what is vrrp

Virtual Router Redundancy Protocol (VRRP) is a routing protocol proposed by IETF to solve the problem of single point of failure when static gateways are configured in LAN, 1998 The formal RFC2338 protocol standard has been launched this year.                                                                                                                                                                                                                     (Recommended study: phpstorm)

VRRP is widely used in edge networks. Its design goal is to support the failed transfer of IP data traffic under specific circumstances without causing confusion, allowing the host to Use a single router and maintain connectivity between routers even if the actual first-hop router fails.

VRRP is a selection protocol that dynamically assigns the responsibilities of a virtual router to one of the VRRP routers on the LAN. The VRRP router that controls the virtual router IP addresses is called the master router and is responsible for forwarding packets to these virtual IP addresses.

This selection process provides a dynamic failover mechanism once the primary router becomes unavailable, allowing the virtual router's IP address to serve as the default first-hop router for the end host. It is a LAN access device backup protocol.

All hosts in a local area network are set up with a default gateway, so that packets sent by the host whose destination address is not in this network segment will be sent to the Layer 3 switch through the default gateway, thus realizing the connection between the host and the external network. Network communication.

VRRP is a routing fault-tolerant protocol, which can also be called a backup routing protocol. All hosts in a local area network are set up with default routes. When the destination address sent by a host in the network is not in this network segment, the packet will be sent to the external router through the default route, thereby realizing communication between the host and the external network.

When the default router is down (that is, the port is closed), the internal host will not be able to communicate with the outside. If the router is set up with VRRP, then at this time, the virtual router will enable the backup router to achieve Network-wide communication.

In the VRRP protocol, there are two important concepts: VRRP router and virtual router, master router and backup router.

VRRP router refers to the router running VRRP, which is a physical entity; virtual router refers to the logical concept created by the VRRP protocol. A group of VRRP routers work together to form a virtual router.

The virtual router appears to the outside world as a logical router with a unique fixed IP address and MAC address.

Routers in the same VRRP group have two mutually exclusive roles:

Master router and backup router, a VRRP group There is only one router in the master role, and there can be one or more routers in the backup role. The VRRP protocol selects one from the router group as the master router, responsible for ARP parsing and forwarding IP data packets in the group. The other routers act as backup and are on standby. When the main router fails for some reason, one of the backup routers can be upgraded to the main router after a momentary delay. This switch is very fast and does not require Change IP address and MAC address, so the system is transparent to the end user.

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