Hot Standby Route Protocol (HSRP) provides redundant connectivity for host devices in a Cisco network. It’s basically an automatic backup system. If the primary router loses connectivity, it will immediately failover to a backup router.
What is Hot Standby Router Protocol?
Hot Standby Router Protocol is a protocol that prioritizes a set of routers to be the primary and standby routers for a subnet of devices. If the primary router fails, protocol will automatically connect with the router with the next-highest priority. Redundancy is initiated from the router. This means that devices don’t have to be configured individually.
What are Standby Groups in HSRP
Your gateways, be they distribution layer switches or routers connecting the internet, will be organized into standby groups. Hot Standby Router Protocol, (HSRP) is the key word. Every action in HSRP includes the word “standby”.
It will be the “standby” IP address when you configure the virtual IP. It will be “#show standby” when you use the #show command for verification. It will be “# show standby” if you use the debug command.
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Start training All other gateways will remain on standby. Regardless of whether you have five backups or one, they will all be considered standby. There will also be one active and one primary.
What are HSRP Hold Timers and Hello Timers?
To ensure redundancy among routers, HSRP uses two types timers: hello and hold. The hello timer sends multicasts (or hello packets) that broadcast priority and status every three seconds. If you don’t tune into anything, the active routers and the standby routers will greet each other by default. The hold timer tells standby router when it should take over. The standby router is activated if it doesn’t receive a hello packet in 10 seconds from the primary router. In the worst case scenario, you have 10 seconds before a standby router can take over. The timer settings can also be adjusted to lower the time limit.
How do you read a HSRP Virtual MAC address?
Cisco purchased a lot of MAC addresses to use for their devices. Each section of the HSRP MAC addresses represents a different piece information — vendor ID and HSRP version identifiers, as well as standby group numbers.
First six characters: 0000.0C, Cisco vendor designation
Middle four characters: 07.AC. HSRP version (in our case version one).
Last two characters: xx, standby number
You can use 0 to 255 for the HSRP standby group. This means that you can have 256 HSRP group.
How to set HSRP Standby Group Priorities
HSRP is all in the priorities. If the top priority router fails, HSRP will search for the next-highest priority router. This is something you should do.
First, tell your switch that you are part of a standby list.
# standby 1 IP 172.30.70.2
Next, you will need to create active and standby groups. This command will assign the primary router. The default priority for HSRP is 100. You will need to give the primary router a higher priority that the standby. This group is designated as active with a priority of 110.
# standby group 1, priority 110
The switch with highest priority is active. The priority of the standby switches is lower. You can adjust how low you want to go, but it is important to plan increments for interface tracking.
What is HSRP Interface Monitoring?
Multiple router interfaces can act and appear as one virtual router with HSRP. What happens if one of the router interfaces goes down but the HSRP switch remains operational? You must reduce the priority of the