[cisco-voip] Re: Spanning-tree Topology Change with IP Phones

[michaelreilly at nc.rr.com]

Kevin no need to separate check out below

interface FastEthernet0/1
 switchport trunk encapsulation dot1q
 switchport trunk native vlan 50
 switchport mode trunk
 switchport voice vlan 105
 spanning-tree portfast

----- Original Message -----
From: kevin knowlen <kevin.knowlen at gmail.com>
Date: Monday, November 15, 2004 9:22 am
Subject: [cisco-voip] Re: Spanning-tree Topology Change with IP Phones

> All,
> 
> 
> We have narrowed the problem down to 3500 switches (3524 and 
> 3512). 
> The situation is that we want to hang computers off of the IP Phone's
> PC port.  We have some 3524s in our network that we have been trying
> to do this with. When we configure the interface for switchport voice
> vlan XXX and switch port access vlan XXX. It doesn't work, the phone
> is stuck configuring IP.  It only works if you put switchport mode
> trunk on the interface.  When you do this it creates a STP topoloy
> change when you plug in or unplug an IP phone into the port.  We have
> tried all suggestions and all end up with the same result.  We are now
> considering the separation of phones and computers on 3500 switches
> where each have a physically separate port.
> 
> Is this what to expect on 3500 switches, or is there a work 
> around? 
> 
> 
> On Sun, 14 Nov 2004 20:44:40 -0500, Greg Arthmann
> <garthmann at data-corporation.com> wrote:
> >  
> > 
> > Kevin,
> >  Spanning-tree portfast doesn't prevent a port from particpating in
> > spanning-tree. What it does is signifcantly speed up the time it 
> takes a
> > port to move from blocking to forwarding.
> >  So BPDU's will still be sent and recieved. Portfast should only 
> be enabled
> > on a port connected to a PC or Server, not to another switch or 
> hub. Do you
> > have any phsyical loops in your network? Plugging in an IP Phone 
> shouldn't> cause your spanning-tree topology to change.
> >  
> >  Greg Arthmann
> >  Network Consultant
> >  CCNP,CCDP,CIPT
> >  Phone (786)554-2958
> >  www.data-corporation.com
> >  "Cisco Advanced Technology Partner"
> >  
> >  
> >  
> >  
> >  Date: Sat, 13 Nov 2004 10:25:42 +0300
> >  From: kevin knowlen <kevin.knowlen at gmail.com>
> >  Subject: [cisco-voip] Switch STP problem
> >  To: cisco-voip at puck.nether.net
> >  Message-ID: <8a8dccee0411122325680c7877 at mail.gmail.com>
> >  Content-Type: text/plain; charset=US-ASCII
> >  
> >  All,
> >  
> >  We have a problem with STP convergance.  We have a gigabit switched
> >  network, using a combination of 3500, 3550, 3560 switches.  We 
> use the
> >  below switch config.  According to Cisco documentation, 
> spanning-tree
> >  port fast is susposed to prevent the voice vlan port from
> >  participating in STP.  We even put bpduguard on the port.  We 
> tested>  the config and switches up stream still re-converge all 
> the way up to
> >  the CORE, when a IP phone is unplugged.
> >  
> >  Interface fa 0/2
> >  switchport mode trunk
> >  switchport trunk encapsulation dot1q
> >  switchport voice vlan XXX
> >  switchport trunk native vlan XX
> >  spanning-tree portfast
> >  spanning-tree bpduguard enable
> >  
> >  
> >  --
> >  1LT Knowlen, Kevin
> >  
> >  
> >  
> >  
> >  
> >  
> >  
> 
> 
> -- 
> 1LT Knowlen, Kevin
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