kermit@BRL.ARPA (Chuck Kennedy) (11/04/87)
This evening, network performance was somewhat less that "optimal". The results are shown in the table below and represent the results of running ping for at least 2 minutes to check out round-trip packet delay and packet loss to various selected hosts. All tests were run from the host brl-vmb.arpa. The first interesting finding is that performance on the Milnet is quite good. Even a cross-country connection from brl-vmb.arpa on the East coast to nprdc.arpa on the West coast had 0% packet loss, an average round-trip time of 348 ms and a maximum round-trip time of 1418 ms. By comparison, a cross-country connection to ucbvax.berkeley.edu exhibited a 61% packet loss, an average round-trip time of 9064 ms and a maximum round-trip time of 22514 ms. Why the large discrepancy between responses from these two hosts? One possibility that looms is the Arpa-Milnet gateway. Running simultaneous pings to both sides of dcec-milnet-gw.arpa (BRL's default Arpa-Milnet gateway) reveal large packet losses. Admittedly, the simultaneous pinging can influence the packet loss level. However, even non-simultaneous pings to the different addresses of the gateway indicated large packet losses. One other revealing test is a simultaneous ping to the Arpa side of the gateway and to ucbvax. Packet loss just to the gateway was 40%, increasing to just 44% for packet loss to ucbvax. Average round-trip time to the gateway was 5743 ms while round-trip time to ucbvax was 7448 ms, almost 2 seconds longer. This would seem to indicate that much of the problem is in the gateway. There is probably an additional problem between the gateway and ucbvax since average round-trip time cross-country via Milnet is only 348 ms. Sample time: 2315-2340 on November 3, 1987 Ping was run for at least 2 minutes to gather the results below: Internet # hostname min/avg/max loss ---------- --------------------- ------------- ---- 26.2.0.29 aberdeen-mil-tac.arpa 33/348/6566 1% 26.0.0.45 ardec-mil-tac.arpa 99/208/3614 0% 26.0.0.50 amc-hq.arpa 114/148/748 0% Non-simultaneous 26.0.0.104 dcec-milnet-gw.arpa 6651/19174/32842 76% 10.7.0.20 dcec-milnet-gw.arpa 518/4452/13966 30% 26.0.0.104 dcec-milnet-gw.arpa 433/3408/14547 41% Simultaneous 26.0.0.104 dcec-milnet-gw.arpa 433/4020/15399 36% 10.7.0.20 dcec-milnet-gw.arpa 599/4724/21784 50% 26.3.0.3 nprdc.arpa 333/442/1418 0% 10.2.0.78 ucbvax.berkeley.edu 1948/9064/22514 61% Simultaneous 10.7.0.20 dcec-milnet-gw.arpa 548/5743/24565 40% 10.2.0.78 ucbvax.berkeley.edu 933/7448/22865 44%