lih@probe.att.com (08/14/90)
Can anyone give a description or refer me to some documentation on COLAN (Central Office Local Area Network)? Thanks. Andrew Lih lih@probe.att.com
"Marc T. Kaufman" <kaufman@neon.stanford.edu> (08/15/90)
In article <10885@accuvax.nwu.edu> lih@probe.att.com writes: >Can anyone give a description or refer me to some documentation on >COLAN (Central Office Local Area Network)? DAVID systems has a PBX cum Ethernet which has been sold to Ameritech as a CO LAN. There are Ethernet jacks on the back of the phone sets, and any Ethernet capable equipment can be plugged in. Once the data gets to the PBX switch, it is turned into real Ethernet. "Real" Ethernet devices on coax can also be used with the system. Switches can be connected via coax, Ethernet, or (multiple) T-1 spans. Ethernet packets can be gatewayed between switches on any of these links. The CO LAN concept has all voice traffic directed to Centrex (thus removing the voice features of the PBX), while letting the PBX connect Ethernet packets within itself, and, via links to the CO, to other DAVID switches (hence: CO LAN). Marc Kaufman (kaufman@Neon.stanford.edu)
Robert Halloran <rkh@mtune.att.com> (08/17/90)
In article <10885@accuvax.nwu.edu> lih@probe.att.com writes: >Can anyone give a description or refer me to some documentation on >COLAN (Central Office Local Area Network)? CO-LAN (at least the version I know about) is a data-over-voice network offered by some of the RBOC's. The user takes a VDM (voice-data mux), plugs it into the phone line, then connects the terminal/PC/whatever and the phone set into the VDM. The unit modulates the data stream above the voice band and carries it to the CO, where it is broken back out by another VDM there and typically fed into a Datakit VCS data switch for access to host services. The VDM can handle input to 19.2K baud. The user must be within three "wire-miles" of the CO for the VDM to be able to successfully drive the line. Our group (w/ NJ Bell) manages a CO-LAN for AT&T employees in four CO's of Monmouth county where the density makes it sensible (there must be a threshold number of potential users to justify parking the data switch at the CO). I know of at least one other CO-LAN for AT&T employees in northern NJ (the Murray Hill area). Bob Halloran Internet: rkh@mtune.dptg.att.com UUCP: att!mtune!rkh Disclaimer: If you think AT&T would have ME as a spokesman, you're crazed.
schoff@uu.psi.com (Martin Schoffstall) (09/13/90)
Intecom at one point in time was also marketing this capability on their PBX, as I remember there was a bandwidth limit <10Mbps on the cable plant to the phone. In addition an Ethernet Jam et al was propogated to each "phone". In general a real mess, this was circa 1986. I'd be interested in hearing on some of the technical details of the DAVID systems on the list. Marty