Check also how to configure VRRP on Cisco IOS.CCNA Routing and Switching 200-120 Network Simulator Otherwise, when preempt is enabled, it could make change in standby/active routers what is not desired in production network.Ĭheck also how to configure GLBP on Cisco IOS. Notice that R3’s HSRP priority is set lower than R1’s and R2’s. R3(config-if)# standby 1 priority 101 R3(config-if)# standby 1 preempt delay minimum 10 R3(config)# interface GigabitEthernet 0/1 To configure router 3 as a “backup standby” HSRP router: from standby to active or its link goes down. Change of router state from listen to standby will be preformed only if previous standby router will change its own status, e.g. It will hang around and listen HSRP messages as long as it will not be needed. Every next configured router in this group will be participating in election but officially will never be a standby router. One HSRP instance can only have 1 active and 1 standby routers. Both are not compatible to each other – both sides of interfaces must have identical version.HSRP versions 1 and 2 have different packets format,.Hello packets multicast address is 224.0.0.102.Active router will send hello messages with source MAC address of the physical interface MAC address,.Hello packet multicast address is 224.0.0.2.Active router will send hello messages with source MAC address of the HSRP virtual MAC address,.Preempt delay feature delays preemption for a configurable period of time. To allow router advertise its routing table in the network, the preempt delay function comes in handy. Changing standby priority will not take any results as long as preempt is not enabled.
Priority is determined first by the value that is configured at the interface, and then by highest interface IP address. Router with the the highest priority become the Active Router immediately. R2(config-if)# standby 1 priority 120 R2(config-if)# standby 1 preempt delay minimum 10 R2(config)# interface GigabitEthernet 0/1 To configure also router 2 as a standby HSRP router: R1(config-if)# standby 1 priority 105 R1(config-if)# standby 1 preempt delay minimum 10 R1(config)# interface GigabitEthernet 0/1 To configure router 1 as active HSRP router follow commands bellow: The router sends periodic hello messages. active – router currently forwards packets that are sent to the group virtual MAC address.standby – router is a candidate to become the next active router and sends periodic hello messages,.speak – router sends periodic hello messages and actively participates in the election of the active and/or standby router,.listen – router listens for hello messages form active/standby routers,.learn – router still waits to hear from the active router,.initial – state which is entered through a configuration change or when an interface first becomes available,.This technology is very useful in High-Availability network infrastructures.īefore router will become an active it has to go through several HSRP states: The process of transferring the routing responsibilities from one device to another is transparent to the user. The routers share the same IP and MAC addresses, therefore in the event of failure of one router, the hosts on the LAN are able to continue forwarding packets to a consistent IP and MAC address. Using HSRP, several routers are connected to the same segment of an Ethernet, FDDI or token-ring network and work together to present the appearance of a single virtual router on the LAN. It is a routing protocol that provides backup to a router in the event of link or hardware failure. The Hot Standby Routing Protocol is a proprietary protocol from Cisco. Technology: Routing Area: NHRP Vendor: Cisco Software: 10.0, 10.2-3, 11.0-3, 12.0, 12.0T, 12.1, 12.1T Platform: Catalyst platforms, Routing platforms
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