Forward Delay

From: gladston@br.ibm.com
Date: Mon May 02 2005 - 15:35:43 GMT-3

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Hi,

The quoted discussion was about setting the time for a port go to forward state.

Considering the CCIE lab is not about Best Practices, why should we set the maxage time? (if the task ask us to adjust the STP timers so a port take 16 seconds to go to forward state)

The test that follows shows there is no difference on the time the port takes to go to forward state changing MAXAGE. (the task considers access port)

===============
quoted

Hello,

you have to change the forward and maxage timers. STP by default uses a
maxage timer of 20 seconds and a forward timer of 15 second (x2 =30). To
achieve 16 seconds, you have to configure:

spanning-tree vlan x forward-time 5 max-age 6

Regards,

GP
================

CAT2(config)#int fa 0/1
CAT2(config-if)#sh
CAT2(config)#int fa 0/1
CAT2(config-if)#do sh clock
03:22:25.555 UTC Mon May 2 2005
CAT2(config-if)#no sh
CAT2(config-if)#^Z
CAT2#sh spanning-tree int fa 0/1

Vlan Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
VLAN0034 Desg LIS 19 128.1 P2p
CAT2#sh spanning-tree int fa 0/1

Vlan Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
VLAN0034 Desg LRN 19 128.1 P2p
CAT2#sh spanning-tree int fa 0/1

Vlan Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
VLAN0034 Desg FWD 19 128.1 P2p
CAT2#sh clock
03:22:40.467 UTC Mon May 2 2005

CAT2#sh spanning-tree vlan 34

VLAN0034
  Spanning tree enabled protocol ieee
  Root ID Priority 32802
             Address 000c.cebd.8000
             This bridge is the root
             Hello Time 2 sec Max Age 20 sec Forward Delay 4 sec

  Bridge ID Priority 32802 (priority 32768 sys-id-ext 34)
             Address 000c.cebd.8000
             Hello Time 2 sec Max Age 20 sec Forward Delay 4 sec
             Aging Time 300

Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/1 Desg FWD 19 128.1 P2p
Fa0/2 Desg FWD 19 128.2 Edge P2p
Fa0/47 Desg FWD 19 128.47 P2p
Fa0/48 Desg FWD 19 128.48 P2p
Gi0/1 Desg FWD 4 128.49 P2p
Gi0/2 Desg FWD 4 128.50 P2p

CAT2(config)#spanning-tree vlan 34 max-age 6
CAT2(config)#
CAT2(config)#int fa 0/1
CAT2(config-if)#do sh clock
03:23:46.007 UTC Mon May 2 2005
CAT2(config-if)#no sh
CAT2(config-if)#^Z
CAT2#sh spanning-tree int fa 0/1

Vlan Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
VLAN0034 Desg LRN 19 128.1 P2p
CAT2#sh spanning-tree int fa 0/1

Vlan Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
VLAN0034 Desg FWD 19 128.1 P2p
CAT2#sh clock
03:23:59.939 UTC Mon May 2 2005
CAT2#sh spanning-tree vlan 34

VLAN0034
  Spanning tree enabled protocol ieee
  Root ID Priority 32802
             Address 000c.cebd.8000
             This bridge is the root
             Hello Time 2 sec Max Age 6 sec Forward Delay 4 sec

  Bridge ID Priority 32802 (priority 32768 sys-id-ext 34)
             Address 000c.cebd.8000
             Hello Time 2 sec Max Age 6 sec Forward Delay 4 sec
             Aging Time 300

CAT2(config)#spanning-tree vlan 34 max-age 40
CAT2(config)#int fa 0/1
CAT2(config-if)#do sh clock
03:24:57.419 UTC Mon May 2 2005
CAT2(config-if)#no sh
CAT2(config-if)#^Z
CAT2#sh spanning-tree int fa 0/1

Vlan Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
VLAN0034 Desg LIS 19 128.1 P2p
CAT2#sh spanning-tree int fa 0/1

Vlan Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
VLAN0034 Desg LRN 19 128.1 P2p
CAT2#sh spanning-tree int fa 0/1

Vlan Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
VLAN0034 Desg FWD 19 128.1 P2p
CAT2#sh clock
03:25:13.483 UTC Mon May 2 2005

Next message: Etchings, Jay: "Accomadations"
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Next in thread: Mihai Petcu: "Re: Forward Delay"
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