Table of Contents DOS
TCP/IP Tutorial and Technical Overview

4.15 NetBIOS Services Protocol

NetBIOS Services Protocol is a standard protocol. Its status is elective.

A relevant application protocol is described in RFCs 1001 and 1002. They describe the standard to implement the IBM NetBIOS services (as described in IBM Technical Reference PC Network) on top of the TCP and UDP protocol layers. Remember that many of today's IBM token-ring applications use the NetBIOS services to communicate over the IBM Token-Ring Network. Examples are the OS/2 LAN Server and the DOS LAN Requester. Among the OEM applications which use NetBIOS services is Lotus Notes.

All of today's NetBIOS applications run on PCs and PS/2s. Implementation of NetBIOS on TCP/IP would bring the power of mini and large computers to the PC user. A typical application would be to use large systems as file servers.

4.15.1 Implementations OS/2

This section gives an overview of the functions of the NetBIOS Kit of TCP/IP V2.0 for OS/2, also known as TCP/NetBIOS.

TCP/NetBIOS enables NetBIOS applications running on OS/2 workstations with IBM TCP/IP to communicate, over a TCP/IP network, with other OS/2 workstations with TCP/IP and TCP/NetBIOS, or other vendor platforms running equivalent RFC 1001 and RFC 1002 compliant TCP/IP support. TCP/NetBIOS does not communicate with native NetBIOS nodes, but users who presently have native NetBIOS networks can operate TCP/NetBIOS networks concurrently on the same local area network. The two NetBIOS networks will be independent and will not communicate with each other.

TCP/NetBIOS is compatible with both IBM's NetBIOS and Microsoft's NetBIOS specifications.

TCP/NetBIOS can be used with any adapter supported by TCP/IP V2.0 for OS/2. It replaces the NetBIOS support provided with the OS/2 Communications Manager. NetBIOS application programs remain unchanged, but will now communicate over TCP/IP instead of directly over a LAN. TCP/NetBIOS is a TCP/IP application but application programs that interface with TCP/NetBIOS for communications are not TCP/IP applications because they do not interface directly with TCP/IP.

Figure: TCP/IP and NetBIOS

Two levels of OS/2 interfaces exist for the NetBIOS. An application program can use a Dynamic Link Routine interface, or a Device Driver interface. An application program may use either type of OS/2 interface, but cannot use both interfaces at the same time if it wishes to be considered as a single application. Resources provided to and resources obtained from one of the OS/2 interfaces cannot be used at the other OS/2 interfaces. In order for an application program to use a Device Driver interface, the application program itself must be a device driver or have a device driver as one of its components. The application program device driver must be set up to support communication between device drivers. In doing this, the application program device driver can be called by the NetBIOS for the posting of events.

Figure: NetBIOS Kit of TCP/IP V2.0 for OS/2

NetBIOS provides four kinds of services:

  1. Name management services.

    It provides support for:

  2. Session services.

    A session is a connection-oriented service used for reliable data transfer. It has three phases:

  3. Datagram services.

    Connectionless services are available through the use of monocast, multicast and broadcast messages. They are used to support low-overhead communications with minimal error checking. NetBIOS datagrams are carried within UDP packets.

  4. Miscellaneous services.

    They are used to handle unusual situations such as errors.

Both session and datagram services use the logical network names to address recipients.

The RFCs define three modes of operations:

  1. Broadcast or B-node:

    This mode uses broadcast to identify the target node and then establish point-to-point communications between B-nodes. This is the most commonly implemented mode. This covers TCP/IP implemented in environments which support broadcast, particularly Ethernet.

  2. Point-to-Point or P-node:

    This mode requires the use of a NetBIOS Name Server and a NetBIOS Datagram Distribution Server. These servers are complex and difficult to implement. P-nodes operate in an environment where there are no broadcasts, only point-to-point connections.

  3. Mixed mode or M-node:

    M-nodes are the same as P-nodes but with the ability to perform broadcasts.

TCP/NetBIOS supports the B-node class of implementation with some P-node extensions.

The RFCs cover naming conventions:

TCP/NetBIOS provides the basic NetBIOS services required for B-nodes and provides some P-node extensions. This allows TCP/NetBIOS to operate through routers and to use TCP/IP domain name servers. The extensions do not alter the protocol as seen by a B-node. The extensions are implemented by two additional files (the BROADCAST file and the NAME file) and the use of the Domain Scope String.

OS/2 LAN Server V4.0

An alternative implementation of RFCs 1001 and 1002 is provided in the TCPBEUI component of OS/2 LAN Server V4.0. TCP/IP communications is basically provided in the MPTS support included in LAN Server. This, together with TCPBEUI, provides an implementation of RFC 1001/1002 which is similar to that described earlier for TCP/IP V2.0 for OS/2. Both LAN Server and LAN Requester are able to use this support. Performance is generally better using TCPBEUI than it is using the TCP/NetBIOS support described earlier. DOS

TCP/IP V2.1.1 for DOS offers, as a separately orderable kit, an implementation of TCP/NetBIOS which is similar in terms of function to the OS/2 implementation described in the previous section. AIX/6000

NetBIOS and IPX support for AIX is provided by the product AIX NetBIOS and IPX Support/6000. The product includes industry standard communications protocol support for NetBIOS (NetBEUI), IPX/SPX and RFC 1001/1002. With this you have additional network application programming interfaces to allow you seamless access to existing systems.

Table of Contents Line Printer Daemon