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Technology Stocks : Ciena (CIEN) -- Ignore unavailable to you. Want to Upgrade?

To: Stash who wrote (5669)	11/30/1998 8:56:00 AM
From: Frank A. Coluccio	Respond to of 12623

>>You gave me a lot of information to digest and ideas to think about. << Glad to have been a help, Stash. >>CIEN/SR...straight line tech.(should have asked point A to point B) found it in the TLAB info.<< In wide area optical network terms, two fundamental topologies exist. Ring and Linear. Linear [the Point to Point ( A ---> B) that you referenced], can only be protected by redundant paths using automatic protection switching techniques. The Ring, of which there are four or five fundamental types to differentiate from, based on the number of strands and [or] wavelengths used as one classification, and whether the line itself is being switched or whether (virtual) paths are being switched as the second. These ring types use the now-familiar self-healing wrap-around technique. Digital Cross Connects are often tandemized into a mesh throughout an operating company's territory, and they use SONET rings as the fundamental means of transport. But they define user networks in the maps contained within them, and these do not follow the straightforward restoration techniques discussed above. Rather, DCSs have stored configuration maps, and in compound or complex networks (which usually exist in multi-location user networks) they depend on software defined measures to rebuild path tables. This is what takes such a long time as evidenced in the T failure you mentioned, and indeed in last week's MCI failure that knocked out parts of MAE West. I would venture to guess that the rings themselves in each of these failure scenarios were satisfactorily rebuilt almost instantaneously. Instead, it was probably the digital cross connect mesh that took the longest time to rebuild. And in many cases, with activity being what it is today, I would also venture to guess that the carriers are not on top of the contingency map preparedness as they ought to be. FWIW. Additional topologies include interlocked rings, stars, modified stars, meshed, tree and branch, etc. depending on the venue and type of service being provided, and the degree of survivability dictated. Frank C.