VRRP operations possibly affected by spanning-tree protocol?

Hi Group,

 

I have the following VRRP scenario:

 

L3 Switch_1 <-----------------> VRRP Router: RTR_1

        |

        |

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L3 Switch_2 <-----------------> VRRP Router: RTR_2

 

VRRP Routers RTR_1 and RTR_2 are connected through two L3 switches, each using a 100Mbps, full duplex link. The two L3 switches are inter-connected using a 1Gig full-duplex link. The VRRP advertisement interval = 1sec.

 

While testing VRRP operations, the following behaviour was observed:

1) RTR_1 is the primary address owner and hence, the master VRRP router. RTR_2 is the backup VRRP router. This is a steady state function.

 

2) By disconnecting the cable between RTR_1 and L3 Switch_1, a VRRP transition is forced. RTR_2 becomes the master VRRP router in little over 3 seconds. RTR_1 is in "init" state.

 

3) When connectivity between RTR_1 and L3 Switch_1 is restored, RTR_1 becomes the master (primary address owner). However, it takes 45-50 seconds for RTR_2 to receive the first VRRP advertisement from RTR_1. As soon as RTR_2 receives the first VRRP advertisement from RTR_1, it sends its last VRRP advertisement with priority = 0, withdrawing from the role of master router.

 

The gap of 45-50 seconds is undesirable. It should have been immediate, because preemption is allowed.

 

I suspect that this condition could be caused if spanning-tree is enabled on ports of the both of L3 switches connected to RTR_1 and RTR_2. Note, that ports of RTR_1 and RTR_2 does not participate in spanning-tree and does not send any BPDU.

 

Has anyone encountered this situation earlier? Please share your opinions.


Thanking you, 
Suketu Soni
 



 		 	   		  
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