RULES OF THUMB NETWARE LINK/X.25 Link/X.25 is part of the NetWare Link family of internetworking products. The Link product family provides transparent and reliable LAN-to-LAN connectivity for NetWare networks using asynchronous, X.25 and high-speed synchronous communications lines. Each product takes maximum advantage of the reliability, security, performance and routing features of the NetWare operating system. Link/X.25 is Novell's multi-point member of the Link family which connects multiple NetWare LANs through a private or Public Data Network (PDN). To aid you in configuring Link/X.25 for optimal performance, reliability and ease of use, we asked our engineers to recommend components for the router installation. We have also included some helpful general information regarding LAN-to-LAN links in a wide area networking environment. Here is what the experts have to say: WIDE AREA NETWORK CONFIGURATIONS The optimal LAN-to-LAN configuration is a blend of products that best serve the economic and performance requirements of the organization. Many organizations will require a combination of several NetWare Link products to meet specific needs. Studies show that users typically need to perform a number of activities over the internetwork, including: FILE TRANSFER - Uploading and downloading files, for example, between branch offices. ELECTRONIC MAIL - An increasingly used tool for communications in large, geographically distributed organizations. HOST ACCESS - Most large organizations need to be able to provide users with access to key applications on mini or mainframe based systems. DIRECT FILE ACCESS - Real-time manipulation of data on a remote workstation, file server or mainframe; for example, accessing a centrally maintained database. NETWORK MANAGEMENT - The ability to monitor the activity of separate local area networks and to distribute software and other LAN utilities from a centralized location. NETWARE LINK PERFORMANCE CONSIDERATIONS Each type of data access across the link must be analyzed carefully to determine the numbers of users transferring data and/or accessing files, as well as the number of links that must be crossed in order to get the data. These issues must also be weighed against performance requirements and cost considerations. These topics are discussed in the Novell report, Internetworking Your NetWare LANs (479-000046-002), available from your NetWare reseller, Novell sales office, or by calling the Product Information Center for Communication Products (800-221-6402 x4410). GENERAL NETWARE LINK REQUIREMENTS Link products require a number of separate components for establishing the LAN-to-LAN link, including the router software, communication adapter, data communications equipment (such as modems, CSU/DSUs, or data switches) and the telecommunications service (such as a standard phone line, X.25 line or leased line). The correct evaluation of user needs and selection of the above components is necessary for cost-effective and optimal data communications. Customers purchasing NetWare Link products should work closely with the telecommunications and/or MIS personnel to identify the types of services already available in the organization to determine if new services or devices are required. THE LINK/X.25 ROUTER As a general rule of thumb, NetWare Link/X.25 is ideal for organizations with existing connections to X.25 private or public data networks, or where X.25 is needed for international access. Electronic mail, host access, centralized network management and occasional file transfer applications work well over Link/X.25. Intensive applications that require availability of high data bandwidth, such as direct file access (including all database applications) and large file transfers, will require faster wide area network connections such as T1. The X.25 protocol overhead used by Link/X.25 and the delay introduced by the PDN can slow response time. At any given data rate, a point-to-point connection such as Link/64 or Link/T1 provide higher throughput. SOFTWARE CONFIGURATION > External Router Only Link/X.25 operates as a real mode NetWare external router, so you will need a workstation separate from the NetWare file server to act as the router PC. The router attaches to either a CSU/DSU or full-duplex synchronous modem, which in turn connects to the X.25 line. > Nondedicated or Dedicated Router? While there are good reasons to run a non-dedicated router (one that combines the router with a regular user workstation), we do not recommend this configuration. If, for any reason, the user should reboot the system or hang the system while running a particular DOS application, all of the users dependent upon the link could lose important information and hours of productivity. Used properly, however, a non-dedicated router can be useful for running network management programs, such as the ECSTATUS program provided with Link/X.25, which provides information on router status. Recommendation: If running the router as a non-dedicated router, leave it in 'console' mode except when running a network management