GLBP PROTOCOL - BALANCING PROBLEM

[ROGER FERNANDO MAJO ZACARIAS]

Hello,

We have configured GLBP in two routers: 2801 and 3825.

The ip address of the routers are:

2801: 10.10.10.1 / 24

3825: 10.10.10.2 /  24

We have configured the GLBP so 2801 be the active and the 3825 the stanby but when we checked the paquets routing all the traffic is forwarder through 3825. What we want is that 2801 be the active and if the wan connecticon fails in 2801 the 3825 assume the rol of active.

We are attaching a file with the GLBP negotiation between routers.

Can you tell me what i need to configure in GLBP so traffic be routed trough 2801 and at the same time the link to 3825 be active.

What be want is to keep both routers active so traffic but traffic must be routed trough 2801 and if the wan link associated to 2801 is down the 3825 assume all traffic. 3825 must be active at the same time because we are using this router to send some kind of traffic.

Thanking any answer.

[Mohamed Sobair · Accepted solution]

Hi,

GLBP introduce the concepts of two things:

1- The Active Virtual Gateway.

2- The Active Virtual Forwarder.

Now, when GLBP configured on two routers or more, all router are Active virtual forwarders , and Only one router is the Actual Active virtual Gateway , meaning the AVG is responsiple for Replying to ARP requests send by the local hosts.

Now, if you want 2801 to be the "AVG", then simply specify higher priority in the GLBP (Default is 100) , however this doesnt mean the 3825 wont be forwaring traffic , as I said both routers will be used to forward traffic at the same time not like for example HSRP, however ONLY one router is responsible for replying to ARP requests.

I hope this helps,

Regards,

Mohamed

[Giuseppe Larosa · Accepted solution]

Hello Roger,

use HSRP or VRRP if you want only one router to forward traffic out of the client Vlan, GLBP is designed to perform forms of load balancing having the AVG to answer to ARP requests of different clients using different AVF MAC addresses.

if you test GLBP with a single client you can get:

>> when we checked the paquets routing all the traffic is forwarder through 3825

once the client has an ARP entry for default gateway it uses it so tests with a single client can provide results like the above

Hope to help

Giuseppe