Virtual Router Redundancy Protocol (VRRP) | 633
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Virtual Router Redundancy Protocol (VRRP)
This chapter covers the following information:
• Overview
• VRRP Benefits
• VRRP Implementation
• VRRP Configuration
• Sample Configurations
Overview
Virtual router redundancy protocol (VRRP) is designed to eliminate a single point of failure in a statically
routed network.
VRRP specifies a MASTER router that owns the next hop IP and MAC address for end stations on a local
area network (LAN). The MASTER router is chosen from the virtual routers by an election process and
forwards packets sent to the next hop IP address. If the MASTER router fails, VRRP begins the election
process to choose a new MASTER router and that new MASTER continues routing traffic.
VRRP uses the virtual router identifier (VRID) to identify each virtual router configured. The IP address of
the MASTER router is used as the next hop address for all end stations on the LAN. The other routers
represented by IP addresses are BACKUP routers.
VRRP packets are transmitted with the virtual router MAC address as the source MAC address. The MAC
address is in the following format: 00-00-5E-00-01-{VRID}. The first three octets are unchangeable. The
next two octets (00-01) indicate the address block assigned to the VRRP protocol, and are unchangeable.
The final octet changes depending on the VRRP VRID and allows for up to 255 VRRP routers on a
network.
Figure 38-1 shows a typical network configuration using VRRP. Instead of configuring the hosts on the
network 10.10.10.0 with the IP address of either Router A or Router B as their default router; their default
router is the IP address configured on the virtual router. When any host on the LAN segment wants to
access the Internet, it sends packets to the IP address of the virtual router.
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