Modem Pooling in a NetWire Environment Making a Choice February 26, 1991 It is feasible to provide modem access to and from a NetWare LAN through a single point. Many organizations find this cost effective because it avoids providing a modem and phone line at every workstation which might have a reason to use a modem. A number of companies manufacture products which provide this ability. Novell produces, sells, and provides technical support for two; Access Server and NACS. For Calling into A NetWare LAN NetWare Access Server ------------------------------- NetWare Access Server software enables up to 15 remote users to dial in to a NetWare LAN and access all the services and files available on the network including applications, electronic mail and access to mainframes and minicomputers. The software turns a DEDICATED 80386 (or 486) Industry Standard Architecture (ISA) bus machine into a remote communications server by dividing the 386 (or 486) CPU into as many 640KB machines as installed RAM allows (up to 16). Each remote user calling in receives one or more of the virtual sessions in which to their work. A 16th session is reserved for network supervisors, allowing them to manage the network and remote connections and communicate with remote users. Remote users can dial into an Access Server through asynchronous modems or multiplexers using any PC or Macintosh, or most ASCII terminals. "ONLAN/PC" and "ONLAN/Mac" are provided with the Access Server and provide a particularly smooth interface with Access Server. However, many terminal emulation programs may be used a substitute for ONLAN/ONLANMAC with some limitations. "ONFILE" is also included with the Access Server software and is the only supported method of file transfer. Each owner of an Access Server is authorized to provide unlimited copies of ONLAN/PC and ONLANMAC to any site which may call the Access Server. Because all processing is handled by Access Server, only screen updates and keystrokes travel over the asynchronous lines and file access occurs at LAN speeds. Besides normal NetWare security there are number of specific Access Server security features which optionally may be used including: - Dial Back" which does not allow a caller to have a session until they have been called back at a telephone number specified by the network supervisor. Access Server allows the use of expanded memory above the 640 base for each individual session. For more information about Access Server see ACERUL.TXT in NOVA Library 9 (Communications). ACERUL.TXT is the "Rules of Thumb" for Access Server and it is important that you read it before making any decisions regarding hardware (including modems) and software to use with Access Server. For Calling Into or Out of a NetWare LAN NACS --------------------------------------------- The NetWare Asychronous Communications Server (NACS) turns a DEDICATED IBM PC/IBM PC AT or compatible into an asychronous communications server that allows up to 16 network stations to simultaneously call out of a LAN or to be accessed by a call into the LAN. Unlike Access Server, applications are not processed within the NACS but calls simply go through the WNIM+ ports on the NACS instead of the PCs COMM port. Users only have to specify a port by name in order to connect to a particular modem or line. In addition, NACS is capable of "rotating" if a port is busy. The recommended hardware for a NACS is: - An IBM AT or close compatible (but an XT or compatible will work) with: - A CGA OR MONOCHROME Video Adapter (Has no effect on caller's displays) - Not more 512K RAM (will run but not configure with 256K) - 10 MHz or more - In addition the following is REQUIRED: - One WNIM or WNIM+ card for each 4 simultaneous connections. - "NASI Compatible" communications software. (A list is provided in NACCOM.TXT in NOVA Library 9. - One asynchronous modem for each port to be used. (A NACS can also be connected directly to the asychronous ports on a Mini or Mainframe computer.) - The NACS machine may not have a microchannel bus. The Decision ------------ NOTE: There is no practical special limit on the number of Access Servers and NACS that can coexist on the same LAN. 1. For the best support for incoming calls Access Server is recommended. 2. For the best support for outgoing calls NACS is recommended. 3. For a LAN with a large amount of outgoing calls and a small amount of incoming calls NACS is recommended. However, each incoming call will a require a separate workstation in "call waiting status". With appropriate "NASI Compatible" software. 4. For a LAN with a large amount of outgoing calls AND a large amount of incoming we recommend that both an Access Server and a NACS be secured. 5. If there will only be 1 or 2 simultaneous incoming or outgoing calls at one time and you do not require the special feature of Access Server or NACS you may wish to explore third party products. Limitations ----------- 1. The large amount of data required to be transmitted across the phone lines for intensive graphics makes asynchronous remote use less than completely practical for such applications. 2. Mice and similar tracking devices do not lend themselves to use across asychronous lines. 3. Windows will not run in an Access Server.