DP4Q@TE.CC.CMU.EDU (Drew D. Perkins) (01/17/86)
We're thinking about getting a few of the Excelan TCP/IP boards/software for our 11/780's running VMS. I remember a few problems mentioned about their products before, but don't have that mail to refer back to now. What are peoples experiences with Excelan, and mostly with the current revision of their software EXOS 8043 3.2? Also, are there any archives of tcp-ip mail around? On another note, by this summer everyone at CMU will have the capability of having a dedicated 56k bps link from their homes back to CMU, if they live in one of the surrounding areas nearby. This service is going to be provided cheaply by the local telephone company. We'd like to be able use these links to extend our IP network from campus to users workstations at home. Is there any standard for IP communications over synchronous links? Does anyone know of a company that makes boards (preferable multibus) that have 8 or so syncronous links that go this speed? Hopefully the board should be capable of sending and receiving packets at a time in order for the gateway to handle the traffic. Something on the order of a Zilog SCC chip per link. Is anything like this being done anywhere else? Drew -------
tcs@USNA.ARPA (Terry Slattery) (01/20/86)
> We're thinking about getting a few of the Excelan TCP/IP boards/software > for our 11/780's running VMS. I remember a few problems mentioned about > their products before, but don't have that mail to refer back to now. > What are peoples experiences with Excelan, and mostly with the current > revision of their software EXOS 8043 3.2? Also, are there any archives > of tcp-ip mail around? I have installed Excelan's TCP/IP front-end-protocol hardware/software on several 2.9BSD Unix PDP11's at the Naval Academy. I can't comment on the VMS installation, but will try to shed some light on the implementation. Excelan makes several boards for Unibus, Q-bus, Multibus, and VME-bus. In terms of operation and capabilities, they are all identical. An on board 80186 CPU, ethernet chip, and SEEQ xcvr chip do most of the work. (The Unibus board is quite nice, Quad height, 5.5 amps total current.) When operated in link level mode, an on board PROM based kernel communicates with the host to transfer packets between the host and the wire. The driver is somewhat similar to the DEC DEUNA driver in that the host and interface communicate via a set of message buffers (organized in circular queues). In this mode, the measured throughput is 60Kbytes per second of user data from memory to memory between two Vax 780 processors with a cpu load of about 50% (BRL Vax Unix; based on 4.2BSD). When operated in front-end mode, the on board PROM module implements a skeleton operating system in which the TCP/IP network code module can execute. The net code is RAM resident and is generally downloaded to the board at boot time. (Avoid the 128Kb RAM configuration board for front-end operation; the additional memory is used for buffering to increase performance.) The host communicates with the net code via four device drivers and a set of library routines. The library implements the 4.1a network semantics which are sufficient for most applications. At the application level, they supply Telnet, FTP, rlogin, rcp, rsh, and rwho. The rlogin and telnet daemons run in the card for performance reasons. This implies that their rlogin daemon doesn't handle automatic authentication. They currently don't have an SMTP server, but I'm told that they are seriously considering one so that they have a full implementation. ARP, ICMP echo, and ICMP redirect are also supported. Gateways are supported and routes are determined by incoming ICMP packets or can be built manually with a maintenance program that they supply. (The older version 3.1 couldn't handle gateways. In fact, version 3.1 would crash if it received a packet from a host with a different net address. The 3.1a network module fixes this serious flaw. Anyone running Excelan software which says that the net module is version 3.1 should contact their supplier for the 3.1a version. ) The board status (things like ethernet collisions, etc) can be polled using another program. Sub-nets are not supported but I have mailed them some of the recent discussion and suggested that they work on it. I have measured the data rate of the PDP11 to Vax at 60Kbytes/sec for memory to memory transfers. Having ported their old 3.1 version and then beta tested the 3.2 version before its release, I found that they significantly cleaned up the code in their port to RSX and VMS. (I did find some additional bugs, but they have been reported and presumably fixed. Most of the ones I found would have appeared only on a machine like the PDP11 with its restricted addressing.) I'm quite pleased with my decision to use the Excelan cards. I've had no problems with the hardware and their software and documentation has improved significantly. Excelan has been quite helpful. Why didn't I chose CMC cards? They didn't have a shippable product at the time I needed the cards. Excelan's presence in the market seems to have been hurt a bit by the time they spent in getting the VMS/RSX ports done, but it has probably helped their code significantly. The next release is supposed to increase the performance. Now, if they just had an SMTP server for VMS, I'd buy it for our VMS machine. -tcs Terry Slattery U.S. Naval Academy 301-267-4413 ARPA: tcs@usna.arpa UUCP: decvax!brl-bmd!usna!tcs