From: Timothy Snow (timsnow@cogeco.ca)
Date: Thu May 15 2003 - 02:15:15 GMT-3
Hey all..
I'm working on the Hello computer lab #1
cat1-3550 fa0/22 ----------- fa0/22 cat2-3550
fa0/23 ----------- fa0/23 cat2-3550
fa0/24 ----------- fa0/24 cat2-3550
Right now, port fa0/22 is the port that cat1-3550 uses to get to the
root for vlan14, which is cat2-3550. (see below)
at1-3550#sh span vlan 14
VLAN0014
Spanning tree enabled protocol ieee
Root ID Priority 24590
Address 0008.217a.4c80
Cost 19
Port 22 (FastEthernet0/22)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 28686 (priority 28672 sys-id-ext 14)
Address 0009.e86c.8c80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Port ID Designated
Port ID
Name Prio.Nbr Cost Sts Cost Bridge ID
Prio.Nbr
---------------- -------- --------- --- --------- --------------------
--------
Fa0/22 128.22 19 FWD 0 24590 0008.217a.4c80
128.22
Fa0/23 128.23 19 BLK 0 24590 0008.217a.4c80
128.23
Fa0/24 128.24 19 BLK 0 24590 0008.217a.4c80
128.24
After reading page 14-15 of the config guide, it says that regular port
priority "spanning-tree port-priority X" is used for access ports and
vlan port-priority "spanning-ree vlan Y port-priority X" is used for
trunk ports (which this is)
As it stands, the priority is equal, the cost is equal, so it goes to
the lowest interface number (see FWD above)
I tried to adjust using the vlan port-priority to the lowest number
(meaning highest priority) and the display shows it but fa0/24 doesn't
become FWD'ing like I expected. (see outout)
cat1-3550(config-if)#spanning-tree vlan 14 port-priority 1
cat1-3550(config-if)#
cat1-3550#
May 15 02:07:52.059: %SYS-5-CONFIG_I: Configured from console by console
cat1-3550#sh span vlan 14
VLAN0014
Spanning tree enabled protocol ieee
Root ID Priority 24590
Address 0008.217a.4c80
Cost 19
Port 22 (FastEthernet0/22)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 28686 (priority 28672 sys-id-ext 14)
Address 0009.e86c.8c80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Port ID Designated
Port ID
Name Prio.Nbr Cost Sts Cost Bridge ID
Prio.Nbr
---------------- -------- --------- --- --------- --------------------
--------
Fa0/22 128.22 19 FWD 0 24590 0008.217a.4c80
128.22
Fa0/23 128.23 19 BLK 0 24590 0008.217a.4c80
128.23
Fa0/24 1.24 19 BLK 0 24590 0008.217a.4c80
128.24
So it's a vlan port-pri is 1 (trunk port) as opposed to "regular
port-priority" but it hasn't becoming FWD'ing. So i'll go remove that
vlan port-pri, and changed the COST to something lower.
cat1-3550(config-if)#spanning-tree vlan 14 cost 5
cat1-3550(config-if)#
May 15 02:10:04.695: %SYS-5-CONFIG_I: Configured from console by console
cat1-3550#sh span vlan 14
VLAN0014
Spanning tree enabled protocol ieee
Root ID Priority 24590
Address 0008.217a.4c80
Cost 5
Port 24 (FastEthernet0/24)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 28686 (priority 28672 sys-id-ext 14)
Address 0009.e86c.8c80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 15
Interface Port ID Designated
Port ID
Name Prio.Nbr Cost Sts Cost Bridge ID
Prio.Nbr
---------------- -------- --------- --- --------- --------------------
--------
Fa0/22 128.22 19 BLK 0 24590 0008.217a.4c80
128.22
Fa0/23 128.23 19 BLK 0 24590 0008.217a.4c80
128.23
Fa0/24 128.24 5 FWD 0 24590 0008.217a.4c80
128.24
Am I doing something wrong here? I thought I had the understanding that
the selection goes as follows. COST, Port-pri, interface number
(tie-breaker) but it appears that no matter what I adjust the vlan
port-pri to it's never looked at even if cost was the same. I lower the
cost and the port I want to be FWD'ing is. What gives?
Any help would be appreciated...
Tim
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