ARPANET Routing Algorithm Improvements

Abstract

BEFin COMPLETO Yom I. REIPORT NUM69R I. GOVTlr A GI, S NO 9. &1aeCPIENT'S CATALOG NUMO4EI .3RE)RNUN Ar-Aol-33'? 4. TITLE (IN.d"dile). TYPE OF REPORT a P"O@ COVERED *-Report No. 3940 Bolt Beranek and Newman Inc.

OSPF Version 2

“…For this reason, it is important to note that links between transit vertices must be bidirectional in order to be included in the above tree. It should also be mentioned that more efficient algorithms exist for calculating the tree; for example, the incremental SPF algorithm described in [Ref1]. The set of next hops to use for the destination may be recalculated several times during the shortest-path tree calculation, as shorter and shorter paths are discovered.…”

“…In fact, there are incremental algorithms that allow an implementation to recalculate only a portion of a single area's shortest path tree [Ref1]. However, these algorithms are beyond the scope of this specification.…”

A route pre-computation algorithm for integrated services networks

“…Both components together lead to E * (O(Dijkstra) + V * log(V)) . Generally, the upper bound for fully connected graphs of Dijkstra's algorithm is given by V2 [25], [this upper bound is very pessimistic] . So O(algorithm) = E * V2 + E * V * log(V) .…”

“…The performance of the algorithm can be improved by application of different methods for incremental computation of spanning trees when edges are removed. Work on this topic has been started very early [25] and gained focus recently again [26-291 . " The algorithm can easily be extended to work with directed graphs .…”

Reducing complexities of the distributed max‐flow and breadth‐first‐search algorithms by means of network synchronization

“…The algorithm referred to in [6] as Algorithm G3 is one of the basic asynchronous BFS algorithms. It is essentially the shortest path routing algorithm used in the original ARPANET network [7] where all link weights are equal. Its communication and time complexities are C = O(lV1') and T = O(lVl), respectively.…”