From: Victor Cappuccio (cvictor@protokolgroup.com)
Date: Thu Aug 31 2006 - 15:08:35 ART
Hi Friend Bajo,
When you apply the macro spanning-tree vlan 1 root primary, it going to
generate for you something in the configuration like spanning-tree vlan 16
priority 24576
So for example if you set the priority manually at Sw2
Rack3Sw2(config)#spanning-tree vlan 1 priority 4096
Rack3Sw2(config)#
BB1-TS#7
[Resuming connection 7 to sw1 ... ]
Rack3Sw1(config)#do show spanning-tree vlan 1
VLAN0001
Spanning tree enabled protocol ieee
Root ID Priority 4097
Address 000e.84d0.d380
Cost 19
Port 15 (FastEthernet0/15)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)
Address 000b.5f55.f800
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 600
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- --------
--------------------------------
Fa0/15 Root FWD 19 128.15 P2p
Now If I set the macro at the switch the priority should be reduced
Rack3Sw1(config)# spanning-tree vlan 1 root primary
Rack3Sw1(config)#do show run | in prio
spanning-tree vlan 1 priority 4096
ip ospf priority 255
ip ospf priority 255
Rack3Sw1(config)#do show spann vlan 1
VLAN0001
Spanning tree enabled protocol ieee
Root ID Priority 4097
Address 000b.5f55.f800
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 4097 (priority 4096 sys-id-ext 1)
Address 000b.5f55.f800
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 15
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- --------
--------------------------------
Fa0/15 Desg FWD 19 128.15 P2p
HTH
Victor.-
-----Mensaje original-----
De: nobody@groupstudy.com [mailto:nobody@groupstudy.com] En nombre de
sabrina pittarel
Enviado el: Jueves, 31 de Agosto de 2006 01:36 p.m.
Para: Bajo; Cisco certification
Asunto: Re: spanning-tree vla XX root and "sh run"
No,
spanning-tree vla XX root is a macro command.
It sets the local bridge priority to be less than the current lowest
priority in your switched network ("how much" lower is well defined, but I
don't have the rule on the top of my mind ), essentially it kicks away your
current root bridge.
BUT if you later add another switch with an even lower priority then the
new bridge will become root.
Leaving the "spanning-tree vla XX root" in the running config gives you the
wrong idea that this switch will be root no matter what. That's not the case
Sabrina
----- Original Message ----
From: Bajo <bajoalex@gmail.com>
To: Cisco certification <ccielab@groupstudy.com>
Sent: Thursday, August 31, 2006 9:08:31 AM
Subject: spanning-tree vla XX root and "sh run"
Hi GS,
Is it an IOS bug that the "sh run | in spannin" will NOT show the
spanning-tree vlan XXXX root config?
I know I can check if the config works by doing "sh spann vla XXXX"
Check this out:
CAT1) conf t
CAT1(config)#spann vl 16 root pri
CAT1(config)#end
CAT1#sh run | in spann
spanning-tree mode pvst
spanning-tree extend system-id
spanning-tree vlan 16 priority 24576
spanning-tree vlan 16 port-priority 32
spanning-tree vlan 16 port-priority 16
CAT1#sh ver
Cisco Internetwork Operating System Software
IOS (tm) C3550 Software (C3550-I5Q3L2-M), Version 12.1(20)EA1a, RELEASE
SOFTWARE (fc1)
-- Kind Regards,Bajo
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