mills@huey.udel.edu (11/30/86)
Folks, For those of you that can stroke a Sun, I have a bunch of scatter diagrams showing some interesting characteristics of the ARPAnet, MILnet and the gateways between them. For comparison, I also have scatter diagrams showing a typical ARPAnet path in December, 1983. The diagrams can be FTPed from UDEL2.UDEL.EDU (binary/image mode) and lit using the Sun screenload program. Each diagram is about 40K octets in length and is stored in a file with BIT extension. Most were made using fuzzballs either connected directly to the ARPAnet or MILnet or behind a fast, lightly loaded gateway. Each diagram shows delay versus length and was constructed using ICMP pings in the manner described in RFC-889. These data should be considered only a sample of Internet characteristics, so it is possible that collection of additional data may reveal new surprises. Following are some brief comments, which should be read with Sun in hand. Files ISID.BIT and VENERA.BIT show a typical transcontinental path via ARPAnet. The former reflects the path as of December 1983, while the latter the path as of today. Regression lines are also shown on the diagrams. Note the two-step delay characteristic for ISID, which was due to the ARPAnet design at that time which used different allocation strategies for single and multiple packet messages. The two-step characteristic is also apparent for VENERA, but not as pronounced. Note the increased dispersion in the contemporary data, which is hardly surprising to any of us. Files ARPMIL.BIT, MILARP.BIT and ISIA.BIT show typical Internet paths between hosts on ARPAnet and MILnet via an ARPAnet/MILnet gateway. ARPMIL shows an ARPAnet path, MILARP a MILnet path and ISIA a combined path. The effect of network load is clearly apparent when compared with VENERA. What bothers me here is the huge dispersion at the lower packet lengths. A more clever routing algorithm would show dispersion roughly proportional to length. Files ARPNIC.BIT and MILNIC.BIT show typical ARPAnet (ARPNIC) and MILnet (MILNIC) paths between east-coast hosts and the Network Information Center host, which is connected directly to both nets. The effect of additional trunking capacity on MILnet is obvious. Comparison with ARPMIL and MILARP show that maybe that capacity is in the wrong place. I have an extensive set of diagrams also for NSFnet and some of its tributaries. It would be interesting to extend these measurements to other paths, including SATNET, WIDEBAND and SURAN hosts. All it takes is a convenient fuzzball and a vampire tap or alligator clips. Dave -------