Why I use a Mac, anno 2006 3720

krw

SBS had originally been formed equal partners with IBM, Comsat, and Aetna ... for doing computer-to-computer data transmissions. A big issue was that the communication group had strangle hold on computer-to-computer data transmission with SNA ... and SNA had extremely low tolerance for satellite delay transmission (as well as scaleup in bandwidth that satellites frequently brought).

Because of the heavy influence that the communication group had blocking anything but straight sna for computer-to-computer transmission ... SBS was effectively forced into migrating to other markets ... and eventually got into voice transmission. They were in the public long-distance market (as well as heavily installed internally within the corporation).

major plant sites had these big 10meter dishes that were c-band running T3 (44mbits-sec) transmission. because of corporate security standards the data aggregator (or data aggrevator), full bandwidth T3 encrypter as developed and deployed. voice channels were then suballocated out of the T3 channel. couple posts mentioning data aggrevator application--early data communications application--early data communications triode) production dates?

early in the deployment there is this story where they tried to do double-hop 56kbit connection between STL and Hursley (STL to satellite, down to the east coast, up to atlantic satellite and down to the UK). They put up standard VNET on both ends and everything flowed fine. They then switched to a JES2-SNA at both ends and no traffic flowed at all. The person in charge was severely SNA indoctrinated ... and explained that obviously that there must be significant transmission errors which the advanced SNA error detection was able to recognize ... and that the primitive VNET handling just wasn't detecting. Geosync satellite are about 22000 miles, double hop round trip then is 8*22000 ... 176,000 miles with signal traveling at 186,000mps ... plus a little processing delay at the remote site works out to about one second elapsed time. recent post mentioning JES2 networking

Eventually SBS was dissolved, the phone-long-distance stuff sold off to MCI and the birds sold off to hughes.

part of my hsdt project

involved custom designed tdma earth stations using transponder on SBS-4 (Ku band) for doing (non-sna) computer-to-computer transmissions. Part of this involved gracefully doing compensation for satellite propogation delay and bandwidth scaleup. recent post mentioning sbs-4 flying on 41-d

other recent posts making mention of SNA and the communication group with an IP address to the mainframe Off-Mainframe Server (Was: Using Java in batch on z-OS?) (Was: Using Java in batch on (Was: Using Java in batch on z-OS?)