GNS3 and VRRP Timers

While testing out a VRRP solution, I noticed that it was not performing as expected. The VRRP address was unresponsive so I started to investigate. Turning on console logging, I saw a large amount of flapping between Backup and Master states.

...
*Mar  1 02:37:23.739: VRRP: Grp 1 Event - Master down timer expired
*Mar  1 02:37:23.739: %VRRP-6-STATECHANGE: Vl20 Grp 1 state Backup -> Master
*Mar  1 02:37:25.095: %VRRP-6-STATECHANGE: Vl20 Grp 1 state Master -> Backup
...

It turns out that running 8 routers in GNS3 on my laptop was slightly under-powered platform and resulting in over a 2 second maximum response time from a VRRP peer.

Sending 8000, 100-byte ICMP Echos to 10.10.20.1, timeout is 2 seconds:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!..!!!..........................
......................................................!!!!!!!!!!!!!!!!
!!....................................................................
.....................!!!......................!!!!!!!!!!!.!!!!!!!!!!!!
..!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!.!!!!!!!!!!.!!!!!!!!!!.!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.
Success rate is 74 percent (611/818), round-trip min/avg/max = 4/705/1996 ms
Server-A#

After adjusting the advertise timers, everything started to perform as expected.

R1#
interface Vlan20
 ip address 10.10.20.2 255.255.255.0
 vrrp 1 ip 10.10.20.1
 vrrp 1 timers advertise 10
 vrrp 1 priority 110
 
R2#
interface Vlan20
 ip address 10.10.20.3 255.255.255.0
 vrrp 1 ip 10.10.20.1
 vrrp 1 timers advertise 10

 

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