Troubleshooting guide

4-5
Cisco Broadband Local Integrated Services Solution Troubleshooting Guide
OL-5169-01
Chapter 4 Troubleshooting with Call Flows
Understanding MGCP
Connection Mode (M)
Each connection is qualified by a connection mode parameter, which can be set to send, receive,
send/receive, inactive, loopback, or continuity test.
The handling of the audio signals received on these connections is determined by the parameters:
• Audio signals incoming from connections in receive or send/receive mode are mixed and sent to
the endpoint.
• Audio signals originating from the endpoint are transmitted over all connections whose mode is
send or send/receive.
• If the mode is set to loopback, the gateway is expected to return the incoming signal from the
endpoint back to that same endpoint.
• If the mode is set to continuity test, the gateway is informed that the other end of the circuit has
initiated a continuity test procedure. It is expected to follow the procedure specified for that
endpoint, which may require either that the circuit be placed in loopback mode, or to wait for a
specific tone and return an appropriate signal.
Note There are two types of continuity tests: loopback and two-tone. It is important that the gateway be
configured to reply correctly with the requested test signal; otherwise the test fails, the time slot being
tested is taken out of service, and the test is repeated on the next available channel, which again fails,
and is taken out of service, and so on until the testing threshold is reached. By that time, several time
slots are temporarily not available, which can affect service.
Table 4-3 lists possible Connection Mode values
.
Requested Events (R)
The requested events parameter is a list of events that the gateway is requested to detect and report. Each
event is identified by a code, as shown in Table 4-4.
These ASCII encodings are not case-sensitive. Values such as “hu”, “Hu”, “HU”, or “hU” are considered
equivalent.
Table 4-3 Connection Modes
Connection Mode Meaning
M: sendonly The gateway should only send packets.
M: recvonly The gateway should only receive packets.
M: sendrecv The gateway should only send and receive packets.
M: inactive The gateway should neither send nor receive packets.
M: loopback The gateway should place the circuit in loopback mode.
M: contest The gateway should place the circuit in test mode.
Table 4-4 Requested Events
Event Code
Fax tones ft
Modem tones mt