flur@duke.gatech.edu (Peter W. Flur) (08/14/90)
We are experiencing a very interesting problem with a couple of our machines here at Georgia Tech. Two of our machines are losing between 20-30% of their packets when going through a router onto the campus network. Now for the details. My floor has its own subnet separated from the campus network by a PC router with two WD8003 ethernet cards running PC-ROUTE. Their are approximately 25 machines on the subnet including PC's, MAC's, NeXT's, Sun's, DEC's, an AT&T 3B2-1000/80, and an Intel IPSC/2 Hypercube. When communicating between two machines within the subnet, everything is fine, and no packets are lost, independent of which two machines are being used. When any PC, MAC, NeXT, Sun, or DEC machines talks with a machine outside the subnet (using ping, telnet, ftp, etc.) everything works fine and not a single packet is lost. However, the problem comes when either the 3B2 or the IPSC try to communicate outside the subnet. Each exhibits a 20-30% packet loss very consistently. This is true whether it is ping'ing or it is being ping'ed. We have concluded several things: 1) Only the two System 5 machines are having problems 2) The two machines work fine within the subnet 3) No other machine (all BSD) has problems communicating with the outside world 4) The netmask and broadcasts ARE set properly 5) The number of STREAMS and QUEUES appear to be more than sufficient 6) The cables and connectors to the two machines are fine After putting a sniffer on the subnet, we have found that the echo packets are being sent out fine, and the replies are sometimes heard on the subnet even though they appear lost. The only other significant detail that we have found was that the "time to die" for packets to/from other (BSD) machines appear in the range 200-300. The packets from the two Sys5 machines appear to be in the range 15-30. This is theoretically the maximum number of hops remaining before death, and should be well within range. Can anyone offer any good advice? Has anyone seen similar problems? Your help would be greatly appreciated. Peter ----------------------------------------------------------------------- Peter Flur, Research Engineer II Georgia Institute of Technology School of Electrical Engineering, Atlanta, GA 30332-0250 E-MAIL: flur@duke.gatech.edu PHONE: (404) 853-9355