______________________________________________________________________ news@ftp The FTP Software Quarterly Newsletter ______________________________________________________________________ Volume II, Number 2 October 1989 information at every node. Our Inside... implementation is fully compliant with RFCs 951 and 1084. Item Page Our rloginvt program now supports New Product News 1 multiple connections. This means that you can have as many as 10 Masthead 2 simultaneous connections from your IBM(R) Personal Computer(R) to Internetworking News 2 remote machines. The initial connection is numbered connection Technical Support 4 0. You can switch to other connec- tions by simply typing the PC/TCP escape character, followed by a number from 1 through 9. This makes maintaining sessions on PC/TCP(R) Version 2.04 Released remote machines as easy as toggling between screens. We've also added By Janet Marcisak a built-in ftp server to rloginvt which will allow your pc to act as Our PC/TCP Version 2 software a server while you are logged in to will be going to 2.04 this month, a remote system. Also, rloginvt and that means bug fixes, and new now does VT220 terminal emulation features. Among the new features in addition to VT100 and VT52. for 2.04 are a new BOOTP client, These features were previously only interrupt 14 support for Telnet and available in our implementation of Rlogin, multiple connection Telnet. capability for rloginvt, an enhanced ping program with many new Our ping program, traditionally options, and an updated host used to isolate trouble on a program. network, now supports ICMP error handling, and all IP options, We are introducing a bootp client including Source Route and Record in this release. This is a Route. These additions greatly bootstrap protocol facility which enhance the functionality of the allows a workstation to have utility. For example, you can use important configuration parameters, the Type of Service and Record including its IP address, set over Route options for a good look at the network. By modifying a single the best routes between you and any file on a machine running a bootp other point. The new version of server, the network administrator ping also provides the ability to can now change the configuration of dump sent and received packets in other machines - including gateways hex. and servers - without changing news@ftp _______________________________________________________________________ The updated host program allows news@ftp the DNS (Domain Name System - see RFC 1034) server to be specified, Volume II, Number 2 and can send most DNS query types. October 1989 Users can now query Domain servers for Address, Canonical name, Host Published by FTP Software, Inc. INFO, and Mail exchange records, as Editor: Nancy Connor. well as others. Communications pertaining to this newsletter should be directed to: Also new in version 2.04 is interrupt 14 support for tnglass news@ftp and rlogingl. This support allows FTP Software, Inc. you to use a wide variety of 26 Princess Street commercially available terminal Wakefield, MA 01880-3004 emulators for DEC, HP and Phone: (617) 246-0900 Tektronix(R) terminals. We have FAX: (617) 246-0901 also added 132-column support to Telex: 981970 supdup, and enhanced tnvt to allow Answerback: FTP SFTWRE UD the user to set the end-of-line Electronic mail: news@ftp.com characters and to support PrtSc and Ctrl-PrtSc for screen dumps. We've FTP Software welcomes sug- also implemented a "umask", which gestions and contributions from the user can set via the configura- readers. Submissions for the tion file, for use by both the rcp next issue of the newsletter must program and InterDrive TM. be received no later than December 15, 1989. Fixes in the 2.04 release include improvements to smtp, smtpsrv, FTP Software and LANWatch are ftpsrv, mail, tar, install, the trademarks of, and PC/TCP is a Development Kit, NetBIOS, and the registered trademark of FTP Soft- PC/TCP kernel. The kernel has been ware, Inc. enhanced to improve ARP handling, reliability and speed, and now Copyright 1988, 1989 by FTP supports the February, 1989 version Software, Inc. Permission to of IP Security options. These new use, copy, modify, and distribute features and fixes will be this publication for any purpose available as an upgrade to anyone and without fee is hereby with the PC/TCP or PC/TCP Plus granted, provided that this copy- package. Contact our sales right and permission notice department for further details. appear on all copies, the name of FTP Software, Inc. not be used in advertising or publicity pertain- Protocol Futures ing to distribution of the mate- rial without specific prior by John Romkey permission, and notice be given that copying and distribution is My home computer understands a by permission of FTP Software, lot of different protocols. Inc. TCP/IP, which also means ICMP, UDP, ARP, Telnet, FTP, SMTP. UUCP, which gives me some of the functions of TCP/IP, on a different network _______________________________________________________________________ 2 October 1989 news@ftp _______________________________________________________________________ substrate. RS232. ST506. It might database. If the data is sent over understand SCSI or ESDI. TCP or TP4, it doesn't make much difference to them, just as long as Of course, this list is a little everything they have can unfair - it's grouping bananas, communicate. To do that, the whole oranges and grapefruit. TCP, RS232 network will either have to speak and the disk controller protocols the same protocol or will have to all do different sorts of things. take advantage of translating Protocols like TCP, UUCP and OSI do gateways which allow similar pretty similar things, even though applications protocols to run on they do them indifferent ways. top of dissimilar transport Over