M200 DHCP issue with Cisco VoIP phones

edited November 2021 in Technical Discussion

We have Cisco 7841 and 8851 phones and they are losing connection randomly and will either come back up if I reboot the firewall itself or if left alone long enough they will just start working again. They are getting the correct dhcp address from the firewalls voice vlan network. traffic is tagged. When the phones go down I start seeing denies on the firewall and when they come back up these denies disappear. I don't have much experience so I am not sure what the firewall is trying to tell me. Has anyone experienced this?
image attached to see the denies.

example = 54031/udp 50-VOIP_IP firebox denied 316 64 (unhandled internal packet-00)




  • Options

    The destination packets are broadcast packets, and will always be denied at the firewall interface - so they are not an issue here.

    Consider opening a support incident to get help from a WG rep in understanding this, and hopefully fixing it.

  • Options

    Hi Bruce, thanks for the quick response. Any reason I would only see these broadcast packets when the phones went offline and once they are back up they disappear. I just find that part odd.
    Also I can see dhcprequests for the phones and there is a dhcpack but its just continues like this for quite sometime almost the the response isn't getting back to the phones.

  • Options

    As I am not a Cisco phone expert - no idea.
    Consider asking your Cisco phone provider

Sign In to comment.