Install guide

Rapier Layer 3 Gigabit Switch Software Release 2.1.0 41
Rapier Switch Software Release 2.1.0
C613-10200-01 Rev A
same STP. Within any given STP, all VLANs belonging to it use the same
Spanning Tree.
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The topology of the VLAN is dynamic. The structure of the VLAN may
change due to new devices requesting or releasing the services available
via the VLAN. The dynamic nature of VLANs has the advantages of
flexibility and bandwidth conservation, at the cost of network
management complexity.
Multiple Spanning Trees in a VLAN environment have not been standardised. This
means the BPDUs used in communicating Spanning Tree Algorithm parameters are
vendor specific, since the BPDUs defined by IEEE std 802.1D are based on a single
Spanning Tree and do not have any reference to VLANs. A LAN comprising switches
from more than one vendor should, therefore, only use the single default STP. Multiple
STPs should not be created.
Configuring STP
By default, the switch has one default STP which cannot be destroyed. In most
situations this default STP will suffice. However, further instances of the
Spanning Tree Protocol (STPs) can be created and destroyed using the
commands:
CREATE STP=stpname
DESTROY STP={stpname|ALL}
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:
ADD STP=stpname VLAN={vlanname|2..4094}
DELETE STP=stpname VLAN={vlanname|2..4094|ALL}
The default STP is enabled by default at switch start up, while STPs created by
a user are disabled by default when they are created. 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 the STP information on which the dynamic
STP topology depends: the HELLOTIME, FORWARDDELAY and MAXAGE
parameters. All switches in the STP use the values for these parameters sent by
the root bridge and forwarded by the designated bridges. A particular switch
may be configured with different time intervals, which would be used by the
whole spanning tree if this switch became the root bridge.
The HELLOTIME parameter, with a default value of 2 seconds, determines
how often the switch sends Hello messages containing spanning tree
configuration information if it is the root bridge, or is trying to become the root
bridge in the network. Setting a shorter value for HELLOTIME than the default
of 2 seconds makes the network more robust; setting a longer time uses less
processing overheads.
The MAXAGE parameter, with a default of 20 seconds, determines the
maximum time that dynamic STP configuration information is stored in the
switch, before it is considered too old, and discarded. The value can be set at
approximately two seconds for every hop across the network. If this value is
too small, the STP may sometimes configure unnecessarily. If it is too long,