12-02-2010 09:05 AM - edited 03-06-2019 02:19 PM
Hi All,
I have a Cisco 3750 switch on which I am seeing the bridge priroty to be 49152. The default bridge priority has not been changed as seen from the running configuration given below -
!
version 12.2
no service pad
service timestamps debug uptime
service timestamps log datetime localtime
no service password-encryption
!
hostname Switch
!
enable password 7 XXXX
!
aaa new-model
vtp mode transparent
no ip subnet-zero
ip domain-name lehi.micron.com
ip name-server 10.192.88.4
ip name-server 10.192.88.6
!
!
no file verify auto
!
spanning-tree mode pvst
spanning-tree extend system-id
spanning-tree uplinkfast
!
vlan internal allocation policy ascending
!
vlan 10,100
!
!
interface Vlan1
no ip address
no ip route-cache
no ip mroute-cache
shutdown
!
interface Vlan100
description dbsn
ip address 10.192.100.9 255.255.254.0
no ip redirects
no ip route-cache
no ip mroute-cache
!
ip classless
no ip http server
!
!
Switch#sh spanning-tree vlan 10
VLAN0010
Spanning tree enabled protocol ieee
Root ID Priority 49162
Address 001e.7a50.e100
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 49162 (priority 49152 sys-id-ext 10)
Address 001e.7a50.e100
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Uplinkfast enabled
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Te1/0/1 Desg FWD 3002 128.29 P2p
Te1/0/2 Desg FWD 3002 128.30 P2p
Switch#sh sp
Switch#sh spanning-tree vl
Switch#sh spanning-tree vlan 100
VLAN0100
Spanning tree enabled protocol ieee
Root ID Priority 24676
Address 0022.9060.69c0
Cost 3002
Port 29 (TenGigabitEthernet1/0/1)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 49252 (priority 49152 sys-id-ext 100)
Address 001e.7a50.e100
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Uplinkfast enabled
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Te1/0/1 Root FWD 3002 128.29 P2p
Te1/0/2 Desg FWD 3002 128.30 P2p
Switch#sh ver
Cisco IOS Software, C3750E Software (C3750E-UNIVERSAL-M), Version 12.2(35)SE5, R
ELEASE SOFTWARE (fc1)
Copyright (c) 1986-2007 by Cisco Systems, Inc.
Compiled Thu 19-Jul-07 16:17 by nachen
Image text-base: 0x00003000, data-base: 0x01C00000
ROM: Bootstrap program is C3750E boot loader
BOOTLDR: C3750E Boot Loader (C3750E-HBOOT-M) Version 12.2(35r)SE1, RELEASE SOFTW
ARE (fc2)
Switch uptime is 1 week, 6 days, 18 hours, 43 minutes
System returned to ROM by power-on
System restarted at 15:11:11 MST Thu Nov 18 2010
System image file is "flash:c3750e-universal-mz.122-35.SE5/c3750e-universal-mz.1
22-35.SE5.bin"
License Level: ipservices Type: Permanent
Next reboot license Level: ipservices
cisco WS-C3750E-24TD (PowerPC405) processor (revision D0) with 245760K/16376K by
tes of memory.
Processor board ID CAT1147W09G
Last reset from power-on
2 Virtual Ethernet interfaces
1 FastEthernet interface
28 Gigabit Ethernet interfaces
2 Ten Gigabit Ethernet interfaces
The password-recovery mechanism is enabled.
512K bytes of flash-simulated non-volatile configuration memory.
Switch Ports Model SW Version SW Image
------ ----- ----- ---------- ----------
* 1 30 WS-C3750E-24TD 12.2(35)SE5 C3750E-UNIVERSAL-M
Configuration register is 0xF
I understand that the default priority is 32768+VLAN ID. Can any of check and see if I am missing something?
Thanks.
Solved! Go to Solution.
12-02-2010 11:52 AM
Hello,
The increased STP priority is caused by configuring the UplinkFast feature. Whenever you configure the UplinkFast, the switch priority will be raised automatically to 49152. Read more about the command and the UplinkFast feature here:
http://www.cisco.com/en/US/tech/tk389/tk621/technologies_tech_note09186a0080094641.shtml
Best regards,
Peter
12-02-2010 11:50 AM
Hi,
You're right default priority is 32768 but enabling uplinkfast will set priority to 49152.
Regards.
12-02-2010 11:54 AM
Hi,
Seems we've both "attacked" the same thread. Thanks for your reply!
Best regards,
Peter
12-02-2010 11:52 AM
Hello,
The increased STP priority is caused by configuring the UplinkFast feature. Whenever you configure the UplinkFast, the switch priority will be raised automatically to 49152. Read more about the command and the UplinkFast feature here:
http://www.cisco.com/en/US/tech/tk389/tk621/technologies_tech_note09186a0080094641.shtml
Best regards,
Peter
12-02-2010 11:55 AM
Hi Peter,
quicker than you on this one
Kind regards.
Alain.
12-06-2010 03:16 AM
Thanks all! That was helpful.
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