IP Touch 4068 via VPN tunnel PROBLEM

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Hi,
I'm late, I know. But if someone is interested why this setup can't work, here my theory:
CPU has sent out the initial UAUDP packet with vlan tag 2 to establish an IP NOE connection between 7775(oxo) and 5001(phone). This packet gets through the VPN tunnel to the phone as untagged IP packet. The phone answers and in the payload of the UAUDP protocol it tells in which vlan itself is. You can see this in packet no. 48 in the tcpdump trace:

Code: Select all

Universal Alcatel/UDP Encapsulation Protocol, Connect-Message:
Opcode: connect
...
Keepalive: 9
QoS IP TOS: 0
QoS 802.1 VLID: 0
QoS 802.1 PRI: 255

The phone says it is in vlan-id "0". With this information in payload the packet reaches the other side of the VPN tunnel, gets tagged with 802.1 vlan-id=2 and reaches the CPU. The CPU expects VLID=2 instead of VLID=0 and drops this answer from the phone. This game goes on for about 10 seconds until the phone closes its application listening on port 5001 (this is why you see the ICMP messages) and reinitiate the UAUDP connection and starts again with TFTP get to get the BASE-PORT of the CPU (packet no. 178 in the trace remote_ip_touch).

just a theory.