application. > NetWare Version Link/X.25 works with NetWare version 2.10 and higher. Note that a router created from one version of NetWare 2.10 or higher (including NetWare 386) can accommodate SPX/IPX packets from any other router running NetWare v2.0a and above, including NetWare 386 v3.x. However, print services may be disrupted if you mix NetWare v2.0a with later releases of NetWare. > DOS Version Link/X.25 is designed to use PC-DOS 3.x. > NetWare Link Compatibility Link/X.25 can coexist in the same router machine with Link/64 and Link/T1 but not with NetWare Link/Async or another Link/X.25 router. Of course, all NetWare Link products can coexist on the same network or internetwork. > Optimal X.25 Configuration Parameters Link/X.25 can accommodate packet sizes from 128 to 1,024. We recommend a packet size of 1,024 for optimal performance. Setting a window size of 7 is also recommended. These parameters may be defined by the PDN upon subscription. APPLICATION NOTES > Accessing IBM SNA Mainframes With a NetWare SNA Gateway installed on your central LAN, NetWare users can run the NetWare 3270 LAN Workstation software on remote LANs to access their SNA host across the X.25 links. This eliminates the need for QLLC or NPSI (IBM Network Packet-Switching Interface) software. > Macintosh Connections NetWare for Macintosh will only work at speeds of 19.2 kbit/s or faster. AppleTalk timeouts may occur if WAN delays are encountered going through multiple packet switches. The NetWare router (previously known as a bridge) routes only SPX/IPX packets. Therefore, a NetWare for Macintosh Service Protocol Gateway must be installed at the same site as the Macintosh workstations to convert AppleTalk protocols to SPX/IPX before crossing the router. The NetWare for Macintosh value-added processes (VAPs) run in protected mode and Link/X.25 runs in real mode, so the VAPs need to be installed in another external router or file server in order to operate correctly. > NetBIOS Support Link/X.25 does not support NetBIOS emulation packets. NetBIOS is only suited to bridging and routing over high-speed network links such as those supported by Link/T1. With Link X.25, timeouts occur when transferring NetBIOS packets. > NetWare Care NetWare Care allows a network manager to view the network status for the local LAN. It does not view sessions across the Link/X.25 router. NetWare Care only recognizes the local router. At this writing, NetWare Care must be used only with NetWare 2.1x-based file servers. HARDWARE CONFIGURATION For the router PC hardware, we recommend you select from one of the tested machines listed in this booklet. A fast processor is needed for optimal performance and we recommend at least an AT-compatible 286-based machine. MEMORY Link/X.25 needs at least 512K RAM in the router PC. Link/X.25 will also work in extended memory, protected mode. > LAN Adapters The Link/X.25 router also requires a LAN adapter to connect the router to the network. A list of tested adapters for Link/X.25 is included in this document. NOTE: In a 386-based PC, some 'dumb' LAN adapters actually perform faster than 'smart' LAN adapters that have on-board processors and memory. > WAN Adapter You will also need a Novell X.25 Adapter for PC or a Novell X.25 Adapter for PS/2 to provide the connection to the X.25 communications line. WAN CONNECTION > Physical Connection A CSU/DSU or full duplex synchronous modem is required at each router location. We have listed only the modems tested and certified in our Novell laboratories. Note that if the CSU/DSU is equipped with a V.35 interface, an RS-232 to V.35 interface converter is also needed. PDN CERTIFICATION NetWare Link/X.25 has been tested or certified with the following PDNs. NORTH AMERICA Canada (Telecom) Datapac Canada (CN/CP) Infoswitch Mexico Telepac United States Accunet United States Infonet United States SpiritNet (Telenet) United States Tymnet United States CompuServe EUROPE Austria Radaus Data Belgium DCS Bahamas BATELCO Denmark Datapak Finland Datapak Finland Digipak France Transpac Germany Datex-P Italy ITAPAC Luxembourg Luxpak Netherlands Datanet-1 Norway Datapak Portugal Telepac Spain Iberpac Sweden Datapak Switzerland Telepac United Kingdom PSS EURASIA Australia Austpac Hong Kong Datapak Hong Kong Intelpak Japan (NTT) DDX-P Singapore Telepac RECOMMENDED HARDWARE ENVIRONMENTS Personal Computers LAN Adapters Modems Routers Router LAN Adapters Novell AT 286 (10 MHz) Novell NE/2 Ethernet (MCA) UDS 2425 Novell 386 (16 MHz) Novell NE1000 Ethernet UDS 224 AT/O Zenith 386 (20 MHz) Novell NE2000 Ethernet* IBM PS/2 55 SX (16 MHz) Novell RX-NET Arcnet IBM PS/2 80 (16 MHz) 3COM 3C505 Ethernet Compaq Deskpro 386/S (16 MHz) 3COM 3C523 Ethernet (MCA) Compaq 386/25 IBM Token-Ring 4** IBM Token-Ring 16/4** Standard Micro RX-NET * These are 16-bit adapter cards and are recommended for optimal NetWare Link/X.25 performance. ** Must use IBM LAN Support Program. ORDERING INFORMATION NetWare Link/X.25 883-000896-001 Novell X.25 Adapter for PC 905-301928-001 Novell X.25 Extended Adapter 905-302013-001 Novell X.25 Adapter for PS/2 905-301929-001