the last few years, we've protocols (TCP, TP4, UDP, whatever) learned a lot about TCP and IP. and still interoperate. Network congestion and TCP timers have been two continual nuisances There's a lot of work being done in the TCP world, and Phil Karn, in this area already, although it's John Nagle and Van Jacobsen have not often discussed this way. There all discovered good algorithms for are mail gateways between the dealing with these problems. We've TCP/IP SMTP protocol and propri- learned how to broadcast, how to etary networking software like 3Com build a distributed host name TM 3+ TM, Novell NetWare TM and database, and presumably how to Banyan VINES(R), as well as between route packets. The technology for SMTP and the OSI X.400 protocol. building the basic TCP/IP protocol Marshall Rose's ISODE software stack is pretty well understood package allows OSI applications to now, although still not quite run on top of TCP streams, and commonplace. Much of what we've software has been developed using learned carries over to other it to gateway between OSI networks protocol stacks, such as OSI. and TCP networks and allow the same We'll see in the next few years if applications to run. Every day anybody takes advantage of this millions of pieces of electronic fact. mail and network news flow between the USENET, where they're The main reason for mentioning transmitted via UUCP, and the ST506, SCSI and ESDI is that, Internet, where they're transmitted basically, computer users don't with SMTP. care which controller interface their computer has. Users have a The network market is growing at nice (or in some cases, not so a phenomenal rate. As long as it nice, but you get the point) file is possible for unsophisticated system that sits on top of the users to continue to use the controller, and the only way they technology (and this is one of the can tell the difference between the important problems TCP/IP is controllers is through price, facing), it should not stop growing reliability and performance. until every computer in the world is connected to a world-wide Within a few, maybe five, years, network. But this network won't be network protocols should work in a speaking one single protocol. There similar way. Users don't really are strong political reasons today care how the data gets there. They for this not to happen; some want to be able to move files, organizations feel they must or login, send mail, and access their _______________________________________________________________________ 3 October 1989 news@ftp _______________________________________________________________________ must not use certain protocols. OSI maintains a complex network by is a certainty in the future, if design, the goal being to provide a for no reasons other than political diverse and complicated environment ones, but when it finally arrives for the testing of our networking (in perhaps three years), there products. By providing this will be a huge installed base of complex network as the production TCP networks, and users will be environment all employees use, FTP faced with installing new OSI Software's products can be much systems that are more expensive, more thoroughly tested than they less reliable (because they are could if we tried to maintain an less mature products) and more interesting and diverse network difficult to use (because users are only for testing purposes. accustomed to the old TCP products and these will work differently). Included here is a map of FTP As long as they can run the new Software's third floor offices. applications they want, they will The map of the second floor offices keep their TCP-based networks when is not nearly as complex, except in politically feasible and install one room (the developers only those OSI products they must. "playroom"), where all the current The networks will be made a networks have drops for the coherent whole by the use of developers to test new software on. translating gateways. Nothing is simple in networking, The computer world in 1995 will and in this environment even look quite a bit different from the something as simple as an Ethernet one now, with much more TM is not just a simple piece of sophisticated applications that wire. FTP Software runs on one don't require users to know "logical" Ethernet, but it is anything about the underlying physically several different runs network technologies and allow them and configurations. The to connect to a world-wide network "downstairs" Ethernet runs around consisting of TCP/IP, OSI, DecNET, the second floor and up into the and proprietary protocol families, machine room on the third floor. all transparent to the user. Just There, it connects through a thin- like today, when I can run ESDI and net transceiver to a "fan-out box" ST506 disk drives on my home (often referred to by the name of computer and never have to worry the DEC device of this type, called about which is which (except for a DELNI). The fan-out box has 10 the fact that one of my drives is ports, connecting several machines noisier than the other). and devices that expect to find "thick" Ethernet (and to connect to it via transceivers), instead of FTP Software's Corporate Network "thin" Ethernet, which connects to the network via T-connectors. by Stev Knowles Machines such as the VAXes and SUN connect to the fan-out box, as do FTP Software's headquarters in two additional fan-out boxes, to Wakefield is a model of complexity provide Ethernet service for the for most people designing computer offices adjoining the machine room. networks to use as a shining example of how to make a network much too complicated. FTP Software _______________________________________________________________________ 4 October 1989 news@ftp _______________________________________________________________________ Attaching fan-out