Brocade 6910 Ethernet Access Switch Configuration Guide (Supporting R2.2.0.0) - Manual (Page 1070)

1014 Brocade 6910 Ethernet Access Switch Configuration Guide
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Connectivity Fault Management
Transmitting Periodic Loss-Measure Messages
Use the Administration > CFM (Configure Periodic Loss Measure) pages to configure periodic
transmission of loss-measure messages. These messages can be used to measure near-end and
far-end frame loss.
CLI References
• “CFM Commands” on page 517
Command Usage
• Both the source and destination MEP must be configured for the same MA before transmitting
loss-measure messages.
• A MEP cannot transmit periodic loss-measure and on-demand loss-measure messages at the
same time.
• Results of periodic loss measure testing will be recorded in the system log after completion of
each full cycle.
Single-Ended Loss Measure
• Follow these steps to transmit periodic single-ended loss-measure (LM) messages:
• Use the “Add Single-Ended LM Group” page to create a messages attribute group which
defines the overall message cycle, the duration of the transmission, the interval between
message transmissions, and the timeout to wait for a response.
• Use the “Configure Single-Ended LM” page to bind a message attribute group to a local
MEP, and designate the target MEP.
• The settings of an existing attribute group cannot be modified. First delete the group, and then
redefine the attributes. To delete an attribute group, unbind it from any local MEPs by setting
the Group Index parameter to “none” on the “Configure Single-Ended LM” page, and then
deleting the group from the “Show Single-Ended LM Group” page.
• Single-ended loss measurement (LM) is carried out by sending periodic loss measurement
request (LMM) PDUs to its peer MEP and receiveing loss measurement reply (LMR) PDUs from
its peer MEP to carry out loss measurements. The LMM PDU used for carrying single-ended
loss measure information is transmitting at an interval of 100 ms.
To perform loss measurement, a MEP periodically transmits LMM frames with the following
information element:
• TxFCf– Value of the local counter TxFC1 at the time of LMM frame transmission.
Whenever a valid LMM frame is received by a MEP, an LMR frame is generated and
transmitted to the requesting MEP. An LMR frame contains the following values:
• TxFCf – Value of TxFCf copied from the LMM frame.
• RxFCf – Value of local counter RxFC1 at the time of LMM frame reception.
• TxFCb – Value of local counter TxFC1 at the time of LMR frame transmission.
Upon receiving an LMR frame, a MEP uses the following values to make near-end and far-end
loss measurements:
• Received LMR frame's TxFCf, RxFCf and TxFCb values and local counter RxFC1 value at
the time this LMR frame was received. These values are represented as TxFCf[t
c
],
RxFCf[t
c
], TxFCb[t
c
] and RxFCl[t
c
], where t
c
is the reception time of the current reply frame.