Cisco Systems ASR 1000 manual Dscp Marking and IP Precedence Marking, Dscp Re-Markings

Chapter 5 Quality of Service and Bandwidth Management

DSCP Marking and IP Precedence Marking

Table 5-1		Asymmetric Flow Policing—Independent Behavior of Signaling and Media Flows on Two Sides of a Media
		Gateway
				Access Side (AC)
	tman/pol		Absent	ON	OFF
	Property
		Absent	Signaling: No policing	Signaling: Policing per Tman	Signaling: No policing on AC and
			Media: Policing per SDP	parameters on AC and no policing	BB
				on BB
					Media: No policing on AC and
				Media: Policing per Tman	policing per SDP on BB
Back				parameters on AC and per SDP on
				BB
Bone
Side		ON	Signaling: Policing per Tman	Signaling: Policing per Tman	Signaling: No policing on AC and
(BB)			parameters on BB and no	parameters on AC and on BB	policing per Tman parameters on
			policing on AC	independently	BB
			Media: Policing per Tman	Media: Policing per Tman	Media: No policing on AC and
			parameters on BB and per SDP	parameters on AC and on BB	policing per Tman parameters on
			on AC	independently	BB
		OFF	Signaling: No policing on BB	Signaling: No policing on BB and	Signaling: No policing on BB and
			and AC	policing per Tman parameters on	AC
			Media: No policing on BB and	AC	Media: No policing on BB and AC
			policing per SDP on AC	Media: No policing on BB and
				policing per Tman parameters on
				AC

DSCP Marking and IP Precedence Marking

The DBE supports marking of differentiated services code point (DSCP) bits and IP precedence marking for egress traffic and media relay. Using standard router features, these markings can be used to prioritize packets for faster delivery or for lower risk of drop under congestion.

The DBE supports statistics collection and saves all QoS statistics, including packets transmitted per second and packets dropped for exceeding allocated bandwidth on a per-call or per-interface basis.

DSCP Re-Markings

For every media stream, the DBE receives a DSCP value to use in the Real-time Transport Protocol (RTP) and Real-time Control Protocol (RTCP) packets. The DBE receives these values at the call setup time on a per-flow basis and maintains the values as a part of the connection table entry. The DBE modifies the type of service (TOS) bits in the IP header for every outgoing packet and updates the checksum accordingly.

Cisco IOS XE Integrated Session Border Controller Configuration Guide for the Cisco ASR 1000 Series Aggregation Services Routers

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