Ericsson ECN330, User Manual

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Configuring the ECN330-switch
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1553-KDU 137 365 Uen D 2006-06-16
Command Usage
Address Assignment
• The IP address assigned to the virtual router must already be
configured on the router that will be the Owner. In other words, the IP
address for the virtual router exists on one, and only one, router in the
virtual router group, and the network mask for the virtual router address
is derived from the Owner. The Owner will also assume the role of the
Master virtual router in the group.
• The interfaces of all routers participating in a virtual router group must
be within the same IP subnet.
• VRRP creates a virtual MAC address for the master router based on a
standard prefix, with the last octet equal to the group ID. When a backup
router takes over as the master, it continues to forward traffic addressed
to this virtual MAC address. However, the backup router cannot reply to
ICMP pings sent to addresses associated with the virtual group
because the IP address owner is off line.
Virtual Router Priority
• The Owner of the virtual IP address is automatically assigned the
highest possible virtual router priority of 255. The backup router with the
highest priority will become the master router if the current master fails.
However, because the priority of the virtual IP address Owner is the
highest, the original master router will always become the active master
router when it recovers.
• If two or more routers are configured with the same VRRP priority, the
router with the higher IP address is elected as the new master router if
the current master fails.
Preempting the Acting Master
• The virtual IP Owner has the highest priority, so no other router can
preempt it, and it will always resume control as the master virtual router
when it comes back on line. The preempt function only allows a backup
router to take over from another backup router that is temporarily acting
as the group master. If preemption is enabled and this router has a
higher priority than the current acting master when it comes on line, it
will take over as the acting group master.