Dmr Reception; Two-Way Eth-Dm Statistics; Two-Way Eth-Dm Frame Counts - Juniper JUNOS 10.1 - CONFIGURATION GUIDE 1-2010 Configuration Manual

DMR Reception

When an MEP receives a valid DMR, the router that contains the MEP measures the
two-way delay for that frame based on the following sequence of timestamps:
TI
1.
TxDMM
Time at which the initiator MEP transmits a two-way ETH-DM DMM frame to
the responder MEP.
TR
2.
RxDMM
Time at which the responder MEP receives a DMM frame from the initiator MEP.
TR
3.
TxDMR
Time at which the responder MEP transmits a two-way ETH-DM DMR) frame,
associated with a specific DMM frame, to the initiator MEP.
TI
4.
RxDMR
Time at which the initiator MEP receives a DMR frame from the responder MEP.
A two-way frame delay is calculated as follows:
[TI – TI ] – [TR
RxDMR TxDMM
In other words, frame delay is the difference between the time at which the initiator
MEP sends a DMM frame and the time at which the initiator MEP receives the
associated DMR frame from the responder MEP, minus the time elapsed at the
responder MEP.
The delay variation is the difference between the current and previous delay values.

Two-Way ETH-DM Statistics

The router that contains the initiator MEP stores each set of two-way delay statistics
in the ETH-DM database. The ETH-DM database collects up to 100 sets of statistics
for any given CFM session (pair of peer MEPs). You can access these statistics at any
time by displaying the ETH-DM database contents.

Two-Way ETH-DM Frame Counts

Each router counts the number of two-way ETH-DM frames sent and received:
For an initiator MEP, the router counts the number DMM frames transmitted,
the number of valid DMR frames received, and the number of invalid DMR
frames received.
For a responder MEP, the router counts the number of DMR frames sent.
Each router stores ETH-DM frame counts in the CFM database. The CFM database
stores CFM session statistics and, for interfaces that support ETH-DM, any ETH-DM
frame counts. You can access the frame counts at any time by displaying CFM
Chapter 44: Configuring ITU-T Y.1731 Ethernet Service OAM
– TR ]
TxDMR RxDMM
Ethernet Frame Delay Measurements Overview
743