10-24-2007 05:43 AM - edited 03-05-2019 07:17 PM
I want to set up the forwarding time to 12 sec. please let me know how to do .
10-24-2007 05:50 AM
Are you talking about spanning tree forwarding?
SW1(config)#spanning-tree vlan 1 forward-time 6
listening
learning
forwarding
10-24-2007 05:53 AM
your answer is 100% correct. But please let me know how to calculate this.
shivlu
10-24-2007 05:54 AM
Are you running PVST? This must be done on the root:
spanning-tree vlan n forward-time 12
This will give you 12 seconds of listening state and 12 seconds of learning.
That is OK provided the diameter of your network is less than about 5 switches. Otherwise you could be introducing some instability.
Kevin Dorrell
Luxembourg
10-24-2007 05:57 AM
yeh my diameter is less than 4 switches. But still i am not clear. Do you have the formula for the same.
becasue i want to set the forward time to 20 seconds thn i donot want to disturb you again. So please let me know how to calculate this.
regards
shivlu
10-24-2007 06:00 AM
Kevin
If he wants the switchport to forward 12 seconds after the port is UP/UP will he need to use 6
6 learning
6 forwarding
spanning-tree vlan n forward-time 6
10-24-2007 06:04 AM
y u right mark, kevin the same i was trying what you said but it wonot work.
So mark if i want to set the forard time to 20 seconds thn i have to use the command
spnnaing tree vlanid forward 10
shivlu
10-24-2007 06:14 AM
yes i think so
10-24-2007 07:22 AM
10-24-2007 06:25 AM
Best practices indicate, not to vary STP timers but diameter, which then automatically varies the timers based on calculation.
Command is:
spanning-tree vlan vlanid# root primary diameter {No.}
This has to be configured on the root bridge. The diameter value will not be reflected in configuration, only the timer values will be displayed.
10-24-2007 08:32 AM
Best practices mainly indicate that you need to know what you're doing when you plan on tuning STP timers;-) What are you trying to achieve? Why do you say that tuning the forward time does not work? (is it based on the port going to forwarding using a different timer, the show command? or the CLI confusing you?)
c3750-ts37#sh span vlan 1
VLAN0001
Spanning tree enabled protocol rstp
Root ID Priority 1
Address 0016.9dba.e280
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 1 (priority 0 sys-id-ext 1)
Address 0016.9dba.e280
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa2/0/1 Desg FWD 19 128.55 P2p
Fa2/0/2 Desg FWD 19 128.56 P2p
Fa2/0/3 Desg FWD 19 128.57 P2p
Fa2/0/4 Desg FWD 19 128.58 P2p
Fa2/0/5 Desg FWD 19 128.59 P2p
Fa2/0/6 Desg FWD 19 128.60 P2p
Fa2/0/7 Desg FWD 19 128.61 P2p
Fa2/0/8 Desg FWD 19 128.62 P2p
c3750-ts37#conf t
Enter configuration commands, one per line. End with CNTL/Z.
c3750-ts37(config)#span vlan 1 for
c3750-ts37(config)#span vlan 1 forward-time 12
c3750-ts37(config)#^Z
c3750-ts37#sh span vlan 1
VLAN0001
Spanning tree enabled protocol rstp
Root ID Priority 1
Address 0016.9dba.e280
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 12 sec
Bridge ID Priority 1 (priority 0 sys-id-ext 1)
Address 0016.9dba.e280
Hello Time 2 sec Max Age 20 sec Forward Delay 12 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa2/0/1 Desg FWD 19 128.55 P2p
Fa2/0/2 Desg FWD 19 128.56 P2p
Fa2/0/3 Desg FWD 19 128.57 P2p
Fa2/0/4 Desg FWD 19 128.58 P2p
Fa2/0/5 Desg FWD 19 128.59 P2p
Fa2/0/6 Desg FWD 19 128.60 P2p
Fa2/0/7 Desg FWD 19 128.61 P2p
Fa2/0/8 Desg FWD 19 128.62 P2p
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