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  • 156 information not getting to phone

    Hello all. I'm a new Shoretel admin. Currently we have two VLAN's setup in a mixed Adtran/Cisco environment. Currently the phones on the Adtran switches are working, but anything plugged into the Cisco switches aren't receiving their 156 information and ultimately aren't getting a voice IP address. The data vlan is fine and the pc plugged into the phone is working. Spanning tree is setup. Are there any known issues with Cisco blocking this information? The two switches in particular are 3750G-PoE and 3650G-PoE.

    Also, should the 156 option be in both DHCP scopes, or just the voice scope?

    TIA.
    Last edited by jfrost; 11-30-2009, 02:54 PM.

  • #2
    Turn off spanning tree.

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    • #3
      Originally posted by 400degreez View Post
      Turn off spanning tree.
      Already turned off. We've been using Wireshark today for monitoring. We're seeing DHCP information being passed to the phone (including the 156 option) but the phone is getting 2 NAK's before giving up.

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      • #4
        Originally posted by jfrost View Post
        the phone is getting 2 NAK's before giving up.
        What vlans are assigned to the switch port connected to the DHCP server?

        Data untagged only should work fine.
        Data untagged and voice tagged will give you problems.

        Option 156 needs to be in both scopes. On the data scope you need only specify
        layer2tagging=1, vlanid=*
        which is enough for the phone to notice it is supposed to be on another vlan.

        Additionally Microsoft DHCP using Superscopes have been problematic. If the voice scope is within a superscope we have seen the wireshark trace showing that Microsoft DHCP server gives out an IP on the data vlan, the phone reboots onto the voice vlan and MS DHCP tries to issue the same IP address again from the data scope again.
        Last edited by ShoreTel_Dave; 12-01-2009, 01:18 PM.

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        • #5
          Originally posted by ShoreTel_Dave View Post
          What vlans are assigned to the switch port connected to the DHCP server?

          Data untagged only should work fine.
          Data untagged and voice tagged will give you problems.

          Option 156 needs to be in both scopes. On the data scope you need only specify
          layer2tagging=1, vlanid=*
          which is enough for the phone to notice it is supposed to be on another vlan.

          Additionally Microsoft DHCP using Superscopes have been problematic. If the voice scope is within a superscope we have seen the wireshark trace showing that Microsoft DHCP server gives out an IP on the data vlan, the phone reboots onto the voice vlan and MS DHCP tries to issue the same IP address again from the data scope again.
          Didn't know that about the 156 entries. Didn't work with the change though. VLAN1 is for data and VLAN20 is for voice. No superscopes are in use and LLDP is turned off as well.

          What we see in the Wireshark capture is that the phone originally requests an IP from VLAN1 and accepts it. The phone reboots and makes a request for an IP from VLAN20. The DHCP server makes two offers for an IP address, but the phone never accepts the offer.

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          • #6
            Can you ping anything in the voice vlan with a static address such as the default gateway of the voice vlan or a shoregear switch from the DHCP server?

            The offers from dhcp need to be routed back to the voice vlan so the ability to ping something in voice vlan will confirm this is working.

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            • #7
              No dhcp with cisco

              Hi, I am having a similar problem but only at 2 of our sites.
              According to our network manager the 2 sites with the issue are cisco switches are running a specific IOS version:
              C1841-SPSERVICESK9-M-12.4(24)T1

              I don't handle the network, just the complaints as a result. The only workaround I have found is to static assign the phones.

              Chris

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