From: Lou Ioanni (louisccie_r_s@yahoo.com)
Date: Tue Feb 20 2007 - 19:28:04 ART
Right. You do not deduct vlan number from default to get priority. What confused you is the way they map vlans to priorities ex. 2-32768, 3-4094, etc
I never heard of such formula. I will be very surprised if there is any.
Loizos Y.
CCIE#10702 R & S
Gobind <gobind@inbox.com> wrote:
So in no case this is true,right?:-
Bridge priority = Default bridge priority - Vlan Number
I heard it in CBT was got confused!
> -----Original Message-----
> From: louisccie_r_s@yahoo.com
> Sent: Tue, 20 Feb 2007 11:21:11 -0800 (PST)
> To: gobind@inbox.com, ccielab@groupstudy.com
> Subject: Re: Bridge Priority
>
> Yes each vlan has its own root depending on the priority. If priorities
> are the same then it uses the mac to select the root. Each vlan and
> priorities are combined to create a unique ID. Check the floowing link
> for a siminlar question and answers:
>
> http://www.velocityreviews.com/forums/t37177-bridge-priority-and-sysidext-number.html
>
> Gobind wrote: If the sys-id-ext usually correlates
> to Vlan Number,it means like for Vlan Number 1 the sys-id-ext would be
> 1,right? it is taken automatically or manually? I am confused about the
> part that the If in a switch every Vlan has its own priority then when
> the Root Election occurs,does it occurs to every Vlan,lets say there are
> 3 Vlans and what if it have different Priority then is it also possible
> that on Switch would be Root Bridge for 1 Vlan and not other two(due to
> higher Priority)?
>
>
> -----Original Message-----
> From: louisccie_r_s@yahoo.com
> Sent: Tue, 20 Feb 2007 10:59:29 -0800 (PST)
> To: gobind@inbox.com, ccielab@groupstudy.com
> Subject: Re: Bridge Priority
>
>
> I am not sure if you refering to a specific lab exercise, but in real
> environments you can select which switch you want to be the Root Bridge
> for specific vlans by lowering the priority from the default 32768. The
> lower the priority the more prefered to be the root (example 32000). If
> you want to FORCE a specific switch to be the root then you set priority
> 0. For example:
>
> spanning-tree vlan 10-14 priority 0 (This will set this switch to be the
> root for vlans 10,11,12,13,14)
>
> You can set a different root bridge for each group of vlans for load
> balancing. You can direct certain vlans traffic through one distribution
> switch and other vlans through the other distribution reduntant switch
> for load balancing L2 traffic.
>
> Usually is good to set the L3 distribution switches as the Root bridges
> for the vlans attached to the access layer switches attached to it.
>
> Thanks,
>
> Loizos Y.
> CCIE#10702 R & S
>
>
>
> Gobind wrote: Hi Guys,
>
> I have some confusion wiht the Bridge Priority.In Some CBTs I am getting
> to hear that:-
>
> Bridge Priority is Default Priority(32768) - Vlan Number
>
> I asked my friend,he said Default Priority is Default Priority + Vlan
> Number
>
> In one Cisco Dumentation it is written:-
>
> "Each VLAN on each network device has a unique 64-bit bridge ID
> consisting of a bridge priority value, an extended system ID, and an STP
> MAC address allocation"
>
> Source:- http://www.cisco.com/en/U
> S/products/hw/switches/ps708/products_configuration_guide_chapter09186a008016
> 0a5b.html#wp1040218
>
> I am really confused(maybe I am getting it wrong) what Priority(in STP
> is),also I am not getting if the Priority is Default priority + Vlan
> Number or - Vlan Number then what Vlan Number is it refering to? I mean
> the Trunk belongs to every Vlan then which Vlan Number it takes while
> making the election.(when it sends BPDU i.e.)
>
> Gobind
>
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This archive was generated by hypermail 2.1.4 : Thu Mar 01 2007 - 07:38:47 ART