I meet an issue that some endpoints (SX20、SX80) drop the call from MCU. and the log is H.245 network connection error.
now the condition is all endpoints and MCU register in VCSC. all call by H.323
MCU version 4515.
can someone help me？
and an amazing thing that an endpoint and MCU are in the same VLAN. the endpoint is SX 20. it also drops from MCU (H.245 network connection error)
Everything you have is SIP capable and you can register both the endpoints and MCU with both protocols so it won't screw up your phonebooks, etc. You are past end of support on that MCU by the way.
I know you stated that everything is on the same VLAN, are you sure about that? If you have H.245 signalling failing generally that's due to it being blocked somewhere - router access list, firewall, etc. Are you 100% positive there is nothing between your endpoints and the MCU?
Since the MCU is old, another simple question - obviously this used to work, what changed between when it did and when this problem started occurring? Something changed, I doubt this is a hardware problem. Was there router changes, firewall changes, etc? If so that's where you should start looking - there is generally no such thing as coincidence when it comes to network problems.
In addition to what @PJMack wrote above (which is all good information), you could try running a "ping -t" to the endpoint and MCU while the call is progressing and that way you may be able to see one or the other dropping out and that may help possibly point you to where any network issue is occurring, whether in the spot where the MCU is, or where the endpoint is. But from reading all your posts above, it appears that the issue is only happening when you are in a call with the MCU - which points more to that part of the network, or the MCU itself, having some kind of failure.