Important Considerations - 3Com 4007 Implementation Manual

Important
Considerations
VRRP provides for this by making you assign each virtual router on the
LAN a priority value between 1 and 255. (255 means that the virtual
router is the actual owner of the IP addresses.) If the Master fails, the
virtual router with the next-highest priority takes over Master
responsibilities until the original Master comes back online.
If two routers have the same priority, VRRP resolves the conflict by
selecting the virtual router with the numerically-highest primary IP
address. In other words, if Virtual Router A (primary IP address of 1.1.1.2)
and Virtual Router C (primary IP address of 1.1.1.3) both have a priority of
100, Virtual Router C would have a higher priority than Virtual Router A.
CAUTION: Configure all of the routers participating in the VRRP scheme
on your network to have the same representation of the network. If some
routers have a different view of the topology than others, a backup
router failure is more likely, with the resultant loss of some or all end
hosts' connection to the network.
This section provides information to be aware of when you implement
VRRP:
The Master router forwards the IP addresses that you have associated
with the primary virtual router, and:
Responds to ARP requests for the IP address or addresses that are
associated with the virtual router.
Forwards packets that have a destination Link Layer MAC address
that matches the virtual router MAC address. In other words, the
Master forwards packets that hosts have sent to the virtual router
to be routed.
Discards packets addressed to the IP address or addresses
associated with the virtual router if the virtual router is not the IP
address owner. Otherwise, ping, SNMP, and Telnet do not function
properly.
Sends periodic VRRP advertisement messages. (Set the advertising
interval to be short enough to provide a timely transition to
another router should the Master fail. Try an advertising interval of
1 second.)

Important Considerations

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