From: Richard Hanks (ccieingroup@hotmail.com)
Date: Sat Jan 04 2003 - 14:08:50 GMT-3
Hello Prashanth,
You said you ever test this command on Cat 5000 switch and the "set spantree
portvlanpri" command should be put on the downstream switch. I also asked this
question to Chuck Church and got this helpful link about this issue. The
detailed description are different from your test result. After you read it,
may we talk about this issue further. Now I just wonder that whether on 3550,
the "spanning-tree vlan .. port-pri .."comannd is the same as on the 5000's
"set spantree portvlanpri command", which is definitely should be put on the
upstream switch to influence the downstream switch's decision about which port
should be blocked and which one should be in forwarding.
"http://www.cisco.com/en/US/tech/tk389/tk689/technologies_tech_note09186a0080
0ae96a.shtml"
Thanks,
Richard
----- Original Message -----
From: Richard Hanks
To: Prashanth
Sent: Friday, January 03, 2003 9:48 PM
Subject: Re: One question about 3550 Port Priority?
Hi Prashanth,
Thank you very much for your reply!
Rgds,
Richard
----- Original Message -----
From: Prashanth
To: ccieingroup@hotmail.com ; ccielab@groupstudy.com
Sent: Friday, January 03, 2003 3:35 PM
Subject: Re: One question about 3550 Port Priority?
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_configurat
io
> 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
> > .
> >
>
>
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