Fast Uplink Span - Foundry Networks Switch and Router Installation And Configuration Manual

Foundry Switch and Router Installation and Configuration Guide
Syntax: [no] fast port-span [exclude ethernet <portnum> [ethernet <portnum>... | to <portnum>]]
To re-enable Fast Port Span on a port, enter a command such as the following:
BigIron(config)# no fast port-span exclude ethernet 1/1
BigIron(config)# write memory
This command re-enables Fast Port Span on port 1/1 only and does not re-enable Fast Port Span on other
excluded ports. You also can re-enable Fast Port Span on a list or range of ports using the syntax shown above
this example.
To re-enable Fast Port Span on all excluded ports, disable and then re-enable Fast Port Span by entering the
following commands:
BigIron(config)# no fast port-span
BigIron(config)# fast port-span
BigIron(config)# write memory
Disabling and then re-enabling Fast Port Span clears the exclude settings and thus enables Fast Port Span on all
eligible ports. To make sure Fast Port Span remains enabled on the ports following a system reset, save the
configuration changes to the startup-config file after you re-enable Fast Port Span. Otherwise, when the system
resets, those ports will again be excluded from Fast Port Span.
USING THE WEB MANAGEMENT INTERFACE
You cannot exclude individual ports from Fast Span using the Web management interface.

Fast Uplink Span

The Fast Port Span feature described in the previous section enhances STP performance for end stations. The
Fast Uplink feature enhances STP performance for wiring closet switches with redundant uplinks. Using the
default value for the standard STP forward delay, convergence following a transition from an active link to a
redundant link can take 30 seconds (15 seconds for listening and an additional 15 seconds for learning).
You can use the Fast Uplink feature on a Foundry device deployed as a wiring closet switch to decrease the
convergence time for the uplink ports to another device to just four seconds (two seconds for listening and two
seconds for learning). The wiring closet switch must be a Foundry device but the device at the other end of the
link can be a Foundry device or another vendor's switch. Configuration of the Fast Uplink Span feature takes
place entirely on the Foundry device.
To configure the Fast Uplink Span feature, specify a group of ports that have redundant uplinks on the wiring
closet switch (Foundry device) as members of a Fast Uplink Group. If the active link becomes unavailable, the
Fast Uplink Span feature transitions the forwarding to one of the other ports in four seconds. You can configure
one Fast Uplink Span group on the device. All Fast Uplink Span ports are members of the same Fast Uplink Span
group.
NOTE: To avoid the potential for temporary bridging loops, Foundry Networks recommends that you use the
Fast Uplink feature only for wiring closet switches (switches at the edge of the network cloud). In addition, enable
the feature only on a group of ports intended for redundancy, so that at any given time only one of the ports is
expected to be in the forwarding state.
NOTE: When the wiring closet switch (Foundry device) first comes up or when STP is first enabled, the uplink
ports still must go through the standard STP state transition without any acceleration. This behavior guards
against temporary routing loops as the switch tries to determine the states for all the ports. Fast Uplink Span
acceleration applies only when a working uplink becomes unavailable.
Fast Uplink Span Rules for Trunk Groups
If you add a port to a Fast Uplink Span group that is a member of a trunk group, the following rules apply:
• If you add the primary port of a trunk group to the Fast Uplink Span group, all other ports in the trunk group
are automatically included in the group. Similarly, if you remove the primary port in a trunk group from the
Fast Uplink Span group, the other ports in the trunk group are automatically removed from the Fast Uplink
Span group.
12 - 18 December 2000