IPT, catalyst 4500 + Nortel phones

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Mar 26th, 2007
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Hi all


As you will probably be able to tell i'm very new to VOIP !!!.


We are implementing a nortel IPT solution on a Cisco switching infrastructure. The user PCwill be connected to the Nortel phone which is then connected to the 4500. I have a couple of questions:


1) The following is taken from the config guide on the 4500 to configure a voice port on the 4500.


=========================================

conf t

interface gi0/1

switchport voice vlan 2


So vlan 1 carries data traffic and vlan 2 carries voice.


=========================================


I don't want the data to be carried on vlan 1 so how do i configure a data vlan ? ie if i wanted vlan 10 for data is it just


conf t

interface gi0/1

switchport voice vlan 2

switchport access vlan 10


So vlan 2 is for voice and vlan 10 is for data ?


2) The Nortel phones don't use CDP obviously, however they are capable according to their docs of supporting full DHCP configuration. The description given of how this works is


When the phone boots up it broadcasts out for a DHCP address. This is done on the default vlan ?? ie the one configured with the "switchport access vlan xxx" command. (which is part of the reason for question 1). Assuming this is the data vlan when it gets the offer back within the DHCP packet is the vlan ID of the voice vlan. The phone then rejects the DHCP offer and sends a new DHCP request on the voice vlan.


Does this sound right ?. Does anyone have experience of using this and does it work as suggested.


Any help much appreciated


Jon



Correct Answer by Rob Huffman about 10 years 4 months ago

Hi Jon,


Here is some more info (If you can't get to the 3rd link let me know as you need a Nortel Login);


Nortel


Like Avaya, Nortel phones do not use the Cisco Discovery Protocol to determine the voice VLAN, but instead relies on configuration information supplied by the DHCP server. When the Nortel phone boots, it displays a test pattern and the speakerphone and message waiting lamps light. The phone requests an IP address (on the native VLAN) from the DHCP server. The server responds with an IP address and a VLAN ID. The phone reboots and requests a new IP address on the voice VLAN by tagging all Ethernet frames with the VLAN ID.


The DHCP server responds with a new IP address and a list of call server (IP PBX) addresses. The phone displays "Locating Server?", connects to the call server, optionally downloads updated firmware and attempts to register. If successful, you will either see a normal phone display or the prompt "Node: xx?" Either one indicates that the phone can communicate with the call server. From a networking perspective, everything is working properly.


From this doc;


http://enterprisenetworksandservers.com/monthly/art.php?1158


Check out this testing;


http://www.netmasterclass.net/site/articles/Voice%20VLAN,%20dot1q%20and%20dot1p%20encapsulations.pdf


Have a look at Appendix B;


https://app49.nortelnetworks.com/cgi-bin/HelmExpress/pdfcgi2/helmsman/helmdata/docubase/IP2002/pdf/553-3001-368_22.00_Config.pdf


Hope this helps!

Rob

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Rob Huffman Mon, 03/26/2007 - 09:27
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Hi Jon,


I have not done this setup but I thought this info might help you out;


http://forum.cisco.com/eforum/servlet/NetProf?page=netprof&forum=Unified%20Communications%20and%20Video&topic=IP%20Telephony&CommCmd=MB%3Fcmd%3Dpass_through%26location%3Doutline%40%5E1%40%40.1ddce86f/0#selected_message


http://forum.cisco.com/eforum/servlet/NetProf?page=netprof&forum=Security&topic=AAA&CommCmd=MB%3Fcmd%3Dpass_through%26location%3Doutline%40%5E1%40%40.1ddc6ad5/6#selected_message


http://forum.cisco.com/eforum/servlet/NetProf?page=netprof&forum=Unified%20Communications%20and%20Video&topic=Video%20over%20IP&CommCmd=MB%3Fcmd%3Dpass_through%26location%3Doutline%40%5E1%40%40.1dda2c72/0#selected_message


Network Policy Discovery


This capability is one of the most important because it provides a mechanism for a switch to notify a phone the VLAN number that it should use. The phone can plug into any switch, obtain its VLAN number, and then start communications with the call control.

Network policy discovery solves the major problem today with third-party phones working with Cisco switches as well as Cisco phones working with third-party switches. For both of these cases, an inter-working problem makes deployment problematic.


