Timing clock caused poor Ascend showing

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.