Tim, I would like to elaborate at some future time on some of my experiences with I-R shots, but for the moment I can only state that in very close proximity arrangements, the success rate that we had with them in downtown Manhattan were superior to metallic T1s.
In fact, at one point I consulted to a client who had a campus comprised of four buildings tied together with American Laser Systems I-R/free space equipment in a star configuration [two buildings on Broad Street, one at Hanover Sq. and one on Water Street] that were operational and highly viable for a number of years, when the client decided to put in T1s from NYNEX, at the time.
The cutover to the telco T's took place over a weekend and all was well at first, until they began encountering some elusive or otherwise intermittent problems on the metallics, at which point we decided to cut back to the free space window shots, thus relegating the metallics to backups.
But I would caution that... these results were achieved under almost ideal conditions, where the longest shot was approximately 1400 feet, and the other two were on the orders of 300 feet, and 500 feet, respectively. And yes, ticker tape contingencies, unavoidable pigeon flutterings and window washer scheduling, were all a part of this network architects' defined practices in the quality assurance manual used by the Network Control Center. FWIW.
In case you are wondering, we were running highly critical treasury and other applications over these links, supporting unframed (from the standpoint of T1 framing) mainframe Hyper-channel links to remote IBM controllers and other processors under bus and tag switching arrangements, at the time. The links were were DES encrypted.
These links have since been removed, and I now have some of the transceiver guns and other arifacts associated with mountings and conroller devices adorning my offices on Broadway.
Regards, Frank Coluccio |
