IP Phones Fail to Get a IP address


  • I have a site that has 6 vlans.  

    The Default gateway is a 5412ZL Switch.  Routing Enabled. 

    Vlan 2 is client computers Vlan 3 is servers Vlan 4 Is IP phones Vlan 5 Legacy Network  Vlan 8  PCI

    Phones are Shoretel IP230 Phones

    I can take a laptop or desktop and plug it into any of the ports of the switch and it will get an ip for that vlan.  If i take a IP phone and plug it into any of the vlans it fails. 

    All ports are tagged in Vlan4  and untagged in all the rest.  

    Each vlan has a ip helper with the ip of the dns server 

    each vlan has a Default gateway.  

    in the dhcpsrvlog   

    32,12/10/12,13:15:53,DNS Update Successful,,DELL6520.


    the mac address belongs to the IP phone  

    removing the lease and resetting the phone has not resolved the issue.  rebuilding dhcp has not as well. 

    I ran a packet capture and 

    I have 2 attachments from the capture  the DHCP Discover   

    As you can see from the Next packet i had set up  dhcp reservation for the phone in question it appears the dhcp server is doing the correct thing but the phone never gets it 

    Im at a loss at where the issue is.  Hp states the issue is with the DHCP server Shoretel states its a issue with the server as well. 

    I have not rebooted the switch as if that doesn't fix the issue all the ip phones may not come back on line as they are all POE 

    Tuesday, December 11, 2012 8:51 PM


  • Sounds like a DHCP option is missing that the Shortel phones need.

    If the necessary option exists, and it's a server option and not a scope option, your IP helper/relay agent (shown in the capture) should make sure any and all DHCP clients get their respective options. However, if that is not working, I recommend checking the VLAN config to make sure the helper is configured properly.

    Ace Fekay
    MVP, MCT, MCITP/EA, MCTS Windows 2008/R2 & Exchange 2007, Exchange 2010 EA, MCSE & MCSA 2003/2000, MCSA Messaging 2003
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    This post is provided AS-IS with no warranties or guarantees and confers no rights.

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    Friday, December 14, 2012 6:24 AM