Brocade 6910 Ethernet Access Switch Configuration Guide (Supporting R2.2.0.0) - Manual (Page 1077)

Brocade 6910 Ethernet Access Switch Configuration Guide 1021
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Connectivity Fault Management
FIGURE 313 Transmitting Loopback Messages
Transmitting On-Demand Delay-Measure Requests
Use the Administration > CFM (Transmit Delay Measure) pages to send on-demand delay-measure
requests to a specified MEP within a maintenance association. Delay measurement can be used to
measure frame delay and frame delay variation between MEPs.
CLI References
• “ethernet cfm delay-measure two-way” on page 560
• “ethernet cfm delay-measure one-way” on page 559
Command Usage
• Both the source and destination MEP must be configured for the same MA before transmitting
delay-measure messages.
• Delay measurement can be used to measure frame delay and frame delay variation between
MEPs.
• A local MEP must be configured for the same MA before you can use this function.
• The MEP can also make frame delay variation measurements based on its ability to calculate
the difference between two subsequent two-way frame delay measurements.
Two-Way Delay Measure
• If a MEP is enabled to generate frames with two-way delay measurement (DM) information, it
sends DM frames to a peer MEP in the same MA, and expects to receive DM frames back from
it.
• When two-way frame delay measurement are made, the transmitting MEP sends a frame with
DM request information with the TxTimeStampf (Timestamp at the time of sending a frame
with DM request information), and the receiving MEP responds with a frame with DM reply
information with TxTimeStampf copied from the DM request information, RxTimeStampf
(Timestamp at the time of receiving a frame with DM request information), and TxTimeStampb
(Timestamp at the time of transmitting a frame with DM reply information):
Frame Delay = (RxTimeStampb-TxTimeStampf)-(TxTimeStampb-RxTimeStampf)