[cisco-voip] Switch replacement causes one-way audio?

David Sullivan David.Sullivan at barnet.ac.uk
Thu Feb 12 10:12:36 EST 2009

cisco-voip-bounces at puck.nether.net wrote:
> This past weekend our network team replaced some aging 4006s
> with 3750 stacks.  Since then we've had users complaining
> that callers on the far end cannot hear them.  Our first
> thought was to hard code the switch-port to 100/full (we're
> using 7960Gs) - and that didn't seem to help.

Never ever do this unless you hardcode both ends. A better idea is not
to do it all, devices get moved around and it will just lead to aggro
for someone later on. Hard setting speed and duplex probably causes more
problems than it solves these days.

> Does anyone have any ideas on what we could check before opening a
> TAC case tomorrow? 

Arp inspection or dhcp snooping on the 3750 gone awry? Try turning those
off and seeing if this resolves it, otherwise it could be an ACL
somewhere. Are calls between two phones on the same subnet ok?

David Sullivan
IT Services Systems Team
Barnet College 
This communication may contain privileged or confidential information which
is for the exclusive use of the intended recipient.  If you are not the
intended recipient, please note that you may not distribute or use this
communication or the information it contains.  If this e-mail has reached you
in error, please delete it and any attachment.

Internet communications are not secure and Barnet College does not accept
legal responsibility for the content of this message.  Any views or opinions
expressed are those of the author and not necessarily those of Barnet College.

Please note that Barnet college reserves the right to monitor the
source/destinations of all incoming or outgoing e-mail communications.

More information about the cisco-voip mailing list