HSRP (hot standby routig protectol) hot standby routing protocol: It is a proprietary technology of Cisco. It works basically the same as VRRP.
1. Concept of HSRP
(1) Overview: By establishing virtual router groups and virtual mac addresses to achieve IP network redundancy backup (layer 3 network routing), HSRP enables Cisco routers in the group to monitor each other's running status.
(2) Composition: ① Active router: forwards the data packets sent to the virtual router.
② Backup router: Monitor the running status of HSRP, and quickly assume the responsibility of forwarding data packets when the active router fails to operate.
③ Virtual router: provide end users with a router that can work continuously.
④ Other routers: monitor the Hello message but do not respond.
(3) Virtual mac address: The IP address and corresponding MAC address of the virtual router are maintained in the ARP table of the meter-Taiwan Layer 3 switch in the HSRP group.
(4) Working principle Redundant backup of IP network is realized by selecting active router, backup router, virtual router and other routers to send protocol packets through UPD port. It is achieved through three steps:
① Selecting the active router: Each router in the HSRP group has a designated priority, which is used to measure the priority of the router in the selection of active routers. (Priority + IP address) A router with a high priority and a large IP address.
② Select the backup router: Each router in the HSRP group has a specified priority, which is used to measure the priority of the router in the selection of the backup router. (Priority + IP address) A router with a high priority and a large IP address.
③ Select another router.
(5) HSRP configuration status:
① Initial status: HSRP is not running yet, the status is entered when the configuration changes or the first port is enabled for the first time.
②-Address.
④Monitoring state: The IP address of the virtual router is known, but it is neither an active route nor a backup route. It monitors the elections from the active route and the backup route.
⑤ Speaking state: The router sends periodic Hello messages and participates in the election of an active router or a backup router.
⑥ Active state: The router is responsible for forwarding the data packets sent to the virtual MAC address of the backup group. Active routers send Hello messages periodically.
Ps:Hello information: ①Interval timer: HSRP routers in any state will generate Hello packets after the Hello interval timer expires. The default Hello interval is 3s, and the default hold time is 10s.
②Hold time timer: Other HSRP routers monitor active routers according to the hold time.
(6) Failure: ① Preemption: Help the failed active router with a higher priority to restore the active router identity.
②Port tracking: The priority of active routers is automatically adjusted based on the availability of ports.
2. HSRP configuration and application
(1) Configure HSRP members:
(config-if)#standby group-number (group number) ip virtual-ip-address (virtual IP address)
(2) Priority:
(config-if)#standby group-number (group number) priority-value (number of priorities)
(3) Preemption:
(config-if) #standby group-number preempt
(4) Port tracking:
(config-if) #standby group-number (port group using the tracking function number) track interface-type (tracking port port type) mod/num (port number of tracking port) interface-priority (decreasing level)
(5) Configure the timer for the Hello relationship:
(config-if) #standby group- number (group number) times hellotime (interval time number) holdtime (hold time number)
(6) Check the HSRP status:
(config-if) #show standby [interface-type mod/num] (port type and serial number) [group- number] (group number) brief