Owner manual

Chapter 30: Virtual Router Redundancy Protocol
346 Section VII: Routing
Master Switch
The virtual router has a virtual MAC address known by all the switches
participating in the virtual router. The virtual MAC address is derived from
the virtual router identifier, which is a user-defined value from 1 to 255. All
hosts on the LAN are configured with an IP address to use as the first hop.
This IP address is typically owned by the preferred switch in the group of
switches that constitute the virtual router. When available, this switch
performs the duties of the virtual router, and is referred to as the master.
The switch that owns the IP address associated with the virtual router is
referred to as the preferred master. When a virtual router is configured so
that none of the participating switches owns the IP address, the virtual
router has no preferred master.
When a switch takes the role of master for a virtual router, it does the
following:
 Responds to ARP packets for the IP addresses associated with the virtual
router. The ARP response contains the virtual MAC address of the virtual
router so that the hosts on the LAN associate the virtual MAC address with
their configured first hop IP address.
 Forwards packets with a destination link layer MAC address equal to the
virtual router MAC address.
 Accepts packets addressed to the IP address(es) associated with the virtual
router, but only if it actually owns the address(es).
 Broadcasts advertisement packets at regular intervals (at the specified
advertisement interval) to inform backup switches that it is still acting as the
master switch.
In accordance with the RFC standard, a user does not receive a response
to ping or Telnet packets sent to the VR address unless the switch owns
this address.