Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!masscomp!think.com!zaphod.mps.ohio-state.edu!sdd.hp.com!spool.mu.edu!uunet!telebit!brian From: brian@telebit.com (Brian Lloyd) Newsgroups: comp.dcom.lans Subject: Re: NetBlazer Keywords: NetBlazer Message-ID: <1991Apr6.073416.21710@telebit.com> Date: 6 Apr 91 07:34:16 GMT References: <4369@zeus.sbi.com> Sender: news@telebit.com Distribution: usa Organization: Telebit Corporation; Sunnyvale, CA, USA Lines: 61 Nntp-Posting-Host: napa.telebit.com Well perhaps I am a bit biased but I can answer the question about how the NetBlazer works (I designed it) and I am posting this message from my home running rlogin through a NetBlazer connection. The typical time to establish a connection is 25-35 seconds. The hosts requirements RFC requires hosts to wait 1 minute before timing out. This is usually not a problem but if you have a host that does not wait the requisite period of time, just restart the operation. The line will certainly be up in time for the command to operate the second time around. As for buffering, each outbound interface has a queue. As system administrator you get to select the number of datagrams that may be queued at any one time. The default value is 8 datagrams on the queue. If the link is not up all incoming packets are queued up to the maximum number of packets. Any additional packets are discarded. The NetBlazer is an IP-based device so it has no way of knowing how many sessions are passing through it (with IP it is possible for datagrams to take different paths through the network). What the NetBlazer does do is keep track of packet activity. A timer is reset every time a d'gram passes through an interface. If the timer times out the NetBlazer commands the modem to hang up. The timer may be set to anything from 1 second to 65535 seconds but the default value is 180 seconds. Since my connection to our network at work is a local call, I keep my timeout set to 600 seconds (10 minutes). What happens if the link times out while you are still "connected" (you got up for a cup of coffee)? Nothing really. If you are doing TELNET or rlogin, your next keystroke will generate a d'gram and the NetBlazer will dial and reconnect. You simply have to wait for about 25 seconds while the NB reconnects. One last feature that comes in handy if you are in a hurry to get something done. The NetBlazer support inverse multiplexing. If you have more than one modem you may elect to have the NetBlazer bring up more than one connection to the destination NetBlazer. In that case you get the throughput of two (or more!) modems. And while we are on the subject of throughput, I typically see a throughput of 1.6K bytes/second per modem when sending binary files with FTP. Text files benefit greatly from the V.42bis compression in the modem and I usually see 2.5 KB/s to 3 KB/s throughput. The NetBlazer also supports Van Jacobson's IP/TCP header prediction/compresion algorithms when running SLIP or PPP. This greatly reduces latency and makes interactive activities (TELNET, rlogin, rsh, etc.) more palatable. Well, I hope I have answered your questions to your satisfaction. Feel free to write or call. Brian Lloyd, WB6RQN Telebit Corporation Network Systems Architect 1315 Chesapeake Terrace brian@napa.telebit.com Sunnyvale, CA 94089-1100 voice (408) 745-3103 FAX (408) 734-3333 -- Brian Lloyd, WB6RQN Telebit Corporation Network Systems Architect 1315 Chesapeake Terrace brian@napa.telebit.com Sunnyvale, CA 94089-1100 voice (408) 745-3103 FAX (408) 734-3333