boerner@ut-emx.UUCP (Brendan B. Boerner) (06/28/88)
Does anyone know if it is possible to share an Ethernet card over a PC Net network? Here's the scenario. We have an IBM PC Network v1.0 network. We would like to install an Ethernet card in one machine and then all the other machines could Telnet, FTP, etc... through that card. All info would be greatly appreciated. Thanks in advance. Brendan
kzm@TWG.COM (Keith McCloghrie) (06/30/88)
Brendan, > Does anyone know if it is possible to share an Ethernet card over a > PC Net network? > > Here's the scenario. We have an IBM PC Network v1.0 network. We > would like to install an Ethernet card in one machine and then all the > other machines could Telnet, FTP, etc... through that card. Yes, it's possible to do this with any type of LAN which provides a NETBIOS interface, by using the NETBIOS as a link layer *below* IP. The one PC with the Ethernet card then acts as an IP-Gateway. I believe there are several PD versions of TCP/IP for DOS which have a driver using a NETBIOS interface. Our commercial package (WIN/TCP for DOS R3.2) also supports this. WIN/TCP requires you to run the IP Gateway code as a regular DOS application, and thus normally requires a dedicated PC. I don't know whether this is true for the other implementations. It's probably best to have a dedicated PC anyway if you want consistent performance by the IP-Gateway code. The choice of what horsepower of machine to use for your IP-Gateway can be chosen from a price/performance perspective (if you're interested, we have some figures for this). At first glance, one questions this approach of having a session-layer protocol *underneath* IP, but the convenience is tremendous and the performance penalty is not as bad as you might think (we have seen FTP throughputs of 40-60 Kbytes/sec between a PC on the netbios network and a Sun on the Ethernet, even when being limited by a 3c501 card). In fact, performance is impacted more by the Netbios limit on datagram size rather than additional protocol processing. All the implementations I have heard of, send IP datagrams using Netbios' datagram service; this has the advantage of not having the maximum number of sessions impose any limit on connectivity, but may/will cause additional broadcast traffic (depending on how the particular datagram service is implemented). Thus, this is a good approach for occasional use by a subset of the PCs on your PC network. But if you plan prolonged use by most of your PCs, you would be better served by obtaining a multiplexing interface at a lower layer than Netbios. The trouble here is that there is little more than rumours of support for such multiplexing interfaces from many of the PC LAN vendors (e.g. 3Com, Novell). Of course, if the PCs spend all their time using TCP/IP, it would be better to connect to the Ethernet directly. Keith McCloghrie Dir, Engineering The Wollongong Group