The rapid growth of the Internet has led to numerous changes to the underlying technologies. In the early days, host names and their corresponding IP addresses were kept in a flat text file ("
"), updated weekly by the Network Information Center at SRI International. In the mid 1980s it became clear that this method of name/address mapping would not scale, and a new distributed lookup mechanism was designed and deployed. This new method, known as the
Domain Name System
(DNS), has proven successful even in the face of millions of Internet hosts.
Another result of Internet growth is the potential for depletion of the IP Version 4 (IPv4) 32-bit address space. In the early 1990s, this became a matter of great focus for the Internet Engineering Task Force (IETF). The "short-term" fix for this problem was to abandon the original concept of A, B and C address classes and introduce
Classless Interdomain Routing
(CIDR), which consumes addresses in a much more efficient manner-that is to say, more slowly. Address consumption has also been slowed by the use of
Network Address Translation
(NAT) and private address space. Predictions for when the Internet will finally run out of IPv4 addresses varies. The long-term solution is to replace IPv4 with IPv6 which uses 128 bits for addressing.
One area of Internet growth that is currently causing some concern among ISPs is the growing size of the routing table that each router participating in the
Border Gateway Protocol
(BGP) must keep in memory. Our first article, by Geoff Huston, is a detailed look at this problem. Geoff takes an historical look at the BGP routing table, and discusses ways to address some of the issues.
In our March 2000 issue, Geoff Huston wrote an article entitled "Quality of Service-Fact or Fiction?" that discussed the prospects for achieving QoS on an Internet-wide scale. In this issue, Bill Stallings looks at QoS in the LAN environment, which is generally easier to control than the Internet as a whole. LAN QoS has been standardized in IEEE 802.1D which is the subject of this article.
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â€”Ole J. Jacobsen, Editor and Publisher