For some time, the networking community has assumed that it is impossible to do IP routing lookups in software fast enough to support gigabit speeds. IP routing lookups must find the routing entry with the longed matching prefix, a task that has been thought to require hardware support at lookup frequencies of millions per second.We present a forwarding table data structure designed for quick routing lookups. Forwarding tables are small enough to fit in the cache of a conventional general purpose processor. With the table in cache, a 200 MHz Pentium Pro or a 333 MHz Alpha 21164 can perform a few million lookups per second. This means that it is feasible to do a full routing lookup for each IP packet at gigabit speeds without special hardware.The forwarding tables are very small, a large routing table with 40,000 routing entries can be compacted to a forwarding table of 150-160 Kbytes. A lookup typically requires less than 100 instructions on an Alpha, using eight memory references accessing a total of 14 bytes.

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We propose an architecture where clients can make advance reservations through agents responsible for advance admission control. The agents allocate resources in the routers just before they are needed for packet forwarding. In this paper we show that network resources can be shared between immediate and advance reservations without being pre-partitioned. The admission control schemes for immediate and advance reservations still operate with little interaction.Admission control decisions for immediate reservations use information about resources to be allocated for advance reservations in the near future. An important parameter in the admission control algorithm is the so called lookahead time, i.e., the point at which we actually start making resources available for approaching advance reservations by rejecting immediate requests. In our model, preemption of immediate reservations is made in cases where the admission control cannot make resources available through rejection of immediate requests. The risk of preemption can be varied by changing the lookahead time when making immediate admission control.We explore, with simulations, the effects of providing advance reservations according to this model. The results show the cost in terms of resource utilization, rejection probability and preemption probability.

Wireless is becoming a popular way to connect mobile computers to the Internet and other networks. The bandwidth of wireless links will probably always be limited due to properties of the physical medium and regulatory limits on the use of frequencies for radio communication. Therefore, it is necessary for network protocols to utilize the available bandwidth e ciently. Headers of IP packets are growing and the bandwidth required for transmitting headers is increasing. With the coming of IPv6 the address size increases from 4 to 16 bytes and the basic IP header increases from 20 to 40 bytes. Moreover, most mobility schemes tunnel packets addressed to mobile hosts by adding an extra IP header or extra routing information, typically increasing the size of TCP/IPv4 headers to 60 bytes and TCP/IPv6 headers to 100 bytes. In this paper, we provide new header compression schemes for UDP/IP and TCP/IP protocols. We show how to reduce the size of UDP/IP headers by an order of magnitude, down to four to ve bytes. Our method works over simplex links, lossy links, multi-access links, and supports multicast communication. We also show how to generalize the most commonly used method for header compression for TCP/IPv4, developed by Van Jacobson, to IPv6 and multiple IP headers. The resulting scheme unfortunately reduces TCP throughput over lossy links due to unfavorable interaction with TCP's congestion control mechanisms. However, by adding two This work was supported by grants from the Centre for Distance Spanning Technology (CDT), Lule a, Sweden, and Ericsson Radio Systems AB. simple mechanisms the potential gain from header compression can be realized over lossy wireless networks as well as point-to-point modem links. Checksum could be computed from payload and values of decompressed header, but is always included in the compressed header as a safety precaution. Grey fields of full header stored as compression state. Generation field ensures correct matching of compressed and full headers for decompression.