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New Member

VoIP + VLAN's

Hi there, this might sound like a stupid question, but I have a small

problem with my VoIP. I had it working until I tried to split the call manager, my gateways and my IP phones into different VLANs.

From my Call manager I can Ping all the elements in my network via there IP numbers, so there is no routing problem

I have my Cisco call manager in VLAN 6, and I have my IP phones in

VLAN 7, each with different Subnet Masks. My phones I configured with Static IP addresses, and I also configured the TFTP server.

All my elements in my network has static IP addresses, I am running

callmanager 3.2. When I add/configer a phone on the Call manager, I have to put in the MAC address of the phone, so what happends ? Why can I not put in the IP number of the phone?? Does the call manager ARP for the phones IP ?? cause if it does, how do I make it to arp outside its logical network, if I can do that.

Thanks for you help

Michael Jeffries

1 ACCEPTED SOLUTION

Accepted Solutions
New Member

Re: VoIP + VLAN's

The phones do not need to be on the same subnet as the CCM's. A good network design would actually dictate putting them on seperate vlans.

When the phones are using DHCP or have their IP Address manually configured, the phones do not initially know where the CCM's are. The phones are given the TFTP Server address either from DHCP or manually and the phone looks to the TFTP server for a list of CCM's.

Here's a link on troubleshooting the IP Phones connection to Call Manager:

http://www.cisco.com/en/US/partner/products/hw/phones/ps379/products_administration_guide_chapter09186a0080080689.html

Once the phones have the correct Call Managers listed, it will attempt to connect to the first CCM in the list, if it cannot create a connection to the Primary CCM then it will go through the listed CCM's.

If the phone successfully connects to a CCM, it will then attempt to register with the CCM, if registration is not successful, then you'll see a "Registration Rejected" message on the phone screen and the phone will just keep retrying to register with the CCM (creating quite a few entries in the event viewer).

The registration rejected message means that the phone is either not configured in CCMAdmin, or there is a problem with how it is configured in CCMAdmin.

tm

Tim Medley, CCNP+Voice, CCDP, CWNA

Sr. Network Architect

VoIP Group

iReadyWorld

5 REPLIES
New Member

Re: VoIP + VLAN's

What about the default gateway (router)on the phones is that set anf tftp server set correctly on phones-->cm pub, check your settings you have layer 3 connectivity so thats good.Are any other phones working.

Check the services in CM are running.

The different vlans wont matter if your configs are correct i.e sub interfaces (router) trunk port switch 802.1q etc.

Have a look at this URL for the rgistration process.

http://www.cisco.com/en/US/products/hw/phones/ps269/products_tech_note09186a008009485a.shtml#rp

New Member

Re: VoIP + VLAN's

Are you saying that when you go into CCMAdmin and add a new phone, you are trying to put the IP Address of the phone in the "MAC Address" field in the Phone Configuration/Device Information screen?

This won't work. The "MAC Address" field is looking for the MAC Address of a device, this is what gets written into SQL and the TFTP config file for the phone. The idea is that the MAC Address never changes, the IP Address could change.

tm

Tim Medley, CCNP+Voice, CCDP, CWNA

Sr. Network Architect

VoIP Group

iReadyWorld

New Member

Re: VoIP + VLAN's

Well what I am saying is that I tried to put the IP address in there. I know that it supposed to be the MAC address, I have changed it again.

What I am asking is why do they have to be on the same VLAN ? Why are the phones trying to broadcast? when I entered the IP number of the TFTP server on the phone? I mean they are supposed to broadcast only if they DHCPing?? Am I not correct by saying that the phones knows who its call manager is and therefore should send a RRQ dirrect to that call manager ?

Why will the phones not register? I heard that I have to use ip address-helper to allow these phones to broadcast via the routing device, but it opens the network up more.

New Member

Re: VoIP + VLAN's

They do not have to be in the same VLAN

It sounds like you have a misconfiguration error.

Plug a sniffer to the back of a phone and filter what the phone -->CM (ip addresses)are recieving sending.

when a phone boots it eventually looks for CiscoCM1.your.domain try using the ip host command CiscoCM1 XXX.XXX XXX see what happens.

New Member

Re: VoIP + VLAN's

The phones do not need to be on the same subnet as the CCM's. A good network design would actually dictate putting them on seperate vlans.

When the phones are using DHCP or have their IP Address manually configured, the phones do not initially know where the CCM's are. The phones are given the TFTP Server address either from DHCP or manually and the phone looks to the TFTP server for a list of CCM's.

Here's a link on troubleshooting the IP Phones connection to Call Manager:

http://www.cisco.com/en/US/partner/products/hw/phones/ps379/products_administration_guide_chapter09186a0080080689.html

Once the phones have the correct Call Managers listed, it will attempt to connect to the first CCM in the list, if it cannot create a connection to the Primary CCM then it will go through the listed CCM's.

If the phone successfully connects to a CCM, it will then attempt to register with the CCM, if registration is not successful, then you'll see a "Registration Rejected" message on the phone screen and the phone will just keep retrying to register with the CCM (creating quite a few entries in the event viewer).

The registration rejected message means that the phone is either not configured in CCMAdmin, or there is a problem with how it is configured in CCMAdmin.

tm

Tim Medley, CCNP+Voice, CCDP, CWNA

Sr. Network Architect

VoIP Group

iReadyWorld

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