Bug #2768

OsmoBSC doesn't perform MGCP DLCX in all cases of channel release

Added by laforge 3 months ago. Updated 5 days ago.

A interface
Target version:
Start date:
Due date:
% Done:


Spec Reference:


Whenever we performed CRCX on one or multiple MGCP connections on osmo-mgw, we must also call DLCX to clean up.

There are situations like at least the one seen in the attached PCAP file in which CRCX+MDCX are called, but the media gateway never sees a DLCX.

I've seen this cause follow-on problems if more connections are allocated on the same endpoint, at which the mgw will refues as only two connections are permitted by endpoint.

We should have a state machine that ensures whever the SCCP connection is closed, and that SCCP connection had MGCP connections, that those MGCP connections are deleted.

crcx-mdcx-ciph_mod_rej-no_dlcx.pcapng (5.19 KB) laforge, 12/17/2017 08:06 PM


#1 Updated by laforge 3 months ago

  • Assignee changed from sysmocom to dexter

#2 Updated by laforge about 2 months ago

  • Priority changed from High to Urgent

#3 Updated by dexter about 2 months ago

The revised implementation that uses the GSCON FSM (see also should fix this problem. When the GSCON FSM terminates it must make sure that the connection is deleted.

#4 Updated by dexter about 1 month ago

Note: This problem should be fixed with the GSCON FSM.

#5 Updated by dexter about 1 month ago

(see also #2823)

#6 Updated by dexter 5 days ago

  • Status changed from New to Resolved
  • % Done changed from 0 to 100

This is Fixed by GSCON (

Also available in: Atom PDF