Two schemes - prefix partitioning and interval partitioning - are proposed to improve the performance of dynamic IP router-table designs. While prefix partitioning applies to all known dynamic router-table designs, interval partitioning applies to the alternative collection of binary search tree designs of Sahni and Kim [S. Sahni et al., (2004)]. Experiments using public-domain IPv4 router databases indicate that one of the proposed prefix partitioning schemes - TLDP - results in router tables that require less memory than when prefix partitioning is not used. Further significant reduction in the time to find the longest matching-prefix, insert a prefix, and delete a prefix is achieved.

Two schemes - prefix partition and interval partition - are proposed to improve the performance of router-table design. Significant reduction in the time to find the longest matching-prefix, insert a prefix, and delete a prefix is achieved.

Internet (IP) packet forwarding is typically done by finding the longest prefix in a router table that matches the packet's destination address. For W-bit destination addresses, the use of binary tries enables us to determine the longest matching prefix in O(W) time, independent of the number n of prefixes in the router table. New prefixes may be inserted and old ones deleted in O(W) time also. Since n/spl Lt/2/sup W/ in real router tables, it is desirable to develop a data structure that permits longest prefix matching as well as the insertion and deletion of prefixes in O(logn). These three operations can be done with O(logn) cache misses using a B-tree data structure [S. Suri et al., (2001)]. However, the runtime (including operation cost and cost of cache misses) is not O(logn). In this paper, we develop a data structure in which prefix matching, prefix insertion, and deletion can each be done in O(logn) time. Experiments using real IPv4 routing databases indicate that, although the proposed data structure is slower than optimized variable-stride tries for longest prefix matching, the proposed data structure is considerably faster for the insert and delete operations.

Waldvogel et al. [ACM SIGCOMM, 1997, 25-36] have proposed a collection of hash tables (CHT) organization for an IP router table. IP lookup can be done with O(log l/sub dist/) hash-table searches, where l/sub dist/ is the number of distinct prefix-lengths (also equal to the number of hash tables in the CHT). Srinivasan and Varghese [ACM transactions on Computer Systems, Feb:1-40, 1999] have proposed the use of controlled prefix-expansion to reduce the value of l/sub dist/. The algorithm of [V. Srinivasan, 1999] does not minimize the storage required by the prefixes and markers for the resulting set of prefixes. We develop an algorithm that minimizes storage requirement but takes O(nW/sup 3/ + kW/sup 4/) time, where k is the desired number of distinct lengths, n is the number of prefixes, and W is the length of the longest prefix. Also, we propose improvements to the heuristic of [V. Srinivasan, 1999].

Srinivasan and Varghese (see ACM Trans. Comput. Syst., p.1-40, 1999) have proposed the use of multibit tries to represent routing tables used for Internet (IP) address lookups. They propose dynamic programming algorithms to determine the strides of optimal multibit fixed-stride and variable-stride tries. We improve on these algorithms by providing alternative dynamic programming formulations for both fixed- and variable-stride tries. While the asymptotic complexities of our algorithms are the same as those for the corresponding algorithms of Srinivasan and Varghese, experiments using real IPv4 routing table data indicate that our algorithms run considerably faster. Our fixed-stride trie algorithm is two to four times faster on a SUN workstation and 1.5 to three times faster on a Pentium IV PC. On a SUN workstation, our variable-stride trie algorithm is between two and 17 times faster than the corresponding algorithm of Srinivasan and Varghese; on a Pentium IV PC, our algorithm is between three and 47 times faster. An added feature of our variable-stride trie algorithm is the ability to insert and delete prefixes taking a fraction of the time needed to construct an optimal variable-stride trie "from scratch".

A data structure is developed that permits one to find longest matching prefixes as well as to insert and delete a prefix in O(log n) time, where n is the number of prefixes in the router table. Experimental results using a real IPv4 routing database are also presented.

In this paper, we provide the communications processing module in the Telephone Network Access Subsystem (TNAS) of the Advanced Communications Processing System (ACPS). We define communication tasks and related resources such as several queues which are executed in real-time operating systems, and we implement the procedures for processing user information. Through traffic modeling and simulation, the performance of the service processing board assembly (SPA) is evaluated in terms of system utilization and buffer size. The ACPS should accommodate various public networks such as the public switched telephone network (PSTN), packet switched data network (PSDN), frame relay network, and asynchronous transfer mode (ATM) network. The communications module proposed in this paper could be used in the interface between the SPA and the high speed network adaptor(HSNA) of other network interface subsystems.