Table of Contents
Advertisement
OC3port Plus
User Manual
Cell Delay Variation Tests
The OC3port Plus calculates Cell Delay Variation (CDV), which is a
quantification of how cells clump together as they travel on a particular VPI/VCI.
The tester performs two types of CDV tests:
•
A 1- point CDV
•
A 2- point CDV
This section shows you how to set up and run these tests.
1-point CDV Test
A 1-point CDV test is concerned with the early arrival of cells, which indicates
that the transmit source is in violation of its traffic contract.
During this test, the OC3port Plus captures a sample of cells and assigns each cell
a received time stamp. The arrival times of cells in the capture buffer are then
compared with an "ideal" arrival time (which is the inverse of the PCR) and a
resultant one-point CDV value is derived.
If the result is positive, the cells sampled arrived early, which indicates clumping
and possible excessive usage above the contract rate by the transmit source.
After each analysis of the buffer's contents, the buffer is emptied and allowed to
re-fill so that the test can continue.
Setting Up a 1-point CDV Test
The OC3port Plus does not have to be used as the cell source. The
operation of this test depends only upon the CDV PCR value and
receive filter selected when the test is run.
If, for example, you use RECEIVE FILTER 3 to perform the test, the
OC3port Plus analyzes only cells that have headers matching this
filter. The "ideal" arrival time for each cell is the inverse of the value
specified for CDV PCR..
6-66
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
Note
Advertisement
Table of Contents
