ITEM: I4254L

Performance problem on the 128 port adapter with Cray Modems


A RS/6000 is exhibiting performance problems for remote users and
printers. This problem is occurring on two systems located at two
totally different locations.

The performance problems are indicated by poor response time to users
and printers that are attached to remote RANs. The other is the
receipt of various transmission/communications errors and 
retraining of the modems.

The following is the basic system configuration (the variations are 
in the number of remote RANs on each line only);

A RS/6000 model 580 running aix 3.2.5. 

Each line has a Cray synchronous modem through a digital leased line
to another Cray synchronous modem then a number of RANs.

Line 1 has 3 RANs and the other 2.  

The line speed is 57.6K.  

The DSU is set for internal clocking.


Set the switches of the Cray CSU/DSU modems to operate as REPEATER
mode (this can be done while in operation and without having to
repower the modems).

From the 'dpa' diagnostic software; ERR_ABSTAT, under Sync Counters,
was the indicator that lead the need for this setting.

Support Line: Performance problem on the 128 port adapter with Cray Modems ITEM: I4254L
Dated: May 1994 Category: N/A
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