Hi Everyone
Not sure if its the right forum for this, but I’ve noticed something rather strange with a D40 that I’m attempting to configure over a WAN connection.
We have a fibre link running from our office to a datacenter where the Asterisk 11 installation (latest FreePBX distro) which has the DPMA module installed on it. I’m manually specifying the Digium Config Server option on the phone to point to the IP of the PBX server in the remote subnet.
What I’m observing via port mirroring is that the phone is sending two fragmented UDP packets destined for the PBX. The first packet is 1514 in length (which is the MTU of the switch port for both the phone and router) and the second is 133 bytes. Reassembled they come to 1579 bytes according to Wireshark. It looks like the the phone is sending a rather large certificate, which I presume is part of the authentication process.
TCPDUMP at the datacenter/PBX end only shows a single packet 39 bytes long that appears to be the end of the reassembled payload according to the hex dump. I get to see “END CERTIFICATE----” which is the end of the reassembled packet.
Is this normal behaviour for the phone to send such a large packet and if so, is there any way to manually adjust the MTU?
Thanks,
Dave
[quote=“davefinster”]
Is this normal behaviour for the phone to send such a large packet and if so, is there any way to manually adjust the MTU?
Thanks,
Dave[/quote]
Yes, it’s normal for the phone to send larger packets, and no, there’s no way to manually adjust the MTU.
Alright - any way to have it do its configuration over TCP instead of UDP or perhaps have DPMA generate .xml or .cfg files that can be accessed over HTTP?
Does Switchvox use the same provisioning method/DPMA or does it have something different?
EDIT: I did locate an MTU issue along the path which allows the phone to get to the list of users, however configuration delivery (“Fetching config from proxy…”) results in a packet of 1610 bytes. I’m guessing that DPMA was never designed to work across a WAN environment?
Phones yes, but phones + DPMA no. You can use the phones without any of the fancy DPMA-enabled features and pull xml configuration files over HTTP(s)/FTP(s).
The same method.
[quote]
EDIT: I did locate an MTU issue along the path which allows the phone to get to the list of users, however configuration delivery (“Fetching config from proxy…”) results in a packet of 1610 bytes. I’m guessing that DPMA was never designed to work across a WAN environment?[/quote]
Is packet re-assembly not happening for you?