide/ft_glbp.html

HTH

Regards

Inayath

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

As the other posters have noted, the major feature of GLBP is you can have more than one active physical gateway forwarder (to load balance traffic).

GLBP offers several methods to load balance traffic across its forwarding gateways.

(GLBP also has some features not found in HSRP v1 but found in mHSRP and/or HSRP v2.)