dave@lsuc.on.ca (David Sherman) (06/06/90)
We have a fairly complex communications setup, part of which includes: Users in Ottawa Memotec and other cities --- X.25 PAD --> packet-switched network --> X.25 PAD at host in Administrative machine #1 <--- Gandalf PACX <--- Toronto | v Gandalf 309 short-haul modem <-- 4-channel multiplexor | leased line to second office 2 blocks away | Gandalf 309 ----> 4-channel ---> Administrative short-haul modem multiplexor Machine #2 In other words, the PACX allows users in our remote offices to sign on to either administrative machine, one of which is in the machine room with the PACX and the other a couple of blocks away. It all works fine (and in fact I'm simplifying a lot of detail). Due to increases in out-of-town staff, we need to increase both the number of ports on our Memotec PAD (from 16) and the number of PACX channels. As an alternative to simply upgrading, we're looking seriously at a new box from Gandalf called an "Access Server", which combines the functionality of PAD and PACX. (Anyone have experience with this?) Our original plan was to also replace the 4-channel multiplexors (Gandalf PIN 9106, quite old) with two 8-channel ones (Gandalf Mini-Mux), since more ports are needed into Admin Machine #2. The Access Server becomes cost-effective if we can use the Memotec PAD, which will now be surplus, as a multiplexor rather than buying two Mini-Muxes. The Access Server, with its X.25 capability, would play the role of multiplexor in place of the 4-channel mux at the machine room end. Now, my question: I've used PADs and X.25 quite a lot, but always over a packet-switched network, where packet turnaround time is slow, and packets are typically sent when full, on a timeout or (from an interactive user) on a CR or other control character. If we want this PAD to work as a multiplexor, however, we'll have to configure it to forward a packet on every character, with no delays. Otherwise UNIX tty echo won't work, and of course screen-based editors would be useless. On a local leased line supported by short-haul high-speed modems (19200 bps), can a PAD packet and depacket X.25 fast enough to make it work transparently as a multiplexor? Any comments appreciated. David Sherman Computer Education Facility The Law Society of Upper Canada 20 Queen St. West, 34th floor Toronto, Canada M5H 2N6 (416) 947-3466 (at LSUC); (416) 889-7658 (most days) -- Moderator, mail.yiddish { uunet!attcan att utzoo }!lsuc!dave dave@lsuc.on.ca