Quality of Service

QoS is set on all audio packages (UDP port 61000:61150) using Diffserv bit class EF (http://en.wikipedia.org/wiki/DiffServ#Expedited_Forwarding_.28EF.29_PHB)

The TOS byte in the IP header is set to DSCP (Diffserv) (http://en.wikipedia.org/wiki/Type_of_Service)

The Linux console must be used to check if QoS is active:

# iptables –t mangle –L –v

To change QoS settings:

# nano /opt/amc/scripts/networking

The following lines configures QoS:

# set DSCP class EF on all outgoing VoIP packages  iptables -t mangle -A OUTPUT --protocol udp --destination-port 61000:61150 -j DSCP --set-dscp-class EF

The rule: ”udp dpts:61000:61150 DSCP set 0x2e” on the chain “OUTPUT” tells the linux kernel to set the DSCP field in the IP-header to hex 0x2e for all outgoing UDP packets within the port range 61000:61150. You can from the iptables command read out the number of packages and bytes this rule has been applied to.

The DSCP value 0x2e is also called Expedited Forwarding (EF). For details on the bits of the DSCP field in the IP header see: http://www.cisco.com/warp/public/105/dscpvalues.html