B-3
Cisco BTS 10200 Softswitch Troubleshooting Guide, Release 5.0.x
OL-8723-19
Appendix B System Usage of MGW Keepalive Parameters, Release 5.0
Keepalive for Release 5.0 Prior to Maintenance Release 1.1
Definitions and Additional Parameters
This section defines some of the terms used to describe the KA process.
•
KA procedure—A series of transmissions and retransmissions of AUEP messages used to determine
the MGCP connectivity status between the BTS 10200 and the MGW. If there is a loss of
connectivity, the BTS 10200 retries the series of AUEP transmissions up to a specified number of
retries (defined by
mgcp-keepalive-retries
) before declaring the MGW to be in
down status
.
•
KA attempt—The transmission of an AUEP message, with a defined number of retransmissions of
the same AUEP message, until an ACK message is received or the defined number of
retransmissions has been reached. This can include retransmissions to additional IP addresses if
provisioned to do so. A KA attempt is defined as successful if an ACK is received from the MGW,
and failed if no ACK is received after the defined number of AUEP retransmissions. A KA attempt
is also called an AUEP transaction.
•
KA retries—Subsequent KA attempts, sent only if the initial KA attempt fails.
•
MGW in
working status
—A KA attempt to this MGW is successful (an ACK is received).
•
MGW in
down status
—After a defined number of KA retry failures, the BTS 10200 declares this
MGW to be in
down status
, and continues to perform the KA procedure.
Note
To learn more about the MGW operational states reported by the BTS 10200, see the MGW table in the
Cisco BTS 10200 Softswitch CLI Database
The system uses the parameters
mgcp-max1-retries
and
mgcp-max2-retries
to limit the number of
retransmissions of the same AUEP. You can adjust the parameters
mgcp-max1-retries
and
mgcp-max2-retries
, if necessary, to improve response if there are network bandwidth or reliability
issues, or if a MGW is slow in responding to commands from the Call Agent. These parameters are based
on the description in RFC 3435, Section 4.3, and are defined as follows:
•
mgcp-max1-retries
= Number of AUEP retransmissions sent to a single IP address before selecting
the next IP address for this MGW listed in the DNS server (default = 2).
•
mgcp-max2-retries
= Number of AUEP retransmissions sent to the last IP address for this MGW
listed in the DNS server (default = 3).
The following parameters are also related to MGW connection status, but are not discussed in detail in
this appendix. For additional details, see the
BTS 10200 Command Line Reference Guide
.
•
Long transaction (applicable to NCS endpoints)—The
mgcp-t-longtran
field in the
mgw-profile
table specifies the initial MGCP transaction timeout (in seconds) after receiving a provisional
response (return code 100) from the MGW. The range is 1–10 (default = 5).
•
Return code action—The endpoint action (
ep-action
) field in the Media Gateway Control Protocol
Return Code Action (
mgcp-retcode-action
) table specifies what action to take when an MGCP
message is received from an MGW.
