ZyXEL Communications MSC1024G Series User Manual page 545

Figure 376 H.248 Media Gateway SC and MC
C
An MC sends line events (like "onhook" and "offhook" to the SC. The SC sends signal events
(like ring, metering pulse, and various tones) to the MCs. To ensure quality of service, you can
use IEEE 802.1p and/or DSCP for the messages the SC sends to the MGC. These are generally
H.248 protocol messages with a higher priority than other regular packets.
An MC packetizes audio signals from the subscriber line into RTP packets. The SC queries the
MGC and tells the MC the destination media gateway for the RTP packets. The MC terminates
RTP packets from other media gateways and converts them into audio signals for the
subscriber line. You can set the IEEE 802.1p and/or DSCP priority for the RTP packets the
MC sends. At the end of each RTP session the MSC sends a statistics report of the RTP stream
to the MGC.
You can use a backup SC card for higher reliability. If the active SC goes down, the standby
SC automatically takes over. Active calls continue, although calls that the active SC was
setting up are discarded and the users must initiate them again.
MSC1000G/1024G/1224G Series User's Guide
MC
ANALOG
H.248 signaling
Line events
Signal events
RTP payload
SC
IP NETWORK
Other MG
ANALOG
Chapter 18 VoIP
MGC 1
MGC 2
545