Callmanager DHCP

[ToddGivens]

I am setting up a cisco callmanger network and need some help. When plugged into the switch, the 7960g phone pulls the DHCP address from Callmanger just fine. When I plug a pc into the data port on the phone, it also pulls a DHCP address from Callmanager's dhcp server. I need the data port to access the DHCP server from my windows 2003 machine.

Switch type - 2950
Router type - 1750

It is definetely a issue within the router or switch. Can someone help?

 

[computerhighguy]

The best way to do this is to create a seperate VLAN for
your voice network. This should work on your 2950.

I have configured a voice vlan of 50 and my production vlan of 100. When a phone plugs into the port (in this case a power port), the phone sets up the trunk to use vlan 50 for the phone and use the native vlan for any data on the built in switch. However, if you plug in a regular computer, I belive the port's default configuration is to auto negotiate between trunk and access mode. If not, you can always add the line switchport mode dynamic auto (or desirable). Here is a sample of how my ports are setup.

interface FastEthernet0/1
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport mode trunk
switchport voice vlan 50
spanning-tree portfast

By using seperate VLANS, you seperate the traffic and help to ensure QOS without actually setting it up (although there is no excuse for not setting it up). It also limits the exposure your voice network has to hackers, virus' and broadcast traffic that can effect your voice system.

 

[computerhighguy]

Another option is to just use one DHCP server. If you want to use the Windows 2003 DHCP server, just add the option 150 IP address of your CCM tftp server. This isn't really recommended unless you are running a very small site with just a few phones, but will work.

 

[ToddGivens]

Thanks for your response. What vlan is the port a member of, 50, 100 or neither?

My router has one ethernet interface. I created subinterfaces for each subnet. How does the switch notify the router?

As you can tell, I am not an expert. I am just trying to get by. Any help or suggestions are greatly appreciated.

Todd

 

[ToddGivens]

Whenever I "show interface f0/23", the port I am testing, it says:
Voice Vlan: dot1p (Inactive)

My 7960 is stuck on "configuring ip". Any suggestions?

 

[computerhighguy]

I would suggest getting the docuementation out an reading it. Depending on how many switches you have, you will have to setup a "master" vlan switch witch holds the vlan database. You would then set all the other switches to "slave" so they would receive a copy of the vlan information from the master switch (my terminology is probably wrong, but you get the point). You would set up your router as a dot1q trunk so that it could see all the vlans. Each switch would need to be connected to each other with a dot1q trunk also. Trunks carry all the vlan data that is flowing on the network. Vlans logically seperate your networks so that the dhcp request on vlan 1 is not seen on vlan 2. It is the equivalent of using seperate hubs/switches for each subnet. Only a router cna route packets between different vlans and you can typically setupa switch to do this. Your router may be a better pick depending on what kind of equipment you have. I am going to assume you are running the latest version of IOS on your 2950 and that you only have one (read the documentation if you have more than 1 switch).

Here is how to configure a vlan.

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat2950/12119ea1/2950scg/swvlan.htm

Here is the section onconfiguring a voice vlan.

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat2950/12119ea1/2950scg/swvoip.htm

Youcan also find the documentation for the other version here.

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat2950/

 

[bburton48us]

Hi Todd,

First, DHCP and Call Manager do not mis, I have had call completion problems with as few as 10 phones.

Another solution is to use DHCP services on the router to hand out IP addresses. I have included sample configurations for a router and a switch that do exactly what you are looking for.

Hope this helps you out.

Bill
--------------------------

Router Configuration

ip dhcp excluded-address 172.16.10.1 172.16.10.19
ip dhcp excluded-address 172.16.10.240 172.16.10.254
ip dhcp excluded-address 10.0.110.250
!
ip dhcp pool DATA10
network 172.16.10.0 255.255.255.0
option 150 ip 172.16.10.1
default-router 172.16.10.250
!
ip dhcp pool VOICE110
network 10.0.110.0 255.255.255.0
option 150 ip 172.16.10.1
default-router 10.0.110.250
!
interface FastEthernet0/0
no ip address
duplex auto
speed auto
!
interface FastEthernet0/0.1
encapsulation dot1Q 1 native
ip address 172.16.1.250 255.255.255.0
!
interface FastEthernet0/0.10
encapsulation dot1Q 10
ip address 172.16.10.250 255.255.255.0
ip helper-address 172.16.99.99 (2003 Server for PC DHCP)
ip pim sparse-mode
!
interface FastEthernet0/0.110
encapsulation dot1Q 110
ip address 10.0.110.250 255.255.255.0
ip helper-address 172.16.10.1 (Call Manager for phones)


Switch Configuration

interface FastEthernet0/4
description - Router Trunk Port
switchport trunk encapsulation dot1q
switchport mode trunk
spanning-tree portfast
!
interface FastEthernet0/5
description - IP Phoneport with PC attached
switchport trunk encapsulation dot1q
switchport trunk native vlan 10
switchport mode trunk
switchport voice vlan 110
spanning-tree portfast
!
interface FastEthernet0/6
description - IP Phoneport with PC attached
switchport trunk encapsulation dot1q
switchport trunk native vlan 10
switchport mode trunk
switchport voice vlan 110
spanning-tree portfast
!

 

[Conleyjo]

On our network, we have one DHCP server with a large number of scopes, and use helper addresses for getting all our remote sites to hit the DHCP server over the wan. We use seperate Vlans for the Phones and the data port, but they still use the same DHCP server with the option 150 setting.

What issues are you running into that you cant use the same DHCP server?

 

[ToddGivens]

This post helped a ton. I finally got my vlans configured and working. Thank you tek-tips!!
Todd

 

[NPuser]

I have 2950 as well - when i enter "switchport trunk encapsulation dot1q", i get "invalid input detected at marker - encapsulation". I was supprise to hear that above config worked for you - i was under the impression that 2950 does not support QOS.

sa

 

[bburton48us]

I am using a 2912 with IOS load:

flash:c2900XL-c3h2s-mz-120.5.2-XU.bin


This is an Entertprise version which may support dot1q trunking rather than just ISL.

Hope this helps,

Bill B.