VOIP Packet DSCP marking at ALGs

VoIP DSCP marking at Application Layer Gateways (ALGs) enables you to enforce class-of-service distinctions on voice traffic traversing your network. You can use this feature to improve VoIP quality in congested networks by ensuring RTP packets receive higher routing priority and faster forwarding. The feature works by reading a configured 6-bit DSCP value at the ALG level and applying it to the CoS field of outgoing RTP packets?beginning with the first packet and continuing for all subsequent packets in that session. You can configure DSCP marking independently for SIP, H.323, MGCP, and SCCP protocols. The goal is to guarantee that all RTP packets encountering the ALG are assigned the appropriate DSCP value, preventing VoIP quality degradation caused by network congestion.