Allied Telesis at-8516f User Guide
92
Rapier Switch User Guide
Software Release 2.6.1
C613-02025-00 REV C
C613-02025-00 REV C
Configuring STP
By default, the switch has one default STP which cannot be destroyed. In most
situations this default STP will suffice.
situations this default STP will suffice.
By default, all VLANs, and therefore all ports, belong to the default STP. To add
or delete a VLAN and all the ports belonging to it from any other STP, use the
commands:
or delete a VLAN and all the ports belonging to it from any other STP, use the
commands:
ADD STP=stpname VLAN={vlan-name|2..4094}
DELETE STP=stpname VLAN={vlan-name|2..4094|ALL}
The default STP is disabled by default at switch start up, and STPs created by a
user are disabled by default when they are created. An STP must be enabled
before STP can be enabled or disabled on particular ports belonging to it. To
enable or disable STPs, use the commands:
user are disabled by default when they are created. An STP must be enabled
before STP can be enabled or disabled on particular ports belonging to it. To
enable or disable STPs, use the commands:
ENABLE STP{=stpname|ALL}
DISABLE STP={stpname|ALL}
The Spanning Tree Protocol uses three configurable parameters for the time
intervals that control the flow of STP information on which the dynamic STP
topology depends: the HELLOTIME, FORWARDDELAY and MAXAGE
parameters. All switches in the same spanning tree topology must use the same
values for these parameters, but can themselves be configured with different,
and potentially incompatible time intervals. The parameter values actually
used by each switch are those sent by the root bridge, and forwarded to all
other switches by the designated bridges.
intervals that control the flow of STP information on which the dynamic STP
topology depends: the HELLOTIME, FORWARDDELAY and MAXAGE
parameters. All switches in the same spanning tree topology must use the same
values for these parameters, but can themselves be configured with different,
and potentially incompatible time intervals. The parameter values actually
used by each switch are those sent by the root bridge, and forwarded to all
other switches by the designated bridges.
The FORWARDDELAY parameter sets the time, in seconds, used to control
how fast a port changes its spanning state when moving towards the
Forwarding state. The value determines how long the port stays in each of the
Listening and Learning states which precede the Forwarding state. This value
is only used when the switch is acting as the Root Bridge. Any switch not
acting as the Root Bridge uses a dynamic value for the FORWARDDELAY set
by the Root Bridge. The FORWARDDELAY, MAXAGE and HELLOTIME
parameters are interrelated. See the note and formulae below. The default
value for FORWARDDELAY is 15 seconds.
how fast a port changes its spanning state when moving towards the
Forwarding state. The value determines how long the port stays in each of the
Listening and Learning states which precede the Forwarding state. This value
is only used when the switch is acting as the Root Bridge. Any switch not
acting as the Root Bridge uses a dynamic value for the FORWARDDELAY set
by the Root Bridge. The FORWARDDELAY, MAXAGE and HELLOTIME
parameters are interrelated. See the note and formulae below. The default
value for FORWARDDELAY is 15 seconds.
The HELLOTIME parameter sets the time, in seconds, between the
transmission of switch spanning tree configuration information when the
switch is the Root Bridge of the spanning tree or is trying to become the Root
Bridge. The default value is 2 seconds.
transmission of switch spanning tree configuration information when the
switch is the Root Bridge of the spanning tree or is trying to become the Root
Bridge. The default value is 2 seconds.
The MAXAGE parameter sets the maximum age, in seconds, of Spanning Tree
Protocol information learned over the network on any port before it is
discarded. The default value is 20 seconds.
Protocol information learned over the network on any port before it is
discarded. The default value is 20 seconds.
The FORWARDDELAY, MAXAGE and HELLOTIME parameters should be set
according to the following formulae, as specified in IEEE Standard 802.1D:
2 x (FORWARDDELAY - 1.0 seconds) >= MAXAGE
MAXAGE >= 2 x (HELLOTIME + 1.0 seconds)
according to the following formulae, as specified in IEEE Standard 802.1D:
2 x (FORWARDDELAY - 1.0 seconds) >= MAXAGE
MAXAGE >= 2 x (HELLOTIME + 1.0 seconds)
To modify the parameters controlling these time intervals, use the command:
SET STP={stp-name|ALL} [FORWARDDELAY=4..30] [HELLOTIME=1..10]
[MAXAGE=6..40] [other parameters]
The value of the PRIORITY parameter is used to set the writable portion of the
bridge ID, i.e. the first two octets of the (8-octet long) Bridge Identifier. The
remaining 6 octets of the bridge ID are given by the MAC address of the
bridge ID, i.e. the first two octets of the (8-octet long) Bridge Identifier. The
remaining 6 octets of the bridge ID are given by the MAC address of the