have two devices that communicate over Ethernet/IP - cannot get them conncted so found a Hub and connected them and my PC running Wireshark - what I see is the Client (192.168.144.11) device making a connection to the Server device (192.168.144.130) but then the Client goes to following: 239.192.17.32 IGMP V2 Membership Report Join group 239.192.17.32 when it should simply continue talking to the Server device - consequently the connection between my devices' fails Can anyone help me understand where this could come from asked 17 Mar '11, 18:12  tonyh110 retagged 18 Mar '11, 09:52  packethunter |
One Answer:
Bill, thanks for your reply - yes its industrial CAN bus over TCP/IP - once the Client device makes a connection then a CIP CM transaction opens - because the Client starts this IGMP request the Server device stops responding at the CIP level I have the Client device vendor working on the problem - but your answer helps me understand this much better - thing is Industrial Networks are deterministic and wont suffer timeouts (which begs why do they put such critical stuff through a non-deterministic transport layer) answered 18 Mar '11, 07:43 tonyh110 |
I'm not familiar with Ethernet/IP (by which I'm assuming you mean Industrial Protocol) so I'll just note the following:
IGMP is a protocol in it's own right completely separate from TCP (which is presumably the protocol being used in "making a connection").
The IGMP message is merely the client requesting to receive multicast messages from group 239.192.17.32 so I suspect "consequently the connection between my devices' fails" is not really correct.
What do you mean by "cannot get them connected" ? Does the TCP 3-way handshake complete ?