From: Mihai Petcu (mpetcu2004@yahoo.com)
Date: Mon May 02 2005 - 17:40:18 GMT-3
Hi,
I subscribe to Galdston's test results, one should adjust ONLY the forward delay timer in order to achieve this task's goal -> go to forward state in 16 seconds.
Taking further Gladston's test, I used "debug spanning-tree events" command on a 3550 and here are the results :
SW1#debug spanning-tree events
Spanning Tree event debugging is on
SW1#
SW1#show span
SW1#show spanning-tree vla
SW1#show spanning-tree vlan 263
VLAN0263
Spanning tree enabled protocol ieee
Root ID Priority 33031
Address 000e.3811.1a80
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 33031 (priority 32768 sys-id-ext 263)
Address 000e.3811.1a80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/2 Desg FWD 100 128.2 Shr
Fa0/13 Desg FWD 19 128.13 P2p
SW1#c
Enter configuration commands, one per line. End with CNTL/Z.
SW1(config)#int
SW1(config)#interface f0/2
SW1(config-if)#sh
SW1(config-if)#
.May 2 23:37:13.132: %LINK-5-CHANGED: Interface FastEthernet0/2, changed state to
administratively down
administratively down
/2, changed state to down
SW1(config-if)#
SW1(config-if)#
SW1(config-if)#
SW1(config-if)#
SW1(config-if)#
SW1(config-if)#no sh
SW1(config-if)#
.May 2 23:37:21.624: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to d
own
00:19:50: set portid: VLAN0263 Fa0/2: new port id 8002
00:19:50: STP: VLAN0263 Fa0/2 -> listening
.May 2 23:37:23.672: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to u
p
.May 2 23:37:24.672: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0
/2, changed state to up
SW1(config-if)#
00:20:05: STP: VLAN0263 Fa0/2 -> learning
00:20:20: STP: VLAN0263 Fa0/2 -> forwarding
SW1(config-if)#
SW1(config-if)#^Z
SW1#
Look at STP state going from blocking to forwarding in 30 seconds (2 x 15 sec forward delay). This means that max_age is not involved at all.
HTH,
Mihai
gladston@br.ibm.com wrote:
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 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 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 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
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 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 LRN 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
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