HSPR is one of the FHRP (First Hop Redundancy Protocols) Protocols
This Protocol deals with gateway redundancy.
What is Gateway Redundancy ?
Consider the above, Example, If the PC wants to communicate to the internet it needs to send traffic via either one of the 3 routers(R1 , R2 or R3 ). But, you can configure only one gateway in PC. All the traffic from PC will be forwarded to the gateway. If the gateway IP belongs to Router R1, and the R1 goes down, then can't able to access the Internet, If we need to access, we need to change the gateway in PC.
HSRP can solve this issue by creating a Virtual IP Address on the routers, so that we can configure the Virtual IP Address as the gateway in PC and avoid manual assigning of gateway every-time when the traffic moving router goes down.
Configuration :
#configure terminal
(config)#interface fastEthernet 0/0
(config-if)standby 1 ip 192.168.1.254
(config-if)standby 1 priority 200
HSRP States :
Initial | This is the first state when HSRP starts. You'll see this just after you configured HSRP or when the interface just got enabled |
Listen | The router knows the virtual IP address and will listen for hello messages from other HSRP routers. |
Speak | The router will send hello messages and will join the election to see which router will become active or standby. |
Standby | The router didn't become the active router but will keep sending hello messages. If the active router fails it will take over. |
Active | The router will actively forward packets from clients and sends hello messages. |
How it works ?
The Active will send hello messages to the routers that are in standby mode. Routers in standby mode will listen to the hello messages, if they don't receive anything from the active router they will wait for the hold time to expire before taking over. The hold time is 10 seconds by default, and hello timer is 3 sec by default.
By default the switch with the highest priority will become the active HSRP device. If the priority is the same then the highest IP address will be the tie-breaker. (Default Priority value is 100 )
HSRP versions:
HSRPv1 | HSRPv2 | |
Group numbers | 0-255 | 0-4095 |
Virtual Mac-Address | 0000.0c07.acXX (XX = group number) | 0000.0c9f.fxxx (XXX = group number) |
Multicast address | 224.0.0.2 | 224.0.0.102 |
You can also look into the video Tutorial in Tamil :
That's it
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