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FAQ-The Two Test Nodes Are in the Same Ring. The Short Path Is 300 km and the Long Path Is 1500 km. When the Services Traverse Along the Long Path, They Traverse Many More NEs. In This Case, Whether the Service Transmission Rate on the Long Path Is Affected Or the Rate Still Can Be Set to 100 Mbits

Publication Date:  2012-08-12 Views:  121 Downloads:  0

Issue Description

The two test nodes are in the same ring, and the short path is 300 km and the long path is 1500 km. When the services traverse along the long path, they traverse many more NEs. In this case, whether the service transmission rate on the long path is affected, or the rate still can reach 100 Mbit/s when related parameters are set to certain values. 

Alarm Information


Handling Process

The service transmission rate on the long path cannot reach 100 Mbit/s. In the long path, the delay of an NE does not exceed 20 us (equivalent to four credits over an 8 km distance), which can be ignored.
The FC service is connection-oriented and it needs to wait for response. Therefore, the rate decrease is more significant when the delay is much longer, as shown in the following figure: 


In addition, the test result depends on how the tester tests the rate. If the user tests the transmission rate by simulating the transmission with software, the rate can reach 100 Mbit/s by setting related parameters (block size, I/O parallel traffic). If the user performs the test by copying data of the server and disk array, the rate cannot reach 100 Mbit/s. 

Root Cause