2: Characteristics of Gigabit Networks

Advances in communication rates exceed the ability of a single source to fully utilize a gigabit WAN channel with existing deterministic protocols. Parallel communication describes a method for reducing latency by managing indeterminism and increasing channel utilization, given a surplus bandwidth-delay product. It involves a nondeterministic state mechanism, with a modified protocol interface. Recent advances in communication rates have (and will) outpace the ability of a single source to effectively utilize channels. This surplus bandwidth, in the form of an excess bit latency (i.e., bandwidth-delay product), provides an opportunity for increased channel utilization. Here we present one paradigm for using such an opportunity , called Parallel Communication. Parallel Communication extends the channel functions, to permit more responsive user service in domains with high bit latency, through increases in the effective channel utilization. Parallel Communication specifies the ways in which sets of communication are managed together, and describes a modification of our existing protocol paradigms that can better utilize links with high bit latencies. Gigabit networks are characterized by a high band-width-delay product (we prefer bit latency, the latency 1. measured in bits, rather than time), and by the relationship of this product to the messages exchanged. In Figure 1, the equivalences between various speed and scale networks are shown. The bit latency characterizes the protocol operation [9]. Since a gigabit LAN has a bit latency equivalent to a 100 kilobit WAN (ignoring topology issues), TCP/IP (which has worked on WANs up to 1.5 Mbps) should suffice. All existing protocols incur several trips worth of latency during connection setup. Existing protocols also attempt to pipeline the data transfer during the connection as well. Here we are considering only the mid-stream utilization (ignoring setup) and including conventional pipe-lining. By these measures, existing protocols, which work in WANs up through 45 Mbps, will suffice in LANs through 100 Gbps (and MANs through 10 Gbps) (see the 45 Mbps WAN rate line in Figure 1). FIGURE 1. Network equivalences. (diagonal dashed lines specify bit latency equivalence) Bit latency has exhibited three phases of evolution. In the first phase, characterized by NCP in the ARPANET in 1970-1980 [2], the channel bit latency was small compared to the average computer buffer size. TCP became prevalent in 1980 as the bit latency increased, and approached the average file size [6]. TCP is a sliding-win