boxes to each From the perspective of the users, other in this fashion is referred this is all "one" Ethernet - they to as "cascading", and is not never see the complexity involved recommended for more than two in the wiring or the hardware. levels, as we have done. The reason for this is that cascading Some of the complexity does help to more levels introduces too many - the repeater will isolate the two problems with timing for the thin Ethernets if one goes bad or hardware to work correctly. There is open. This allows the people on is also a repeater connected to the the third floor to be unaware of fan-out box, connecting the the fact that the people on the upstairs and downstairs thin second floor have broken their Ethernet segments. Ethernet. More importantly though, it allows us to test software and The thin Ethernet on both floors hardware in less than ideal is wired into the offices in the conditions, allowing us to following manner. You will notice (hopefully) improve the robustness in the diagram that there are of the product when dealing with straight runs between offices, and less than ideal networks. "loops" on adjoining walls. We decided to install thin Ethernet in But, as you all know, all the the building walls, and run "local world is not an Ethernet. FTP loops" inside the offices. This Software currently has in allowed us to easily expand the production use several other thin Ethernet, without having wires networking topologies, and current dangling down walls. A thin plans call for more introductions Ethernet drop comes down inside a in the near future. The router wall, and terminates in a wall connects the IBM Token ring (4 plate with two BNC connectors. The megabit), the STARLAN (1 megabit), top connection is "up-stream", or the ProNET-10(R), and the Ethernet closer to the machine room. If you together. The sales department were to put a terminator on the uses the 1 megabit STARLAN, and the upper connection, you would isolate administrative department uses the the rest of the network from IBM Token Ring for their every day everything past you on the wire. communications uses. A 10 megabit The bottom BNC connector is "down- STARLAN in the playroom is stream" from you, or going away connected to the thin Ethernet for from the machine room. use by the developers. The 10 megabit STARLAN is connected via When you remove the plate from transceiver and the 10 megabit the wall in one office and look in STARLAN cards are connected to a the wall, you find the plate for fan-out box in the same way the the other office is right across Ethernet fan-out box is used. from you, and the bottom connector of one plate is attached to the top The ProNET-10 is used by one of connector of the other (which is the VAXes, and there are drops in downstream depends on which plate the offices adjacent to the machine is closer to the machine room). As room. FTP Software connects to the you can see, the upstairs Ethernet Internet through a 9600 Baud serial starts at the repeater (marked Rpt line to Cambridge, MA, and we also on the illustration) and ends in have two internal SLIP connections the office closest to the stairs. _______________________________________________________________________ 5 October 1989 news@ftp _______________________________________________________________________ - one into the support office, and We try to keep at least one of one into a developers office. This each board that we support in complexity allows for constant production use, to allow for easier traffic on all of these networks testing of new releases, and to try and for us to observe PC/TCP and pinpoint places in which the interacting with itself and other current drivers need additional TCP/IP implementations across links work. with widely diverging speeds, from 9600 baud to 10 megabits per As you can see, we have made our second. Constant work is being environment more complex in an done on the product to increase effort to make the product better, performance across networks and and to make your work easier by between different TCP/IP constantly enhancing our products implementations. to make them robust and easy to support. Things are constantly In the near future, we will be changing here, and new systems are installing a 16 megabit IBM Token always appearing on the networks. ring, along with an IBM Ring As FTP Software grows and offers Bridge. We are looking to add a more products and services (like system to one of the networks other 3+Open TM and NetWare than the Ethernet (we are compatibility), the networks here considering an IBM RT on either the will continue to grow and become 4 or 16 megabit rings), as well as more complicated. Just be glad you purchasing some other machines don't have to deal with it. which have networking code which is divergent from the standard code being shipped from Berkeley for LAN Packet Demultiplexing their version of UNIX. We are also or adding drops for the IBM Token How You Can Run All Those Rings and STARLAN in the support Different Protocols on One Cable office, and are planning to add at least two more routers (one for by James VanBokkelen linking internal nets, and one for a new, 56 KBit link to the Most LAN administrators know Internet). quite a bit about LANs, such as how data is broken up into packets, and We are also running applications how each host has a hardware which have been developed outside address by which it is known to of FTP Software to look at ways of others. Many could outline the improving the performance of the basic mechanisms of Ethernet or network for these applications. Token Ring, and lay out the wiring Not too surprisingly, things like X for an office. However, if faced windows and databases use the with the question "We've got this network in a much different fashion Brand X LAN cable all over the than Telnet