From: Digital Yemeni (digital.yemeni@gmail.com)
Date: Sun Mar 25 2007 - 08:59:14 ART
The "spanning-tree mst xx root primary" is just a macro for the command
"spanning-tree priority x" ;-)
On 3/25/07, Marut S@MS@DCTH-BKK <Marut.s@datacraft-asia.com> wrote:
>
> Hi Group,
>
>
>
> I have found something interesting about this topic.
> Previously I understand that spantree mst xx root primary will make
> switch to be root no matter what priority value of the other switches in
> the domain. But from my testing result. I found that if other switch was
> setup as priority 0. spanning-tree mst xx root primary is useless.
>
>
>
> I have switches 1 & 3. Both run MST.
>
>
>
> ------------------------------------------------------------------------
> -------------------------------------------------------
>
> SW1#sh span mst 11
>
>
>
> ##### MST11 vlans mapped: 11
>
> Bridge address 0016.c859.7980 priority 32779 (32768 sysid
> 11) -------> SW1
>
> Root address 000c.8555.7880 priority 32779 (32768 sysid
> 11) --------> SW3
>
> SW1#sh run | i span
>
> spanning-tree mode mst
>
> spanning-tree extend system-id
>
> spanning-tree mst configuration
>
>
>
> SW3(config)#do sh span mst 11
>
>
>
> ##### MST11 vlans mapped: 11
>
> Bridge address 000c.8555.7880 priority 32779 (32768 sysid
> 11)
>
> Root this switch for MST11
>
>
>
> ------------------------------------------------------------------------
> -------------------------------------------------------
>
>
>
> I want sw1 to be root switch
>
> SW1(config)#span mst 11 root prim
>
> SW1(config)#do sh span mst 11
>
>
>
> ##### MST11 vlans mapped: 11
>
> Bridge address 0016.c859.7980 priority 24587 (24576 sysid
> 11)
>
> Root this switch for MST11
>
>
>
> SW3(config)#do sh span mst 11
>
>
>
> ##### MST11 vlans mapped: 11
>
> Bridge address 000c.8555.7880 priority 32779 (32768 sysid
> 11)
>
> Root address 0016.c859.7980 priority 24587 (24576 sysid
> 11)
>
>
>
> ------------------------------------------------------------------------
> ----------------------------------------------------------
>
>
>
> Then I want to test if I setup priority for mst 11 at sw3 to be 0. Will
> sw1 still adjust itself to be root ?
>
>
>
> ANSWER IS NO
>
>
>
> SW3(config)#span mst 11 pri 0
>
> SW3(config)#do sh span mst 11
>
>
>
> ##### MST11 vlans mapped: 11
>
> Bridge address 000c.8555.7880 priority 11 (0 sysid 11)
>
> Root this switch for MST11
>
>
>
>
>
> SW1(config)#do sh span mst 11
>
>
>
> ##### MST11 vlans mapped: 11
>
> Bridge address 0016.c859.7980 priority 24587 (24576 sysid
> 11)
>
> Root address 000c.8555.7880 priority 11 (0 sysid 11)
>
>
>
> SWITCH 1 NOT ADJUST ITSELF TO BE ROOT.
>
> ------------------------------------------------------------------------
> -------------------------------------------------------------
>
>
>
> THE CONCLUSION IS : if you asked to setup the switch to have best chance
> to be the root switch. Don't use spanning-tree mst xx root primary. But
> use spanning-tree mst xx priority 0 instead. (Try setup priority 0 at
> sw1 first. Sw3 won't allow me to configure root primary command.). Seem
> like spanning-tree mst xx root primary will adjust to the lowest value
> at 4096 and no more ( Adjust only one time you enter this command. In
> the show run you will see it as spanning-tree mst xx priority 4096..
> http://www.cisco.com/univercd/cc/td/doc/product/lan/cat3560/12225see/cr/
> cli3.htm#wp1946716
>
>
>
>
>
> Anyway if both switch is setup as priority 0. tie-break is
> mac-address. How could I forced mac-address of bridge-id ?
>
>
>
>
>
> Best Regards,
>
> Maruto
>
>
>
>
>
> -----Original Message-----
> From: William Walla [mailto:wwalla@gmail.com]
> Sent: Sunday, 25 March, 2007 2:26 AM
> To: Marut S@MS@DCTH-BKK
> Subject: Re: Ask for help : Best chance to set the switch to be root
>
>
>
> spantree vlan XX priority root
>
> William Walla
>
> 713-252-6203
>
> -----Original Message-----
>
> From: "Marut S@MS@DCTH-BKK" <Marut.s@datacraft-asia.com>
>
> Date: Saturday, Mar 24, 2007 2:08 pm
>
> Subject: Ask for help : Best chance to set the switch to be root
>
>
>
> Hi group,
>
>
>
> I have a question about best chance for set up the switch to
> be
>
> the root switch. Spanning-tree vlan xx priority 0 command that should be
> used.
>
>
>
> But if other switch has been setup priority = 0 too. Tie
> break
>
> is mac-address.
>
> Question is how could I setup mac-address for bridge-id ?
>
>
>
>
>
> Regards,
>
> Maruto
>
>
>
>
>
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-- Best Regards! Digital, CCIE# to be assigned by Cisco when it collects enough $$ out of me! :p
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