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Configuring DHCP on a layer 3 Switch for an Ip phone

Im having issues giving this IP Phone an IP via DHCP on a layer 3 switch connected to a router that has a telephony service setup. The phone should be on VLAN 20.

7 Replies 7

Hi

 After some work here, I got this log:

"%IPPHONE-6-REGISTER: ephone-1 IP:20.10.10.11 Socket:2 DeviceType:Phone has registered."

Sounds good right. The phone finally registered to the Router.

You can see the file I attached and let me explain what did I see wrong on your project.

On the Router, you did not need two interfaces. As long as you connected the L3 switch on the interface

FastEthernet0/1, you had to create the subinterface FastEthernet0/1.20, config the encapsulation dot1q on it and put the IP address 20.10.10.1 255.255.255.0.

 

Then, you Telephone config should looks like thiss:

 

telephony-service

max-ephones 4

max-dn 4

ip source-address 20.10.10.1 port 2000

auto assign 4 to 6

auto assign 1 to 5

 

This is it for the Router.  For the L3 switch, you should put the interface with the Router in trunk mode. No need to L3 interface.

You also missed this line: "ip dhcp excluded-address 20.10.10.1 20.10.10.10".  This line is important because it prevents the DHCP service to assign the IP address 20.10.10.1 or 20.10.10.2 to the Phone. This two IP address is already taken and should not be assigned to any other device.

 

Well, I think this is it.

 

 

For this particular instance I need the L3 interface on the multilayer switch and that's what I'm confused about.

Right, no problem. It is also possible. See the file attached.

 But now, you need to do some changes on the devices. You need to enable IP routing on the L3 switch, keep the interface between Router and L3 switch with Ip address and do soma changes on the DHCP pool and on the Phone service.

Walk through the file I attached which is working and take  a look

 

I'm having an issue getting the IP Phone registered to the router when phone is directly connected to the L3 Switch with switchport access/voice VLAN configured on the interface. IP routing and DHCP is enabled on the core SW and its directly connected to the router with IP. static route to vlan20 network is also configured. 

The IP phone was only registered successfully on the layer 2 switch with switchport access/ voice vlan. This only happen when Layer 3 switch has inter-Vlan configured. It works on trunk mode with voice VLAN on the port. What's the difference when interface vlan is configured on the layer 3 switch the normal switch. I have attached the file.

 

Hello @kram0925 

 Please, create a new post and share the link here and I can help you.

Hi can you share all the configs you have done from switch to router? Thanks alot. newbie here

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