or FTP Software does. place, can I connect my two Brand Y We currently have a Banyan VINES machines to it?", they may well be file server, and are in the process at a loss for an answer. of bringing up Novell NetWare and 3+Open file servers for production As long as hardware interfaces use. for whatever LAN standard is in use (Ethernet, 802.5, STARLAN, etc.) are available for the new machines, _______________________________________________________________________ 6 October 1989 news@ftp _______________________________________________________________________ and they run the same version of How does this multiplexing work? the same network protocol (NetWare, When you look at how data moves DECnet, TCP/IP or whatever), over the LAN media, you find that compatibility is usually ensured all LAN technologies break each (unless one implementation has machine-to-machine data flow up bugs). However, the reality of the into a series of separate messages, situation is that this isn't always or packets. Each packet has a the case. One reason is that source and destination address, and different manufacturers all too framing to separate it from other often support different LAN packets. This allows many protocols - another department different hosts to share a common might choose a different LAN O/S wire to communicate, without the for their PCs, or bring IBM overhead and cost of setting up compatible machines into a separate circuits between each pair previously all-Mac environment. of hosts. It also makes it easier Another reason is that LAN to design higher-level protocols protocols are frequently that guarantee delivery of data specialized - the original even in the face of transmission installation might be using a PC errors. Thus, the first level of LAN O/S to share files and LAN multiplexing is based on printers, and the new users might packets, and individual machine need to use TCP/IP over the LAN to addresses. The recognition of log in to a mini-supercomputer and hardware addresses and run linear programs or CAD framing/unframing packets is almost software. They can't use the LAN always done in hardware, to reduce O/S because its developers didn't the load on the host CPU. include remote login in their design. To implement the second level of multiplexing requires some way of Fortunately, the designers and telling protocol A packets from implementors of most of the major protocol B packets. At first, this LAN standards had this issue in might not seem necessary, unless mind. LAN cabling is expensive, some of the machines want to speak and LAN bandwidth is usually much several different protocols at larger than any single host could once, because hardware addresses use, so it is a natural reaction to would seem to ensure that packets make the resource as widely shared from protocol A are only received as possible. The first level of by machines that speak A. However, sharing allows many different almost all LAN protocols make some clients and servers using protocol use of broadcast packets, sent to a A to use the same cable at the same special hardware address which all time (multiplexing). The second, machines receive. This is most which is designed into all but a often done to locate machines whose few LAN standards, allows the hardware address isn't known, or to machines speaking protocol A to locate a server of some sort. share the cable with others using Since hardware addresses are protocols B and C, and even allows usually assigned arbitrarily, as sophisticated machines to use sev- interfaces are manufactured, and eral different protocol families at change when interfaces are once. replaced, broadcast protocols are very attractive compared to long _______________________________________________________________________ 7 October 1989 news@ftp _______________________________________________________________________ tables of hexadecimal numbers on same amount of space (16 bits) for each LAN node. demultiplexing information as DIX Ethernet, but the IEEE chose to There are several different divide it up differently. The second-level demultiplexing first byte is the Destination mechanisms: one of the earliest, Service Access Point (DSAP), and and still the most widely used, was the second is the Source SAP that selected by DEC, Intel and (SSAP), where SAPs roughly Xerox when they defined Ethernet. correspond to Ethertypes. Because a Each DIX (or Bluebook) Ethernet number of bits have been reserved packet has a 16-bit "Ethernet to define special SAPs, only 24 packet type" field in the header unique values are available for immediately after the destination demultiplexing different standard and source addresses. All XNS protocol formats. packets have an Ethertype value of 0x600, IP is assigned Ethertype The 802.2 header is normally 0x800, DECNet Maintenance & either 3 or 4 bytes long, depending Operations Protocol uses 0x6002, on which IEEE Logical Link Layer and so forth. Every DIX Ethernet Control method is in use. LLC1 protocol, from widely used public uses 3 bytes, and provides a simple specifications like IP to private datagram service. LLC2 uses 4, and protocols used by a single product provides reliable link-level from a single manufacturer, must delivery of messages. The LLC2 have a unique number assigned to scheme is attractive to designers it, so it is a good thing that of small-scale LAN protocols, there are 65,000 available. because it can greatly simplify a Ethertypes were initially allocated lightweight transport layer. How- by Xerox, but the IEEE has taken ever, LLC2 is much less useful in over that function.1 internetworks, where many different LAN and WAN segments are connected The second most widely-used by packet routing nodes. Most demultiplexing mechanism is the implementors of large-scale IEEE packet header format specified protocols have chosen to use LLC1 in 802.2. 