01-19-2007 02:21 AM - edited 03-05-2019 01:52 PM
Hi All,
I have two catalyst 3560 switches with many SVIs configured on them. All the SVIs configured to use HSRP. Last time when I tried to add a new SVI with a new HSRP the switch ignored it and indicated that I reached the max 32 limit.
I looked at the cisco web and found the following link:
This tells that "HSRP can be configured on a maximum of 32 VLAN or routing interfaces."
I do not have more that 32 HSRPs on the switches so I don't understand why I couldn't add a new HSRP:
#sh standby | i Gro
Vlan1 - Group 1
Vlan10 - Group 10
Vlan12 - Group 12
Vlan20 - Group 20
Vlan21 - Group 20
Vlan22 - Group 20
Vlan23 - Group 20
Vlan25 - Group 25
Vlan26 - Group 20
Vlan27 - Group 20
Vlan28 - Group 20
Vlan29 - Group 20
Vlan30 - Group 30
Vlan31 - Group 20
Vlan40 - Group 40
Vlan41 - Group 41
Vlan42 - Group 41
Vlan43 - Group 43
Vlan44 - Group 40
Vlan45 - Group 45
Vlan46 - Group 40
Vlan47 - Group 47
Vlan48 - Group 48
Vlan50 - Group 50
Vlan70 - Group 70
The switches hear other HSRP hellos from other devices in VL12, however those HSRP groups are not configured on them. For example:
#sh standby all
...
Vlan12 - Group 13
State is Disabled
Virtual IP address is a.b.c.d (learnt)
Active virtual MAC address is 0000.0c07.ac0d
Local virtual MAC address is 0000.0c07.ac0d (v1 default)
Hello time 3 sec, hold time 10 sec
Preemption disabled
Active router is x.x.x.x, priority 120 (expires in 8.708 sec)
Standby router is x.x.x.x, priority 105 (expires in 8.532 sec)
Priority 100 (default 100)
...
Counting all the HSRP groups which are configured and learned by the switches I realized that I reached the 32 limit.
#sh standby all | i Group|State
Vlan1 - Group 1
State is Active
Vlan1 - Group 201
State is Disabled
Vlan10 - Group 10
State is Active
Vlan12 - Group 12
State is Active
Vlan12 - Group 13
State is Disabled
Vlan12 - Group 14
State is Disabled
Vlan12 - Group 15
State is Disabled
Vlan12 - Group 16
State is Disabled
Vlan20 - Group 20
State is Active
Vlan21 - Group 20
State is Active
Vlan22 - Group 20
State is Active
Vlan23 - Group 20
State is Active
Vlan25 - Group 25
State is Active
Vlan26 - Group 20
State is Active
Vlan27 - Group 20
State is Active
Vlan28 - Group 20
State is Active
Vlan29 - Group 20
State is Active
Vlan30 - Group 30
State is Active
Vlan31 - Group 20
State is Active
Vlan40 - Group 40
State is Active
Vlan41 - Group 41
State is Active
Vlan42 - Group 41
State is Active
Vlan43 - Group 43
State is Active
Vlan44 - Group 40
State is Active
Vlan45 - Group 45
State is Active
Vlan45 - Group 201
State is Disabled
Vlan46 - Group 40
State is Active
Vlan46 - Group 146
State is Disabled
Vlan47 - Group 47
State is Active
Vlan48 - Group 48
State is Active
Vlan48 - Group 100
State is Disabled
Vlan50 - Group 50
State is Active
Vlan50 - Group 150
State is Disabled
Vlan70 - Group 70
State is Active
Vlan70 - Group 170
State is Disabled
Is this a normal behaviour of the cat3560, to count those HSRP groups which are not configured on it?
Any thoughts.
Thanks
01-24-2019 03:58 PM - edited 01-25-2019 04:30 PM
It looks like you are seeing the expected behavior. The switches are not counting the unconfigured HSRP groups, the switches are counting the multiple interfaces that the groups are configured on.
So since you have other routers in the same network with interfaces in the same collision domain and in the same group as the affected router, you have reached your 32 group limit and cannot configure anymore HSRP instances.
If you configure the same HSRP group number on multiple interfaces, the switch counts each interface as one instance:
For example, if you configure HSRP group 0 on VLAN 1 and on port 1, the switch counts this as two instances.
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