Timing clock caused poor Ascend
showing
By
Network World, 3/23/98
Ascend Communications, Inc. says it may have isolated what was causing
its soon-to-be-released MAX 6000 to perform poorly in our tests. The
company says a timing clock on an inactive WAN port was left enabled
when it should have been turned off. That could account for the poor
showing, especially on download throughput.
The problem occurred after Ascend technicians advised us to move a PRI
line from one WAN port to another to rectify initial problems our testers
had with the unit dropping calls.
Ascend says leaving clocking enabled on the inactive port threw off the
timing on all the other WAN ports, leaving the entire unit with an inaccurate
clocking source. The company says it has run tests similar to ours and has
gotten twice the download rates we did.
The situation came about early on in Ascend's pre-allotted time in the lab.
Each vendor was given a set amount of time to complete tests and
troubleshoot any problems encountered during testing.
Our testers requested Ascend's help in diagnosing why the MAX 6000 was
dropping calls coming into the first WAN port. In an attempt to solve the
dropped calls problem, Ascend upgraded the unit with the latest version of
firmware and had us move a PRI connection from the first WAN port to
the fourth, suspecting the first WAN port was at fault.
With 60 clients calling into the machine, we only needed three WAN ports
to do our testing. Once the fixes were applied, things went more smoothly
but the unit fell just shy of completing our test, which called for 60 clients to
be simultaneously transferring files.
Concerned that the unit was unable to complete the test, Ascend kept
working well past deadline to uncover the problem's cause. It was during
that post- deadline examination that the clocking issue came to light.
Ascend asked us to retest the unit with the clocking disabled but we did not
have the time. However, our testers were able to do trial runs with a few
clients once the clocking on the inactive port was disabled. The unit's
performance appeared to improve but it still dropped calls. Without a full
retest, our testers can't say for sure whether turning the clock off would
bring performance up across the board.
However, Ascend has contracted with XXCAL Testing Laboratories, Inc.,
the same company we worked with, to rerun the test at its own expense.
Results from that test will be posted on XXCAL's Web site at
www.xxcal.com. |