802.2 headers are in use for its lower overhead, since the on 802.3 (IEEE Ethernet), 802.4 presence of different media types (Token Bus), 802.5 (IBM-type Token and routers requires a separate Ring) and FDDI networks. In each end-to-end reliable delivery case the 802.2 header immediately mechanism even if LLC2 is supported follows the physical-layer header, on all links for all paths. which varies according to the media in use. The 802.2 header uses the Because the number of available SAPs is so small, the IEEE has been very reluctant to assign values to ____________________ protocols it feels are unimportant, 1. Regrettably, neither organiza- or restricted in scope. While tion has ever made the list of several vendors have simply assigned types public, which some- appropriated SAP values for their times complicates Ethernet debug- private protocols, others have made ging. Several different lists of use of the Sub-Network Access known Ethertypes exist, maintained Protocol within 802.2. This is by various commercial and educa- identified by a reserved SSAP/DSAP tional network sites, but they are necessarily incomplete. _______________________________________________________________________ 8 October 1989 news@ftp _______________________________________________________________________ value, and adds a 3 byte Organiza- standard but discarding the rest as tionally Unique Identifier to the inefficient has been known to cause normal header. The TCP/IP conforming implementations to community obtained an OUI of report an error for every packet 0x000000, and defined it as being they receive. Perhaps the most followed by a 16-bit DIX Ethertype, common instance of self- in order to provide access to any centeredness is abuse of broadcast existing Ethernet protocol on all facilities, producing systems that 802-type LAN media. The eight don't scale up well. Frequent bytes of demultiplexing information broadcasts are ok in a cozy little this represents is the largest in community of 20 personal computers, common use today. but not when you have 400 nodes representing 5 departments on the Other LAN media may use 802.2 cable, particularly when someone headers, or type fields ranging suggests a per-packet charge to from 8 to 32 bits, but the "allocate overhead costs better". principle is the same; soon after a packet is received, low-level This presents a dilemma to the software can look at some well- LAN designer or administrator - if defined part of the packet header all of the different protocols to find out which protocol it is abide by the rules, you can get a destined for. If this host has no lot more return out of an expensive higher-level software to deal with cabling job, improve a particular packet, it should be interdepartmental communication and discarded quickly, so as not to use specific networking protocols waste CPU cycles. for specific jobs. If they don't, you get headaches, and unhappy Of course, as everyone who has users. ever used a computer knows, they are rarely perfect. In the LAN My opinion is that even if you world, there are certainly careless can segregate each function right vendors, ignorant vendors and self- now, it won't last. Somebody will centered vendors. The careless need to do their next CAD project kind can be recognized when their on a graphics workstation instead software hangs or misbehaves when of a PC, but they'll want to send confronted with a packet it doesn't their finished drawings to the PC understand, or when a machine users' plotter. Purchasing, crashes and jams the LAN cable Manufacturing, Engineering and until it is powered off. The igno- Accounts Payable will want to share rant didn't fully understand the an inventory database. Somebody standard they implemented, and send will notice the cost of the tape packets that violate the drive to back up each individual specification, or ship hardware minicomputer. Given this, any that can only talk with each other resource that helps you design, and not with other vendors' cards. purchase, install and maintain large, heterogeneous networks is Self-centered vendors are very valuable. Books, courses, sometimes the hardest to cope with. conferences and seminars each have Using an unallocated packet type or their place, but the most powerful SAP value can lead to protocols resource is other LAN-using sites. that won't share a cable or an If you can get access to one of the interface. Implementing part of a _______________________________________________________________________ 9 October 1989 news@ftp _______________________________________________________________________ national news/mail/conference networks, either commercial, like CompuServe or The Source, or non- commercial like Usenet, do so. Find the LAN-related forums with high signal-to-noise ratios and post your questions, answering in turn when others want information you have. In addition, or if you can't do it electronically, check out local computer groups, go to vendors' user-group meetings, ask salesmen for references and develop your own network of resources. The diversity of the LAN-using community practically ensures that someone else has experience with the hardware or software combination that you're interested in. ____________________________________ PC/TCP and FTP Software are regis- tered trademarks, and InterDrive is a trademark of FTP Software, Inc. VINES is a registered trademark of Banyan Systems, Inc. IBM and IBM Personal Computer are registered trademarks of Interna- tional Business Machines Corpora- tion. NetWare is a trademark of Novell, Inc. ProNET-10 is a registered trademark of Proteon, Inc 3Com, 3+ and 3+Open are trademarks of 3Com Corporation. Ethernet is a trademark of Xerox Corporation. _______________________________________________________________________ 10 October 1989