Specifications

ExtremeWare XOS 10.1 Command Reference Guide 409
11 VRRP Commands
This chapter describes the following commands:
• Commands for enabling and disabling Virtual Router Redundancy Protocol (VRRP)
• Commands for performing basic VRRP configuration
Like ESRP, VRRP is a protocol that allows multiple switches to provide redundant routing services to
users. A virtual router is a group of one or more physical devices that acts as the default gateway for
hosts on the network. The virtual router is identified by a virtual router identifier (VRID) and an IP
address. All of the VRRP routers that participate in the virtual router are assigned the same VRID.
Extreme Networks’ VRRP implementation is compliant with RFC 2338, Virtual Router Redundancy
Protocol.
The following points pertain to VRRP:
• VRRP packets are encapsulated IP packets.
• The VRRP multicast address is 224.0.0.18.
• The virtual router MAC address is 00 00 5E 00 01 <vrid>
• An interconnect link between VRRP routers should not be used, except when VRRP routers have
hosts directly attached.
• A maximum of 64 VRID instances are supported on the router.
• Up to 7 unique VRIDs can be configured on an interface. VRIDs can be re-used, but not on the same
interface.
• VRRP and Spanning Tree can be simultaneously enabled on the same switch.
• VRRP and ESRP cannot be simultaneously enabled on the same switch.
VRRP uses an election algorithm to dynamically assign responsibility for the master router to one of the
VRRP routers on the network. A VRRP router is elected master if one of the following is true:
• The router is the IP address owner (router that has the IP address of the virtual router configured as
its real interface address).
• The router is configured with the highest priority (the range is 1 - 255).
In the event of a tie in priority, the highest primary IP address has precedence.
If the master router becomes unavailable, the election process provides dynamic failover and the backup
router that has the highest priority assumes the role of master.