roes@phcoms.seri.philips.nl (Aloys Roes) (06/06/90)
I posted this one before but did not see it on the net. Sorry if you get it
twice.
Please help us in solving the following problem:
We have a TCP/IP wide area network in place with 9.6, 14.4 and 64Kbps
lines. For the communication equipment we have standardized on cisco TCP/IP
routers.
Most lines show quite good performance however a few lines have reasonable
to high error counts. These error counts are stable and seem independent of
network load. With these error statistics we asked our telecommunication
people to improve the line quality. Of course they doubted whether the
errors were real. Therefore they started with bit-error-rate tests. These tests
show that the lines are 'perfect' i.e. no single bit or block error in 24
hours. They used different bit patterns but did not get any error.
The next thing we did was to install a PC with a 64K serial interface in
parallel to the cisco router on both ends of one 64K link. The program in
the PC analyzes the packets and monitors the link. And this is where
we really get confused. The PC also finds errors. However these errors are
of a different class and different amounts.
The link that we monitored has an average of 6000 to 10000 errors per day
on one end and a few dozens of errors on the other end. We are now focused on
the end with the high error count;
According to the cisco the errors are mainly frame errors. The PC reports
mainly CRC (or FCS) errors.
Can anyone help us getting this sorted out? What is the best way to tackle
this problem. Is there any equipment that we can put on the line and realy
trust the test-results? Has anyone faced such a problem before? Please respond
to me directly. I will post a summary,
Thanks in advance,
Aloys Roes, Philips Components, Building BC-136, | Tel. : + 31 40 72 30 62
P.O.Box 218, 5600 MD Eindhoven, The Netherlands | Email: roes@seri.philips.nl
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regards,
Aloys Roes, Philips Components, Building BC-136, | Tel. : + 31 40 72 30 62
P.O.Box 218, 5600 MD Eindhoven, The Netherlands | Email: roes@seri.philips.nl