Cisco Systems A9014CFD Frame Delay and Frame-Delay Variation, Two-way Delay Measurement, 11-3

Chapter 11 ITU-T Y.1731 Performance Monitoring

Information About ITU-T Y.1731 Performance Monitoring

Figure 11-1 A Point-to-Point Metro Ethernet Deployment with Typical Maintenance Entities and

		Maintenance Points
Subscriber			Service Provider				Subscriber
Equipment		Operator A NEs			Operator B NEs		Equipment
1	2	3	4	5	6	7	8
			Subscriber
			MEG
			Test MEG
			EVC ME
		Operator A			Operator B MEG
UNI MEG			E-NNI ME				UNI ME

281942

MEP (up orientation)

MEP (down orientation)

Logical path of SOAM PDUs

Frame Delay and Frame-Delay Variation

Ethernet frame Delay Measurement (ETH-DM) is used for on-demand Ethernet Operations,

Administration & Maintenance (OAM) to measure frame delay and frame-delay variation.

Ethernet frame delay and frame delay variation are measured by sending periodic frames with ETH-DM information to the peer MEP in the same maintenance entity. Peer MEPs perform frame-delay and frame-delay variation measurements through this periodic exchange during the diagnostic interval.

Ethernet frame delay measurement supports hardware-based timestamping in the ingress direction.

These are the two methods of delay measurement, as defined by the ITU-T Y.1731 standard, One-way ETH-DM (1DM) and Two-way ETH-DM (2DM). However, the Cisco ASR 901 router supports only Two-way ETH-DM.

Two-way Delay Measurement

Two-way frame delay and variation can be measured using DMM and Delay Measurement Reply (DMR) frames.

In two-way delay measurements, the sender MEP transmits a frame containing ETH-DM request information and TxTimeStampf, where TxTimeStampf is the timestamp of the time at which the DMM is sent.

When the receiver MEP receives the frame, it records RxTimeStampf, where RxTimeStampf is the timestamp of the time at which the frame with ETH-DM request information is received.

The receiver MEP responds with a frame containing ETH-DM reply information and TxTimeStampb, where TxTimeStampb is the timestamp of the time at which the frame with ETH-DM reply information is sent.

	Cisco ASR 901 Series Aggregation Services Router Software Configuration Guide
OL-23826-09		11-3