Overview
5-66
• forward-time <4-30> – Sets the time (in seconds) after which (if this bridge
is the root bridge) each port changes states to learning and forwarding.
This value is used by all instances. The default value is 15 seconds.
• hello-time <1-10> – Sets the hello-time. The hello-time is the time in
seconds after which (if this bridge is the root bridge) all the bridges in a
bridged LAN exchange Bridge Protocol Data Units (BPDUs). A very low
value leads to excessive traffic on the network, while a higher value delays
the detection of topology change. This value is used by all instances. The
default value is 2 seconds.
• max-age <6-40> – Max-age is the maximum time in seconds for which (if
a bridge is the root bridge) a message is considered valid. This prevents
the frames from looping indefinitely. The value must be greater than twice
the value of the hello time plus one, but less than twice the value of the
forward delay minus one.
The allowable range for max-age is 6-40 seconds. Configure this value
sufficiently high, so that a frame generated by root can be propagated to
the leaf nodes without exceeding the max-age. Use this command to set
the max-age for a bridge. This value is used by all instances.
The default value of bridge max-age is 20 seconds.
• max-hops <7-127> – Specifies the maximum allowed hops for a BPDU in
an MST region. This parameter is used by all MST instances. To restore the
default value, use the no parameter with this command. The default max-
hops in a MST region is 20.
portfast
[bpdufilter|bpduguard](def
ault)
Enables the portfast feature on a bridge. It has the following options:
• bpdufilter (default) – Use the
bpdu-filter command to set the portfast
BPDU filter for the port. Use the no parameter with this command to revert
the port BPDU filter value to default.
The Spanning Tree Protocol sends BPDUs from all ports. Enabling the
BPDU Filter feature ensures PortFast enabled ports do not transmit or
receive BPDUs.
• bpduguard (default) – Use the
bpdu-guard command to enable the BPDU
(Bridge Protocol Data Unit) Guard feature on a bridge.
Use the
no parameter with this command to disable BPDU Guard.
When the BPDU Guard is set for a bridge, all portfast-enabled ports that
have the bpdu guard set to default shut down the port on receiving a BPDU.
In this case, the BPDU is not processed. The port can be brought back up
manually (using the no shutdown command), or by configuring a
errdisable-timeout to enable the port after the specified interval.
To Next Page
Loading...
Need help?
General
