Edge-Core ECS4620-28T Quick Start Manual page 695

Command Usage
Address Assignment –
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To designate a specific router as the VRRP master, the IP address assigned to the
virtual router must already be configured on the router that will become the
Owner of the group address. 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.
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If a virtual address is assigned to the group which does not exist on any of the
group members, then the master router is selected based on priority. In cases
where the configured priority is the same on several group members, then the
master router with the highest IP address is selected from this group.
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If you have multiple secondary addresses configured on the current VLAN
interface, you can add any of these addresses to the virtual router group.
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The interfaces of all routers participating in a virtual router group must be
within the same IP subnet.
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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 –
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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.
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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 –
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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 a master router if no router in the group is the virtual IP owner, or 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.
Chapter 18
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| Configuring Router Redundancy
Configuring VRRP Groups