Secondary glbp router in listenm instead of active

[emurray]

I have glbp configure with load-balancing host-dependent. But the secondary does not become an active forwarder. I have tried many changes with no luck. Here is my config on the Primary

glbp 10 ip x.x.x.x
 glbp 10 priority 120
 glbp 10 preempt
 glbp 10 weighting 100 lower 91
 glbp 10 load-balancing host-dependent
 glbp 10 weighting track 1 decrement 100
 glbp 10 weighting track 2 decrement 100
 glbp 10 weighting track 3 decrement 100
 glbp 10 forwarder preempt delay minimum 1

The configuration of the Secondary

glbp 10 ip x.x.x.x
 glbp 10 priority 110
 glbp 10 preempt
 glbp 10 load-balancing host-dependent

Any advice is welcome

[Jens Albrecht]

Hello @emurray,

the GLBP configuration looks good and when I paste it into my lab I get the expected result:

rtr1#
*May 23 15:11:14.299: %GLBP-6-STATECHANGE: GigabitEthernet0/0 Grp 10 state Speak -> Active
*May 23 15:11:24.751: %GLBP-6-FWDSTATECHANGE: GigabitEthernet0/0 Grp 10 Fwd 1 state Listen -> Active
rtr1#

rtr2#
*May 23 15:11:42.157: %GLBP-6-FWDSTATECHANGE: GigabitEthernet0/0 Grp 10 Fwd 2 state Listen -> Active
rtr2#

It is important to note that Rtr1 is active as forwarder 1 and Rtr2 is active as forwarder 2.
The roles get a bit more clear when looking at the output of the "show glbp" command on Rtr1:

On Rtr2 the states for forwarders 1 and 2 are switched but the important point is that both routers see each other as group members.

If this is not the case on your setup, then the first thing to check is connectivity. Can the routers ping each other successfully and is the glbp IP address the same on both sides.

In case things still do not work, then please provide more detailed configs, the topology of your setup and the output of the "show glbp" command on both sides.

HTH!

[emurray]

I saw that but what confused me was the fact that it says: There are two forwarder (1 active). I was expecting to see two forwarder active on that sentence.

Also I see the forwarder 2 in a listen state and that makes me think it is not in a forwarding state.

[Jens Albrecht]

Only one router can be active as Forwarder 1 and only one router can be active as Forwarder 2 at any given time.

Why? Because for each forwarder there is a virtual MAC address assigned and this virtual MAC address can be active only on one router. The virtual MAC addresses and each owner can be seen with the "show glpb" command as well:

MAC addresses must be unique within a given subnet so only one router can actively use it. So each forwarder uses its own virtual MAC address and only one router can be active as a given Forwarder <num>.

Only if you shutdown Router 2, then Router 1 will become active as Forwarder 2 as well to provide redundancy.

You can also check this on the clients. Look at the ARP cache of the clients and you will notice that some map the virtual IP to the MAC address of Forwarder 1 while others map it to the MAC address of Forwarder 2. You can also use a traceroute from the clients to verify that load-balancing works across both routers.

HTH!