TP-Link T3700G-28TQ T3700G-28TQ V1 UG - Page 210

Advantages of VRRP, Typical Networking Application Diagram, VRRP Operating Principle

Page 210 highlights

Hosts in LAN only recognize the IP address of the virtual router, but not that of the master router or backup routers. The IP address of the virtual router is assigned as the default gateway for the participating routers. Hosts in LAN communicate with external network via the virtual router. Once the master router in backup group fails, another router will be selected to replace it from the backup group through election protocol and thus provides routing service for hosts. Therefore, communication between hosts and external network can be established without interruption.  Advantages of VRRP VRRP owns the following advantages: 1. Simplified network management. In LAN with multicast or broadcast function, such as Ethernet, even though a device fails, with the help of VRRP, highly-reliable default link can still be provided and network interruption can be avoided after a single link fails without reconfiguration of dynamic routing or router discovery protocols, or default gateway configuration on every end-host. 2. Small network overhead. The single message that VRRP defines is the VRRP advertisement, which can only be sent by the master router.  Typical Networking Application Diagram Figure 10-56 Typical Networking Application Diagram  VRRP Operating Principle 1. Working Process VRRP backup group, or virtual router, consists of a group of physical routers with the same VRID (virtual route identifier). A virtual router owns one or more virtual IP addresses and one virtual MAC address, in the format 00-00-5E-00-01-{VRID}. The IP address of the virtual router is assigned as the default gateway for the hosts within the LAN. Communication with external network can be realized via the virtual router. Master router is selected from the physical routers in the virtual router group according to VRRP priority. The elected master router provides routing service to the hosts in LAN, and sends VRRP messages periodically to publicize its configuration information like priority and operating condition to other routers in backup group. Other physical routers in the backup group work as backup routers. They monitor the VRRP packets sent by the master router. A 199

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Hosts in LAN only recognize the IP address of the virtual router, but not that of the master router or
backup routers. The IP address of the virtual router is assigned as the default gateway for the
participating routers. Hosts in LAN communicate with external network via the virtual router. Once
the master router in backup group fails, another router will be selected to replace it from the
backup group through election protocol and thus provides routing service for hosts.
Therefore,
communication between hosts and external network can be established without interruption.
Advantages of VRRP
VRRP owns the following advantages:
1. Simplified network management. In LAN with multicast or broadcast function, such as
Ethernet, even though a device fails, with the help of VRRP, highly-reliable default link can
still be provided and network interruption can be avoided after a single link fails without
reconfiguration of dynamic routing or router discovery protocols, or default gateway
configuration on every end-host.
2. Small network overhead. The single message that VRRP defines is the VRRP
advertisement, which can only be sent by the master router.
Typical Networking Application Diagram
Figure 10-56 Typical Networking Application Diagram
VRRP Operating Principle
1. Working Process
VRRP backup group, or virtual router, consists of a group of physical routers with the same
VRID (virtual route identifier). A virtual router owns one or more virtual IP addresses and one
virtual MAC address, in the format 00-00-5E-00-01-{VRID}. The IP address of the virtual router
is assigned as the default gateway for the hosts within the LAN. Communication with external
network can be realized via the virtual router.
Master router is selected from the physical routers in the virtual router group according to
VRRP priority. The elected master router provides routing service to the hosts in LAN, and
sends VRRP messages periodically to publicize its configuration information like priority and
operating condition to other routers in backup group. Other physical routers in the backup
group work as backup routers. They monitor the VRRP packets sent by the master router. A
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