Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!julius.cs.uiuc.edu!apple!portal!cup.portal.com!cec From: cec@cup.portal.com (Cerafin E Castillo) Newsgroups: comp.protocols.tcp-ip Subject: Re: SLIP modem autodialing and idle line detection Message-ID: <36633@cup.portal.com> Date: 7 Dec 90 01:57:17 GMT References: <1852@hawk.nstn.ns.ca> Distribution: na Organization: The Portal System (TM) Lines: 74 While the virtual circuit, IP addressing, and idle time may be critical points to your application(s), I would have to agree on the speed of SLIP. Currently, most SLIP/CSLIP/PPP are run via high-speed modems and hardwired links which are limited to the abilities of the serial I/O port in combination with the phone line or copper wire bandwith. 18 Kbps is the fastest currently possible on the phone line (Telebit PEP) but V.32 (9600) is the most responsive to interactive full-duplex sessions. 38.4 Kbps is quite suitable via hardwired connection. But for a WAN, its got to be modems or special services (leased, 56k, T1). The NetBlazer introduces two ways in which one can attain high throughput while using SLIP/CSLIP/PPP. A 56 kbps V.35/RS-232 interface board can be integrated into the NetBlazer and used with Synchronous PPP to talk to another NetBlazer OR the Cisco, Novell, and 3COM PPP Routers. INVERSE MULTIPLEXING is yet another way to gain a high thorughput, BUT over phone lines! Inverse muxing is a way of taking two or more modems (TELEBIT V.32s) and dividing an IP data stream amongst them. Thus, you multiply your bandwith by the number of modems used and their throughput: 6 modems x 9600 bps (V.32) = 57.6 kbps (approx.) This can be done using SLIP/CSLIP/PPP, BUT requires two NetBlazers (1-mux -> 2-demux) and multiple phone lines and modems to accomplish the connection. The modems are assigned as a group and the high-water mark is the maximum number of modems in the group. Thus, if your file transfer or X-Windows session does not require all 6 modems, only the number needed to get the job done (as calculated by the NetBlazer) are used. The other modems remain on standby or are used on a first-come; first-serve basis, depending on the number of overlapping groups given access to the modem pool. Any contension for modems yield a 'Network Unreachable' error. The modems go on and off hook as more or less bandwith is needed throughout the connection. I understand that Inverse Muxing has been tested with up to 24 modems so far, with reliablity and good throughput (remember TCP/IP overhead over serial lines...). These two features are meant to provide ease of dialbackup or Point-of- Presence (POP) applications in WANs. If your 56 kbps goes down, several modems pick-up and replace the high-throughput connection (metrics are used to keep traffic on 56 kbps channel until modems are needed; OSPF is on the way in the NetBlazer - '91). These features will also serve quite well for a dial-up IP service provider. The nice part about this is that the modems are auto initialized and configured for the connection in the virtual circuit. This leaves the Sys or Net Admin to worry about IP addresses and and network topography rather then hacking SLIP drivers and configuring modems to auto-dial. RIP makes this box go well with your routers, gated, and routed systems and SNMP MIB I and II provide good network support. NCSA Telnet, KA9Q [NOS] (PPP.12), freeware SLIP for Suns, as well as VJ CSLIP, FTP Software Inc. PC-205 for DOS, and InterCon InterConnect II for Mac; were all tested with this box doing SLIP/CSLIP/PPP. I used them all quite a bit and found no problems. I am waiting for the virtual circuit capabilities to be built into these applications in order to enjoy this connectionless IP environment from my Mac/PC/UNIX sys at home to my office NetBlazer. It'd be nice to see this in a few X-Windows terminals, as well. We'll see what the future brings for these product. For more information, please feel free to e-mail or phone, I'm a TELEBIT distributor, as well as an ex-Telebit (NetBlazer) employee. (Sorry for the salesy plug, but I do have this info and carry the products...;-). =============================================================================== Cerafin E. Castillo || //\\ ||\\ || Network Consultant || //__\\ || \\ || Los Altos Los Altos Networks || // ---\\|| \\|| Networks 340 Second St. #6 ||___// \ | \ | Los Altos, CA 94022 (415) 941-8031 UUCP: {apple,sun,uunet}!portal!cup.portal.com!cec INTERNET: cec@cup.portal.com "...No hay mal que por bien no venga..." =============================================================================== Brought to you by Super Global Mega Corp .com