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How do I identify which IP Phone that my laptop is connected with?

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This document was generated from CDN thread

Created by: Ramesh Singaraj on 26-10-2009 12:48:08 PM
Hi,
 
I have a requirement to identify the IP Phone details on which my laptop n/w cable is connected.
Once I identify the IP phone details I need to push the Extension Mobility profile of the logged-in user on that phone.
 
My thought for this is, a desktop client running on my laptop which could possibly identify the IP Phone details and use the pre-configured extension mobility credentials to push the profile to the phone.
 
Appriciate any help on "Identifying the IP Phone details" and "Pushing the extension mobility profile to the phone".
 
Regards,
Ramesh

Subject: RE: How do I identify which IP Phone that my laptop is connected with?
Replied by: David Staudt on 26-10-2009 07:09:47 PM
The indicated way to do this is for an application/service on the PC to listen on the network connection for Cisco Discovery Protol (CDP) packets (newer Cisco phones also support the open specification LLDP version.)  The app can then inspect these network packets to discover information about the connected Cisco device, such as whether it is a phone and what it's MAC and IP address are.
 
Note CDP (the only version supported on the 7940/60 and older generations) is a Cisco proprietary protocol - it does not have official documentation/SDK (or support for development.) 
 
In practice this whole concept turns out to be somewhat difficult to do, as you need to insert a hook in to the network stack (i.e. a kernel mode driver) and parse raw packets to get at the information.

Subject: RE: How do I identify which IP Phone that my laptop is connected with?
Replied by: Michel Shuqair on 22-01-2010 01:53:14 PM
Indeed it's not easy to detect the phone and I agree you need to use cdp or lldp.
 
There are some applications out there which already do what you want. If it's a matter of build or buy decision I would try http://www.spectra-ts.nl/default.asp?name=solutions&page=7 which is an application that our company built.
 
to build it yourself, you have to hook into the network card and parse the cdp and lldp packets at network level.
 
 

Subject: RE: How do I identify which IP Phone that my laptop is connected with?
Replied by: David Staudt on 22-01-2010 06:51:45 PM
Yep, it is not a trivial exercise to get the information - basically you will need to write a network device driver hook (and all the management that entails) to sniff out the CDP/LLDP packets and then parse the contents.  I did a bit of research awhile back that indicated winpcap (a generic library for sniffing network packets, with all the security considerations that entails) might be a good place to start.

Subject: RE: How do I identify which IP Phone that my laptop is connected with?
Replied by: Scott Brescia on 26-04-2011 06:54:01 PM
Yep, it is not a trivial exercise to get the information - basically you will need to write a network device driver hook (and all the management that entails) to sniff out the CDP/LLDP packets and then parse the contents.  I did a bit of research awhile back that indicated winpcap (a generic library for sniffing network packets, with all the security considerations that entails) might be a good place to start.

 
Yea, this doesn't exactly seem trivial/straight forward... I was looking into doing this myself, but the CDP/LLDP packets required only pop up every 60 seconds.
 
I found this tool http://www.hanewin.de/lldp-d.htm - 'haneWIN LLDP Agent for Windows' - which seems to be exactly what I want.  I pop open the software, and it shows me the info I need to know - what I want to know now is, how is this software polling for this?  I was looking at WireShark while it was running, and I clearly see a 'CDP' packet which has all the juicy details.
 
In conjunction with some AHK and this - http://www.gossamer-threads.com/lists/cisco/voip/145319#145319 - I'll be able to build my own extension mobility login app.
 
All we really want is an easy way for users to be able to use the PC to log themselves in and out of Extension Mobility - especially if we're planning on going to AD, users are not going to be happy about putting their entire AD username using the TUI.  Thanks!
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