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Knowledge Base

Packet loss in the receive direction of Ports 3 and 4 on the SL91EM6T or SL91EM6F

Publication Date:  2012-07-25  |   Views:  223  |   Downloads:  0  |   Author:  Mohamed Saber  |   Document ID:  EKB0000527267

Contents

Issue Description

A large number of error frames are generated in the receive direction of ports 3 and 4 of the SL91EM6T or SL91EM6F, resulting in packet loss or even service interruptions.

Alarm Information

Null

Handling Process

There are two methods to solve the problem:
Method 1: Reset the register.
Step 1: Query the register by issuing the :datamod-debug:bid,"bd drv get-reg 0x48" command in the Navigator.
The query result is 0x1f8fc7e3.
Step 2: Set the register value to 0x1F86C7E3 by issuing the :datamod-debug: bid,"bd drv set-reg 0x48 0x1F86C7E3" command in the Navigator.
Method 2: Configure services on port 5 or 6 instead of port 3 or 4.

Root Cause

1- Checking the performance for Ethernet services configured for port 3 or 4 of the SL91EM6T or SL91EM6F, the RXBBAD (indicating the count of error frames) continuously increases. 
2- After contacting with R&D, they confirmed that crosstalk occurs between signals received and transmitted over the SSSMII bus in the DX2122 chip on SL91EM6T/ SL91EM6F boards. As a result, the holding time in the receive direction 
may be greater than 1 ns (designed value for the chip). Consequently, error frames are generated, resulting in packet loss or even service interruptions. 

Suggestions

None.