HSRP (Hot Standby Router Protocol) Explained


Nowadays, it is very important to keep your network alive all the time. To not to face with that boring scenarios it is mandotary to set up a network which is redundant. Here we have some protocols to make our network redundant, they are HSRP, VRRP and GLBP. First we will talk about HSRP – Hot Standby Router Protocol.



HSRP is a protocol which provides redundancy and it is a Cisco proprietary protocol. HSRP’s hello timer is 3, hold timer is 10 seconds. You can see an HSRP topology overview above. ( Virtual MAC is established automatically as soon as standby group is selected)

Gateways are set up to standby groups on clients.

One of the gateways is active, other one is standby. ( That means there is no load balancing )

Virtual Router IP and MAC adress is created

There you can see an HSRP virtual MAC address : 0000.0C07.ACXX

  • 0000 is Cisco Vendor ID
  • 0C07 is HSRP ID
  • ACXX is standby group number.


SWITCH_A(conf)#interface VLAN 70
SWITCH_A(conf-if)#standby 1 ip
SWITCH_A(conf-if)#standby 1 priority 150


Trick :  Default priority value is 100, by this configuration we are making switch A default gateway. If you try to telnet from a server , you connect to switch A.

SWITCH_C(conf)#interface VLAN 70
SWITCH_C(conf-if)#standby 1 ip

Configuration is verified by :

SWITCH_A#show standby

If you just make this configurations and if Switch A is down, traffic goes ahead from Switch C. But after a while, if Switch A joins the network again, traffic still goes from Switch C. To prevent this we need to use “preempt” command on Switch A.

SWITCH_A#standby 1 preempt


There you can see another HSRP example above. Fastethernet 0/23 is connected to the Local Area Network.  If we make those configurations below :

SWITCH_A(conf)#interface VLAN 70
SWITCH_A(conf-if)#standby 1 track Fa0/23 60

That configuration means we are tracking f0/23. Priority in here is found by “priority – 60 , 150 -60 = 90 , as you can mention is less then default priority value of 100. Actually this config means if fa0/23 is down, make the priority 90 so that traffic will go ahead from other switch.

*** Hello and dead timers of HSRP can be configured manually too. This may tire the proccessor and should be used carefully.

#standby 1 timers msec 150 msec 700

Leave a Reply

Your email address will not be published. Required fields are marked *