Brocade Multi-Service IronWare Switching Configuration Guide (Supporting R05.6.00) - Manual (Page 585)

Multi-Service IronWare Switching Configuration Guide 555
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Layer 2 redundancy
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NOTE
If the Brocade device is configured as the VSRP Master and it is connected to a FastIron switch
(FESX, FSX, SuperX, FGS, and FLS) that is operating as a VSRP-Aware device, the FastIron switch
must have the vsrp-aware tc-vlan-flush command configured at the VLAN level.
When the vsrp-aware tc-vlan-flush command is enabled on the FastIron switch, MAC addresses will
be flushed at the VLAN level, instead of at the port level. MAC addresses will be flushed for every
topology change (TC) received on the VSRP-aware ports.
Layer 2 redundancy
VSRP provides Layer 2 redundancy. This means that Layer 2 links are backed up.
You can configure VSRP to provide redundancy for Layer 2 only or also for Layer 3:
• Layer 2 only – The Layer 2 links are backup up but specific IP addresses are not backed up.
• Layer 2 and Layer 3 – The Layer 2 links are backup up and a specific IP address is also backed
up. Layer 3 VSRP is the same as VRRP-E. However, using VSRP provides redundancy at both
layers at the same time.
The Brocade device supports Layer 2 and Layer 3 redundancy. You can configure a Brocade device
for either Layer 2 only or Layer 2 and Layer 3. To configure for Layer 3, specify the IP address you
are backing up.
NOTE
If you want to provide Layer 3 redundancy only, disable VSRP and use VRRP-E.
Master election and failover
Each VSRP device advertises its VSRP priority in Hello messages. During Master election, the VSRP
device with the highest priority for a given VRID becomes the Master for that VRID. After Master
election, the Master sends Hello messages at regular intervals to inform the Backups that the
Master is healthy.
If there is a tie for highest VSRP priority, the tie is resolved as follows:
• Brocade devices – The Brocade device whose virtual routing interface has a higher IP address
becomes the master.
VSRP failover
Each Backup listens for Hello messages from the Master. The Hello messages indicate that the
Master is still available. If the Backups stop receiving Hello messages from the Master, the election
process occurs again and the Backup with the highest priority becomes the new Master.
Each Backup waits for a specific period of time, the Dead Interval, to receive a new Hello message
from the Master. If the Backup does not receive a Hello message from the Master by the time the
Dead Interval expires, the Backup sends a Hello message of its own, which includes the Backup's
VSRP priority, to advertise the Backup's intent to become the Master. If there are multiple Backups
for the VRID, each Backup sends a Hello message.