[cisco-voip] Switch Hanging off Phone

[Truelove_John]

Like Mike suggested.

We use spanning-tree bpduguard enable on all of our access ports.
I also have ip dhcp snooping enabled on all 3560/3750 in our network and only
trust the uplinks and valid ports.


Just a standard part of my switch configs, can save you some
headaches in the future because of end user cabling errors or rouge DHCP servers.

I once had a cleaning person wanting to move the CAT5 cable out of the way connect
the other end of the cable back to the second port in the wall jack, flattened that network.


hth
John Truelove




-----Original Message-----
From: cisco-voip-bounces at puck.nether.net on behalf of Mike Louis
Sent: Sun 9/21/2008 11:14 AM
To: Todd Franklin; Mike Brooks
Cc: cisco-voip at puck.nether.net
Subject: Re: [cisco-voip] Switch Hanging off Phone
 
Why is there no priority out command on this voice port. That could cause issues if you had a broadcast storm on the port from a loop on the network

________________________________
From: Todd Franklin <toddnh65 at gmail.com>
Sent: Saturday, September 20, 2008 3:48 PM
To: Mike Brooks <2xccie2b at gmail.com>
Cc: cisco-voip at puck.nether.net <cisco-voip at puck.nether.net>
Subject: Re: [cisco-voip] Switch Hanging off Phone

Thanks Mike.  The config of the switchport:

interface FastEthernet0/4
 switchport trunk encapsulation dot1q
 switchport mode dynamic desirable
 switchport voice vlan 6
 srr-queue bandwidth share 10 10 60 20
 srr-queue bandwidth shape  10  0  0  0
 mls qos trust device cisco-phone
 mls qos trust cos
 auto qos voip cisco-phone
 spanning-tree portfast

It really screwed around with the phones.  The data stayed ok.

He came off from the switchport, into the 7940.  From there into the Linksys (which has a built in 4 port switch) and one of those ports he had plugged into his PC.

What do you think?

Todd

On Sat, Sep 20, 2008 at 3:38 PM, Mike Brooks <2xccie2b at gmail.com<mailto:2xccie2b at gmail.com>> wrote:
What was the configuration of the switchport ?  Also was the data vlan
affected at all or just devices on the voice vlan ?  A common issue we
have seen with hubs plugged in is them getting mis-cabled by the
enduser and getting looped up causing major issues on the network.  I
do not believe the linksys devices send BPDUs.  If it was a cabling
issue on the linksys ..then enabling bpduguard on the port will
errdisable the port..because the port will receive its own bpdu if the
linksys is miscabled.

Also, the linksys could have been acting as a rouge dhcp server.  Not
knowing how your network is set up or the symptoms you were
experiencing it would be hard to tell.

Just a few guesses ;-)

hth,

Mike Brooks
CCIE# 16027 (R&S)

On Sat, Sep 20, 2008 at 3:10 PM, Todd Franklin <toddnh65 at gmail.com<mailto:toddnh65 at gmail.com>> wrote:
> Phone system went "kerflunk" yesterday.  Found a 7940 with a Linksysy
> wireless router plugged into the PC port of the phone.  Could that have done
> it?  I seem to remember one VAR telling me this was a grand way to take an
> IPT network down.
>
> Also, is there any configuration I can add to the 3560s that would
> "disallow" this configuration?
>
> Thank you!
>
> Todd
> _______________________________________________
> cisco-voip mailing list
> cisco-voip at puck.nether.net<mailto:cisco-voip at puck.nether.net>
> https://puck.nether.net/mailman/listinfo/cisco-voip
>
>


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