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EVDO signaling link interrupted even we are able to ping the BTS & BSC IP from NE40E Router

Publication Date:  2013-07-11 Views:  53 Downloads:  0
Issue Description

EVDO signaling link interrupted  from BTS to BSC and after giving reset to BCIM, link came up.

218 HSIA sites are down for delhi (Kindly support packet capture and NE40 logs collection required for end to end tracing of the issue from BSC to BTS.)


Handling Process

During the outage time we observed that  there was alram occured at BTS and BSC end and there was no alram found on the router end.

But at same time we are able to ping the BTS and BSC end IP's and learnig the MAC address of the equipment also.

Ping result is attached below with file name "Site 644 in testing 01-46 AM" .

There after we decided to capture the TCP packets at our NE40E end port .

During the  MUX switchover, and the TCP request was sent by BTS, received by BTS END MUX, but not received BSC, and it also not received by NE40 during , thus we can say the TCP request was lost somewhere between NE40 AND BTS END MUX.  


Root Cause

Base on the analysis of BTS110 AND BTS103, we found that BSC cannot receive the BTS TCP request after switching over MUX, so DO signaling link interrupted. BTS has sent the TCP request and received by BTS END MUX, but NE40 and BSC cannot receive it, only after giving reset to BCIM, TCP request was received by BSC, DO signaling link re-connected. So we are strongly suspecting the transmission between NE40 and BTS end MUX are abnormal, which will lead to DO link interruption and it cannot restored automatically.



Change the TX device


Need to check the Third part TX equipment why it is droping the TCP packets