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DES-3028 DES-3028P DES-3052 DES-3052P  Layer 2 Fast Ethernet Switch CLI Reference Manual 
11 
M
ULTIPLE 
S
PANNING 
T
REE 
P
ROTOCOL 
(MSTP) C
OMMANDS
 
This Switch supports three versions of the Spanning Tree Protocol; 802.1d STP, 802.1w Rapid STP and 802.1s MSTP. Multiple 
Spanning Tree Protocol, or MSTP, is a standard defined by the IEEE community that allows multiple VLANs to be mapped to a 
single spanning tree instance, which will provide multiple pathways across the network. Therefore, these MSTP configurations 
will balance the traffic load, preventing wide scale disruptions when a single spanning tree instance fails. This will allow for faster 
convergences of new topologies for the failed instance. Frames designated for these VLANs will be processed quickly and 
completely throughout interconnected bridges utilizing either of the three spanning tree protocols (STP, RSTP or MSTP). This 
protocol will also tag BDPU packets so receiving devices can distinguish spanning tree instances, spanning tree regions and the 
VLANs associated with them. These instances will be classified by an instance_id. MSTP will connect multiple spanning trees 
with a Common and Internal Spanning Tree (CIST). The CIST will automatically determine each MSTP region, its maximum 
possible extent and will appear as one virtual bridge that runs a single spanning tree. Consequentially, frames assigned to different 
VLANs will follow different data routes within administratively established regions on the network, continuing to allow simple 
and full processing of frames, regardless of administrative errors in defining VLANs and their respective spanning trees. Each 
switch utilizing the MSTP on a network will have a single MSTP configuration that will have the following three attributes: 
a)  A configuration name defined by an alphanumeric string of up to 32 characters (defined in the config stp mst_config_id 
command as name <string>). 
b) A 
configuration 
revision 
number (named here as a revision_level) and; 
c)  A 4094 element table (defined here as a vid_range) which will associate each of the possible 4094 VLANs supported by 
the Switch for a given instance. 
 To utilize the MSTP function on the Switch, three steps need to be taken: 
a)  The Switch must be set to the MSTP setting (config stp version
b)  The correct spanning tree priority for the MSTP instance must be entered (config stp priority). 
c)  VLANs that will be shared must be added to the MSTP Instance ID (config stp instance_id).  
The Multiple Spanning Tree Protocol commands in the Command Line Interface (CLI) are listed (along with the appropriate 
parameters) in the following table. 
Command Parameters 
enable stp 
 
disable stp 
 
config stp version 
[mstp | rstp | stp] 
config stp 
{maxage <value 6-40> | maxhops <value 1-20> | hellotime <value 1-10> | 
forwarddelay <value 4-30>| txholdcount <value 1-10> | fbpdu [enable | disable] | 
lbd [enable | disable] | lbd_recover_timer [0 | <value 60-1000000>]} 
config stp ports 
<portlist> {externalCost [auto | <value 1-200000000>] | hellotime <value 1-10> | 
migrate [yes | no] | edge [true | false] | p2p [true | false | auto] | state [enable | 
disable] | lbd [enable | disable] | fbpdu [enable |disable]} 
create stp instance_id 
<value 1-4> 
config stp instance _id  <value 1-4> [add_vlan | remove_vlan] <vidlist> 
delete stp instance_id 
<value 1-4> 
config stp priority 
<value 0-61440> instance_id <value 0-4> 
config stp 
mst_config_id 
{revision_level <int 0-65535> | name <string>} 
config stp mst_ports 
<portlist> instance_id <value 0-4> {internalCost [auto | value 1-200000000] | 
priority <value 0-240>} 
show stp 
 
show stp ports 
{<portlist>} 
 
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