ccna for beginners

ccna for beginners.(1) Virtual Router A VirtualRouter is a group of routers that is called a hot backup group, and the virtual router has its own virtual IP address and virtual MAC address. In HSRP version 1, the virtual MAC address format is 0000.0c07.acXX,where XX denotes the group number, which means HSRP version 1 supports up to 255 groups; and in HSRP version 2, the virtual MAC address format is 0000.0c9f.fYYY, where YYY denotes the group number, which means HSRP version 2 supports up to 4095 groups.(2) Active RouterIn an HSRP group, only one router is selected as the active router, which is responsible for responding to ARP requests sent by hosts in the group and forwarding packets sent to the MAC address of the virtual router.(3) Backup Router ( StandbyRouter)Chapter 15 EtherChannel and FHRP .253.The backup router ( StandbyRouter) listens for periodic Hello (default send period is 3 seconds) messages. the backup router takes over the role of the active router if the active router fails and the other HSRP routers are unable to receive the Hello messages it sends for the maintenance time (default is 10 seconds). An HSRP group has only one backup router.(4) Other Routers An HSRP group can have multiple routers, but there is only one active router and one backup router, and the other routersare kept in the listening state. If the preemption function is configured, when the active router or backup router fails, all other routers will participate in the preemption and become the active router or backup router through competition.(5) HSRP Versions Currently, HSRP includes version 1 and version 2 (use the command standby version2 under the port to configure HSRP version 2), but the two versions are not compatible. The default version of HSRP running on the router is version 1. Both versions operate on UDP, with the source and destination ports