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Chapter 6 Advanced Application Configurations
Table 15 Mult iple Spanning Tree Prot ocol Screen
LABEL
DESCRIPTION
Max Age
This is t he m axim um t im e ( in seconds) t he Swit ch can wait wit hout receiving a BPDU
before at t em pt ing t o reconfigure. All Swit ch port s ( except for designat ed port s) should
receive BPDUs at regular int ervals. Any port t hat ages out STP inform at ion ( provided
in t he last BPDU) becom es t he designat ed port for t he at t ached LAN. I f it is a root
port , a new root port is select ed from am ong t he Swit ch port s at t ached t o t he
net work. The allowed range is 6 t o 40 seconds.
Forwarding Delay
This is t he m axim um t im e ( in seconds) t he Swit ch will wait before changing st at es.
This delay is required because every swit ch m ust receive inform at ion about t opology
changes before it st art s t o forward fram es. I n addit ion, each port needs t im e t o list en
for conflict ing inform at ion t hat would m ake it ret urn t o a blocking st at e; ot herwise,
t em porary dat a loops m ight result . The allowed range is 4 t o 30 seconds. As a general
rule:
Note: 2 * (Forward Delay - 1) >= Max Age >= 2 * (Hello Time + 1)
Maxim um hops
Ent er t he num ber of hops ( bet ween 1 and 255) in an MSTP region before t he BPDU is
discarded and t he port inform at ion is aged.
Configurat ion Nam e
Ent er a descript ive nam e ( up t o 32 charact ers) of an MST region.
Revision Num ber
Ent er a num ber t o ident ify a region's configurat ion. Devices m ust have t he sam e
revision num ber t o belong t o t he sam e region.
Apply
Click Apply t o save your changes t o t he Swit ch's run- t im e m em ory. The Swit ch loses
t hese changes if it is t urned off or loses power.
Cancel
Click Ca n ce l t o begin configuring t his screen afresh.
I nst ance
I nst ances can be added or rem oved from t he t able. For exam ple, if inst ance 1 is added
wit h inst ance priorit y 20480 ( default is 32768) , t hen it m irrors VLAN 10 - 20. The port
st at us for MSTP spanning t ree can be configured; configurat ion is ident ical t o t he RSTP
port .
I nst ance
Ent er t he num ber you want t o use t o ident ify t his MST inst ance on t he Swit ch. The
Swit ch support s inst ance num bers 0- 15.
Bridge Priorit y
Set t he priorit y of t he Swit ch for t he specific spanning t ree inst ance. The lower t he
num ber, t he m ore likely t he Swit ch will be chosen as t he root bridge wit hin t he
spanning t ree inst ance.
Ent er priorit y values bet ween 0 and 61440 in increm ent s of 4096 ( t hus valid values
are 4096, 8192, 12288, 16384, 20480, 24576, 28672, 32768, 36864, 40960, 45056,
49152, 53248, 57344 and 61440) .
VLAN Range
Ent er t he st art of t he VLAN I D range t hat you want t o add or rem ove from t he VLAN
range edit area in t he St a r t field. Ent er t he end of t he VLAN I D range t hat you want t o
add or rem ove from t he VLAN range edit area in t he En d field.
Next click:
•
•
•
Port
This field displays t he port num ber.
*
Set t ings in t his row apply t o all port s.
Use t his row only if you want t o m ake som e set t ings t he sam e for all port s. Use t his
row first t o set t he com m on set t ings and t hen m ake adj ust m ent s on a port- by- port
basis.
Note: Changes in this row are copied to all the ports as soon as you make them.
Act ive
Select t his check box t o add t his port t o t he MST inst ance.
Add - t o add t his range of VLAN( s) t o be m apped t o t he MST inst ance.
Re m ove - t o rem ove t his range of VLAN( s) from being m apped t o t he MST
inst ance.
Cle a r - t o rem ove all VLAN( s) from being m apped t o t his MST inst ance.
MGS3750-28F User's Guide
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