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Mac address failover on vsrp-aware devices – Brocade FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide User Manual

Page 99

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In

Figure 15

, the track port is up. SInce the port is up, the track priority does not affect the VSRP

priority calculation. If the track port goes down, the track priority does affect VSRP priority calculation,
as shown in the following figure.

FIGURE 16 Track port priority subtracted during priority calculation

MAC address failover on VSRP-aware devices

VSRP-aware devices maintain a record of each VRID and its VLAN. When the device has received a
Hello message for a VRID in a given VLAN, the device creates a record for that VRID and VLAN and
includes the port number in the record. Each subsequent time the device receives a Hello message for
the same VRID and VLAN, the device checks the port number:

• If the port number is the same as the port that previously received a Hello message, the VSRP-aware

device assumes that the message came from the same VSRP Master that sent the previous
message.

• If the port number does not match, the VSRP-aware device assumes that a VSRP failover has

occurred to a new Master, and moves the MAC addresses learned on the previous port to the new
port.

The VRID records age out if unused. This can occur if the VSRP-aware device becomes disconnected
from the Master. The VSRP-aware device will wait for a Hello message for the period of time equal to
the following.

VRID Age = Dead Interval + Hold-down Interval + (3 x Hello Interval)

The values for these timers are determined by the VSRP device sending the Hello messages. If the
Master uses the default timer values, the age time for VRID records on the VSRP-aware devices is as
follows.

3 + 3 + (3 x 1) = 9 seconds

In this case, if the VSRP-aware device does not receive a new Hello message for a VRID in a given
VLAN, on any port, the device assumes the connection to the Master is unavailable and removes the
VRID record.

MAC address failover on VSRP-aware devices

FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide

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