MAC address on Root bridge

enrenraku · ‎05-25-2005

please help me out on this,

when i do " show span-tree vlan 9 " on IOS switch

it get the root switch MAC address.

how do i find this switch that carries this MAC address on my network, suppose i have a lots of switches.

Spanning tree enabled protocol ieee

Root ID Priority 32768

Address 0007.4f5d.b802

many thanks in advance

John

amit-singh · ‎05-25-2005

Hi John,

The only way you can do it is by running "show version "command and you will be able to see the mac address of the switch.

*****************************************************

Cisco Internetwork Operating System Software

IOS (tm) C3500XL Software (C3500XL-C3H2S-M), Version 12

RE (fc1)

Compiled Fri 28-May-04 09:19 by antonino

Image text-base: 0x00003000, data-base: 0x00351754

ROM: Bootstrap program is C3500XL boot loader

C48-BS6 uptime is 48 weeks, 4 days, 12 hours, 33 minute

System returned to ROM by reload

System restarted at 04:30:30 IST Sat Jun 19 2004

System image file is "flash:c3500xl-c3h2s-mz.120-5.WC10

cisco WS-C3524-PWR-XL (PowerPC403) processor (revision

tes of memory.

Processor board ID CAT0608Z041, with hardware revision

Last reset from warm-reset

Processor is running Enterprise Edition Software

Cluster command switch capable

Cluster member switch capable

24 FastEthernet/IEEE 802.3 interface(s)

2 Gigabit Ethernet/IEEE 802.3 interface(s)

32K bytes of flash-simulated non-volatile configuration

Base ethernet MAC Address: 00:08:E3:C7:87:00##This is the MAC address ###.

Motherboard assembly number: 73-4033-08

Power supply part number: 34-0968-02

Motherboard serial number: CAT0608020T

Power supply serial number: LIT06060353

Model revision number: G0

Motherboard revision number: A0

Model number: WS-C3524-PWR-XL-EN

Daughterboard serial number: CAT060801PY

System serial number: CAT0608Z041

Configuration register is 0xF

HTH,

-amit singh

Kevin Dorrell · ‎05-25-2005

The best way to do this is to trace it through the root ports.

Do a show span-tree vlan 9 and make a note of the designated root port of the current switch. Go to the switch that is connected to that port. (If you are not sure which it is, the show cdp neighbor should tell you.)

Repeat, and continue this iteration until you come to the root switch. You can tell when you have arrived at the root, 'cos the designated root will be the same as the BID.

Once you have found it, decide whether it is a good choilce for the root, and fix it by lowering its priority. Then you will know where you stand in the future, and adding switches will no longer disrupt the VLAN.

Hope this helps.

Kevin Dorrell

Luxembourg