From: Prashanth (prashanthcm@yahoo.com)
Date: Fri Jan 03 2003 - 17:35:08 GMT-3
Richard,
>Now I want to use the
> "spanning-tree vlan ...
> port-priority ..." commands to control which port on
> switch B to be in the
> block state. Where should I put the command
> "spanning-tree vlan ...
> port-priority ...", on switch A or on switch B, if A
> is root for all Vlans and
> all A ports are in forwarding state. Cisco never
> mentioned in the "3550
> configuration guide" that this command should be put
> on the upstream switch to
> influence downstream or put on the downstream
> directly.
the commands go on the trunk port of the downstream
switch (non-root or designated bridge)
I have not gone through the 3550 doc myself, I have
tried this on the 29xx/35xx XL/Cat 5k switches and it
works ... if it does not mention about the root switch
you might want to Submit a feedback to Cisco and see
what is their reply..
-prashanth-
--- ccieingroup@hotmail.com wrote:
> Hi Prashanth,
>
> Thanks for your reply. I have read the link you gave
> me. This example is the
> same as what I read in "Catalyst 3550 Multilayer
> Switch Software
> configuration Guide.pdf" Chapter 10-26 Configuring
> VLANs (Load Sharing Using
> STP) and Chapter 14-15 configuring STP( Configuring
> the port priority)."
>
> I just wonder why in this example, cisco didn't
> mention which switch is the
> root switch though it mentioned where to put the
> commands. So let's assume
> Switch A(or switch 1) is the root switch for all
> vlans, there are two parallel
> trunk connections between the switch A(switch 1) and
> switch B(or said switch 2
> in the real cisco example). Now I want to use the
> "spanning-tree vlan ...
> port-priority ..." commands to control which port on
> switch B to be in the
> block state. Where should I put the command
> "spanning-tree vlan ...
> port-priority ...", on switch A or on switch B, if A
> is root for all Vlans and
> all A ports are in forwarding state. Cisco never
> mentioned in the "3550
> configuration guide" that this command should be put
> on the upstream switch to
> influence downstream or put on the downstream
> directly.
> > Switch A (Root Bridge for all vlans)
> > 0/1| |0/2
> > 1/1| |1/2
> > Switch B.
>
> I also refer to the "CCIE Professional Development
> Cisco LAN Switching" Page
> 249: Port/VLAN Priority- "set spantree portvlanpri"
> can be used to load
> balance between back-to-back switches. This
> technique allows network
> administrators to modify port ID values(Port ID=Port
> priority + Port number)
> on upstream switches to influence forwarding and
> blocking decisions on
> neighboring downstream switches."
>
> Thanks,
> Richard
> ----- Original Message -----
> Wrom: DREXCAXZOWCO
> To: Richard Hanks ; ccielab@groupstudy.com
> Sent: Friday, January 03, 2003 2:13 AM
> Subject: Re: One question about 3550 Port
> Priority?
>
>
> Switch B
>
>
> if Switch A is the root bridge for all your VLANs
> (all ports in forwarding)
> and the only way to load-balance is by playing
> with
> the port priority on the downstream switch (B)
>
> say if you have 4 VLANS and Switch A is the Root
> for
> all the 4.... by default one of the trunk ports on
> Switch B will be in blocking state...
>
> you can modify the port priority on one one trunk
> port
> for two vlans to be in forwarding state and two in
> blocking state....similarly on the other so that
> each
> trunk port carries traffic from two VLANs... when
> one
> fails....one trunk carries all the traffic...
>
>
>
http://www.cisco.com/en/US/products/hw/switches/ps628/products_configuratio
> n_guide_chapter09186a008007e8c7.html#xtocid45
>
> -prashanth-
>
>
>
> --- Richard Hanks <ccieingroup@hotmail.com> wrote:
> > Hi Friends,
> >
> > I have a question here about the 3550 Port
> Priority.
> > Please refer to the
> >
> > "Catalyst 3550 Multilayer Switch Software
> > configuration Guide.pdf" Chapter
> > 10-26 Configuring VLANs (Load Sharing Using STP)
> and
> > Chapter 14-15 configuring
> > STP( Configuring the port priority).
> >
> > My question is if two 3550 connected by two
> trunk
> > links like this one.
> >
> > Switch A (Root Bridge)
> > 0/1| |0/2
> > 1/1| |1/2
> > Switch B.
> >
> > I want to use the "spanning-tree vlan 20
> > port-priority ..." to make the Switch
> > B's 1/1 in forwarding state for vlan 20 but 1/2
> in
> > the block state. Where
> > should I put the "spanning-tree vlan ..
> > port-priority" command on? I mean
> > whether on Switch A's port 0/1 and 0/2 or Switch
> B's
> > 1/1 and 1/2. I mean
> > whether the upstream switch or downstream switch
> > directly.
> >
> > I also refer to the "CCIE Professional
> Development
> > Cisco LAN Switching" Page
> > 249: Port/VLAN Priority- "set spantree
> portvlanpri"
> > can be used to load
> > balance between back-to-back switches. This
> > technique allows network
> > administrators to modify port ID values(Port
> ID=Port
> > priority + Port number)
> > on upstream switches to influence forwarding and
> > blocking decisions on
> > neighboring downstream switches."
> >
> > But I can't find any such description in the
> 3550
> > configuration guide. From
> > the example of page 10-26. Though it mentioned
> where
> > to put the commands on,
> > but it didn't mention which switch is the root.
> >
> > Appreciate for any help.
> > Rgds,
> > Richard
> > .
> >
>
>
This archive was generated by hypermail 2.1.4 : Sat Feb 01 2003 - 07:33:40 GMT-3