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The Uploading and Downloading Rates of the MxU 5651 Are Low Because the Settings of the FTP Server Such as the Buffer Are Incorrect

Publication Date:  2012-07-25 Views:  122 Downloads:  0
Issue Description
OLT version: MA5600V800R105C33B050.
MxU version: MA5600 V800R305C03B026 (including the patches MA5600 V8R305C03B026SPH001 and MA5600 V8R305C03B026SPH002).
Networking description: The FTP server is connected to the softswitch through the MxU 5651. The client is connected to the VDSL modem, which is connected to the VDSL line. The VDSL line then is connected to the FTP server.
Fault symptom: The FTP rates cannot meet the required 100 Mbps. 
Alarm Information
Handling Process
A. Adjust the configurations of the server.
1. Set the transmit buffer and the receive buffer to be the sizes as large as possible on the Advanced tab page of the FTP server.
2. Set the maximum uploading rate and the maximum downloading rate to be as large as possible on the General tab page.
B. To rectify the fault of the host, do as follows:
1. Check whether the patches are installed or are running successfully after you disable the rate restriction function. The MA5600 V8R305C03B026SPH002 patch is used to solve the problem wherein the FTP rates cannot meet the requirements. Note that you must activate the port again after the patch installation.
2. If the patches fail to be loaded or cannot run, enter the diagnosis mode or run commands on the command line interface to disable the rate restriction function. To disable the rate restriction function, run the following commands:
MA5651G(diagnose)%%debugging lswdrv bcm-cli
BCM.0> _port mode=set pbm=ge0 FlowCtrl=true
BCM.0> _port mode=set pbm=fe8 FlowCtrl=true
C. Do not use the FAST mode.
D. Modify the size of the sliding window according to the requirements.
Restart the server to validate the modification. In addition, the sizes of the sliding windows of both the server and the client must be modified, because the sizes of the TCP sliding windows are negotiated. 
Root Cause
A. The server is faulty.
B. The host is faulty.
C. In the FAST mode (that is, when No Protection is selected for impulse noise protection downstream in the case of the VDSL channel profile), the packet loss ratio is high, and the measurement result is inaccurate. Therefore, do not use the FAST mode.
D. Use the Wopti Utilities to modify the size of the sliding window if necessary during the test. The larger the sliding window of Windows, the larger the rates.
Note: The sliding window here is the window negotiated through the TCP protocol. 
1. The larger the sliding window, the larger the rates. For details, see the attachment.
2. Ensure that the FTP settings are correct.
3. You can check whether the size of the sliding window based on the TCP negotiation meets the requirements of the test by capturing packets with the Ethereal software. 4. When testing the rates, start the task manager and click the Networking tab to check whether the rate of the network port that you use is smooth. If the rate jitters, it indicates that certain packets are lost.
Note: The rate obtained by using the preceding method is more accurate. Do not view the rate on the command line interface.