Configuration Guide User guide

FastIron Configuration Guide 647
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VSRP
• The backup priority is used for election of the Master. The VSRP Backup with the highest
priority value for the VRID is elected as the Master for that VRID. The default priority is 100. If
two or more Backups are tied with the highest priority, the Backup with the highest IP address
becomes the Master for the VRID.
• The track priority is used with the track port feature. Refer to “VSRP priority calculation” on
page 636 and “Changing the default track priority setting” on page 649.
To change the backup priority, enter a command such as the following at the configuration level for
the VRID.
Brocade(config-vlan-200-vrid-1)#backup priority 75
Syntax: [no] backup [priority <value>] [track-priority <value>]
The priority <value> parameter specifies the backup priority for this interface and VRID. Specify a
value as follows:
• For VRRP, specify a value from 3 – 254. The default is 100.
• For VSRP and VRRP-E, specify a value from 6 – 255. The default is 100.
For a description of the track-priority <value> parameter, refer to “Changing the default track
priority setting” on page 649.
Saving the timer values received from the master
The Hello messages sent by a VRID master contain the VRID values for the following VSRP timers:
• Hello interval
• Dead interval
• Backup Hello interval
• Hold-down interval
The Backups always use the value of the timers received from the Master.
To configure a Backup to save the VSRP timer values received from the Master instead of the timer
values configured on the Backup, enter the following command. Saving the current timer values
instead of the configured ones helps ensure consistent timer usage for all the VRID devices.
Brocade(config-vlan-200-vrid-1)#save-current-values
Syntax: [no] save-current-values
Changing the TTL setting
A VSRP Hello packet time to live (TTL) specifies how many hops the packet can traverse before
being dropped. A hop can be a Layer 3 Switch or a Layer 2 Switch. You can specify from 1 – 255.
The default TTL is 2. When a VSRP device (Master or Backup) sends a VSRP HEllo packet, the
device subtracts one from the TTL. Thus, if the TTL is 2, the device that originates the Hello packet
sends it out with a TTL of 1. Each subsequent device that receives the packet also subtracts one
from the packet TTL. When the packet has a TTL of 1, the receiving device subtracts 1 and then
drops the packet because the TTL is zero.
NOTE
An MRP ring is considered to be a single hop, regardless of the number of nodes in the ring.