roes.phcoms@seri.philips.nl (Aloys Roes) (06/05/90)
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,
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