Dell Brocade DCX, Configuration Manual

Page: 449 / 1436

BigIron RX Series Configuration Guide 377
53-1001810-01
Configuring RSTP parameters
13
The max-age <value> parameter specifies the amount of time the device waits to receive a hello
packet before it initiates a topology change. Possible values: 6 – 40 seconds. The default is 20
seconds.
The value of max-age must be greater than the value of forward-delay to ensure that the
downstream bridges do not age out faster than the upstream bridges (those bridges that are closer
to the root bridge).
The force-version <value> parameter forces the bridge to send BPDUs in a specific format. You can
specify one of the following values:
•
0 – The STP compatibility mode. Only STP (or legacy) BPDUs will be sent.
•
2 – The default. RST BPDUs will be sent unless a legacy bridge is detected. If a legacy bridge is
detected, STP BPDUs will be sent instead.
The priority <value> parameter specifies the priority of the bridge. You can enter a value from 0 –
65535. A lower numerical value means a the bridge has a higher priority. Thus, the highest priority
is 0. The default is 32768.
You can specify some or all of these parameters on the same command line.
Changing port parameters
The RSTP port commands can be enabled on individual ports or on multiple ports, such as all ports
that belong to a VLAN.
The RSTP port parameters are preconfigured with default values. If the default parameters meet
your network requirements, no other action is required.
You can change the following RSTP port parameters using the following methods.
BigIron RX(config)# vlan 10
BigIron RX(config-vlan-10)# rstp ethernet 1/5 path-cost 15 priority 64
At the VLAN configuration level of the CLI.
Syntax: rstp ethernet <slot> / <portnum> path-cost <value> | priority <value> | [admin-edge-port]
| [admin-pt2pt-mac] | [force-migration-check]
At the interface level of the CLI.
Syntax: rstp [admin-edge-port] | [admin-pt2pt-mac]
The ethernet <slot>/<portnum > parameter specifies the interface used.
The path-cost <value> parameter specifies the cost of the port’s path to the root bridge. RSTP
prefers the path with the lowest cost. You can specify a value from 1 – 20,000,000. Table 76
shows the recommended path cost values from the IEEE standards.
TABLE 76
Recommended path cost values of RSTP
Link speed Recommended (default) RSTP path
cost values Recommended RSTP path cost range
Less than 100 kilobits per second 200,000,000 20,000,000 – 200,000,000
1 Megabit per second 20,000,000 2,000,000 – 200,000,000
10 Megabits per second 2,000,000 200,000 – 200,000,000
100 Megabits per second 200,000 20,000 – 200,000,000