Third-Party Phones with Cisco Switches


Some third-party phones receive their VLAN information through Dynamic Host Configuration Protocol (DHCP), meaning that these phones must first boot up, get an IP address on the native VLAN, get voice VLAN information from the DHCP server, and then boot up again using the voice VLAN. In other cases the phones must be individually configured to assign their VLAN address.


http://www.cisco.com/en/US/tech/tk652/tk701/technologies_white_paper0900aecd804cd46d.shtml


Hope this helps!

Rob

Jon Marshall Mon, 03/26/2007 - 12:28
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Hi Rob


Many thanks for your help. I did read those NetPro links before i posted and i think this is where my confusion comes from. I appreciate you haven't done a Nortel implementation but just in case you can shed some light on this.


One of the links suggests that you configure the connection between the phone and the switch as a trunk link. This corresponds to what Nortel told us. When i asked them how the phone configures itself they said that the phone DHCP's out on the default vlan, gets an IP address with some additional options, one of which is the voice vlan ID. It then rejects that IP address and DHCP's out on the voice vlan.


But to my understanding a trunk does not have a default vlan. It has a native vlan but for security reasons this is a non-routable vlan in our company. Nortel were at a loss to explain how their phone would fully configure itself from DHCP.


I have now been told that the phone will use the vlan that has been configured as


"switchport access vlan "vlan number"


which to my understanding would be the data vlan.

Once again it woud DHCP out on that vlan, get IP address back with voice vlan ID etc....


This is where my confusion is. If i configure the link as a trunk then i can't see how the Nortel phone will work, unless i partially configure the phone with vlan information.


So maybe i should configure the phone with


switchport access vlan "data vlan"

switchport voice vlan "voice vlan"


Any ideas.


Jon




Correct Answer
Rob Huffman Tue, 03/27/2007 - 06:13
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Hi Jon,


Here is some more info (If you can't get to the 3rd link let me know as you need a Nortel Login);


Nortel


Like Avaya, Nortel phones do not use the Cisco Discovery Protocol to determine the voice VLAN, but instead relies on configuration information supplied by the DHCP server. When the Nortel phone boots, it displays a test pattern and the speakerphone and message waiting lamps light. The phone requests an IP address (on the native VLAN) from the DHCP server. The server responds with an IP address and a VLAN ID. The phone reboots and requests a new IP address on the voice VLAN by tagging all Ethernet frames with the VLAN ID.


The DHCP server responds with a new IP address and a list of call server (IP PBX) addresses. The phone displays "Locating Server?", connects to the call server, optionally downloads updated firmware and attempts to register. If successful, you will either see a normal phone display or the prompt "Node: xx?" Either one indicates that the phone can communicate with the call server. From a networking perspective, everything is working properly.


From this doc;


http://enterprisenetworksandservers.com/monthly/art.php?1158


Check out this testing;


http://www.netmasterclass.net/site/articles/Voice%20VLAN,%20dot1q%20and%20dot1p%20encapsulations.pdf


Have a look at Appendix B;


https://app49.nortelnetworks.com/cgi-bin/HelmExpress/pdfcgi2/helmsman/helmdata/docubase/IP2002/pdf/553-3001-368_22.00_Config.pdf


Hope this helps!

Rob

Jon Marshall Tue, 03/27/2007 - 06:48
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Rob


Thanks very much for this, much appreciated.


I guess from reading what you have put that i can just configure the port as a trunk and make sure that native vlan is actually a routable vlan in our environment.


Only issue i can see is that my data vlan will need twice as many addresses as my voice vlan because if the phone temporarily borrows an IP address from the data vlan this scope might run out of IP addresses for the PC's.


Once again many thanks and i might be back with some more questions later on :-)


Jon

Darren Ramsey Fri, 03/30/2007 - 20:45
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It works just fine. Basically the phone boots up and gets a temporary DHCP address from the data Vlan. Set up a Vendor class string for "Nortel-i2004-A" and send options 128 and 191 with the proper parameters. The phone changes itself from what I'd call access mode to trunk mode and does a DHCP discover on the voice Vlan that is sent in Option 191. The only issue I saw was the phone did not release the temporary DHCP address in the data Vlan.


Configure your switch with voice and data Vlans, and then follow the attached guide. Hopefully in the future both Cisco and Nortel will support LLDP and all this DHCP stuff will be irrelevant. The only part I'm not sure about is to trust COS or DSCP.


Let me know if you have any other questions.



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