acy@faron.icd.abnet.COM (Adnan Yaqub) (10/08/88)
We are having a problem communicating to Sun 3/60 workstations running Sun OS 3 via TCP/IP with bridge boxes and ascii terminals. About once every five minutes output from the Sun stops for a period of about seven seconds. We performed a test to try and isolate the problem (and assign blame) using a network analyzer and a simple echo loop and this is what we discovered happens during a `freeze': Sun sends packet 1 Bridge acks packet 1, window = 46 Sun sends packet 2 Bridge acks packet 2, window = 45 Sun sends packet 3 <five second pause> Sun sends packet 4 Bridge acks packet 3, window = 45 It seems to me that what is happening is that the Bridge box is dropping packets every now and then. What I don't understand is why the Sun waits five or so seconds before sending the next packet? The window is still open. Shouldn't the Sun immediately send the next packet? If it did so, the Bridge would see that is lost a packet and everything could recover much quicker. (Although Bridge should fix their box. The packet obviously was delivered to them. We got it on the network analyzer.) Could this be a bug in Sun's silly window avoidance code? (Does Sun have silly window avoidance code? We don't have source code to check.) -- +-----------------------------------------------------------------------------+ |Adnan Yaqub ...[cvedc|cwjcc|decvax|masscomp|mrmarx|pyramid|uunet]!abvax!acy| |Allen-Bradley Company 747 Alpha Dr. Highland Hts. OH 44143 USA (216) 646-4409| +-----------------------------------------------------------------------------+