#glbp

[pynet-labs]

Understanding FHRP (First Hop Redundancy Protocol) - PyNet Labs

FHRP stands for First Hop Redundancy Protocol which is designed to provide redundancy to the gateway router within the organization's networ

[ciscohite]

A most frequently asked question I hear from CCNA & CCNP students is - What are the most used technologies in the enterprise ? Well, there could be no perfect answer to this question but I am sharing the list of most commonly used technologies from my ten years of experience. Lets start with the discussion of the day -

[ciscohite]

Gateway Load Balancing Protocol (GLBP) as we all know is a Cisco's protocol to deal with the failure of the default gateways in the LAN but when compared with any other protocol of similar nature (HSRP, VRRP etc) it stands much ahead of all these protocols. GLBP is a feature rich protocol with superb ease of configuration.

[ipnet]

Redundancy Protocols - HSRP, VRRP and GLBP

 Issues with Redundancy Protocols

Technologies:

HSRP:

Hot Standby Router Protocol - Created by Cisco

VRRP:

Virtual Router Redundancy Protocol - Created by IETF - Standard work with multiple vendors

GLBP:

Created by Cisco

Issues:

1. Client using the wrong gateway ip address - ipconfig for pc and ifconfig for mac

2. Wrong device acting as the active device - sh standby brief - The device that we want to be active has to have a higher priority number.

3. Missmatch authentication - sh run [interface]

NOTE: Make sure that if a key-chain is on the interface, that the key-chain was created on the global config.

4. The Active device doesn't gain the Active after reboots - sh standby brief

5. Wrong group number - sh standby brief

Good Show command to know:

show standby brief - harp

show glbp brief - glbp

show vrrp brief - vrrp

show standby [interface] - hsrp

show glbp [interface] - glbp

show vrrp [interface] - vrrp

Debug standby terse - hsrp

Debug glbp terse - glbp

Debug vrrp event - vrrp

sh run interface [interface]

note: This is only redundancy protocol troubleshooting. You still need to know the other technologies to be able to fix any issues with redundancy protocol. Example, if layer 1 is not working HSRP, VRRP or GLBP are not going to work.