Applying 4-regular grid structures in large-scale access networks
4-Regular grid structures have been used in multiprocessor systems for decades due to a number of nice properties with regard to routing, protection, and restoration, together with a straightforward planar layout. These qualities are to an increasing extent demanded also in largescale access networks, but concerning protection and restoration these demands have been met only to a limited extent by the commonly used ring and tree structures. To deal with the fact that classical 4-regular grid
... uctures are not directly applicable in such networks, this paper proposes a number of extensions concerning restoration, protection, scalability, embeddability, flexibility, and cost. The extensions are presented as a tool case, which can be used for implementing semi-automatic and in the longer term full automatic network planning tools. (J.M. Pedersen), a.patel@cnds. ucd.ie (A. Patel), email@example.com (T.P. Knudsen), obm@control. aau.dk (O.B. Madsen). † Average average distance: the average average distance is obtained by taking the average of d(u, v) over all pairs of nodes usv, where u, v2N. † Worst-case average distance: the worst-case average distance is obtained by taking the maximum over all nodes u of the average of d(u, v) for all nodes v, usv, where u, v2N. † Diameter: the diameter is obtained by taking the maximum of d(u, v) over all pairs of nodes usv, where u, v2N. † Cost: since the representations of structures abstract from specific physical conditions such as node equipment, transmission technologies, bandwidth, and line ducts and lengths, it is hard to estimate the cost of a structure as such. We use either the number of lines or the average node degree to indicate the cost.