Next Meeting: Sat, TBD
Meeting Directions

Be a Member


Help with Searching

20 Most Recent Documents
Search Archives
Index by date, title, author, category.


Mr. Know-It-All



Email Lists

SIGs (Internet, General Interest, Programming, Network, more..)

Online Chats


Past Presentations



Contact SCOUG

Copyright SCOUG

warp expowest
Pictures from Sept. 1999

The views expressed in articles on this site are those of their authors.

SCOUG was there!

Copyright 1998-2024, Southern California OS/2 User Group. ALL RIGHTS RESERVED.

SCOUG, Warp Expo West, and Warpfest are trademarks of the Southern California OS/2 User Group. OS/2, Workplace Shell, and IBM are registered trademarks of International Business Machines Corporation. All other trademarks remain the property of their respective owners.

The Southern California OS/2 User Group

September 2002

OS/2 Networking Essentials

a mishmash of basic networking information

by Steve Schiffman

Concepts to keep in mind

  • Described are elements of an independent network
  • Any connection to the outside world will be done via a gateway/router
  • This device will handle all those security type of things you all like to bring up
  • A full function router can be configured to provide a secure internal environment
  • A soho/home (low cost) gateway/router can do some of the above
  • Requester and Peer Services use NetBIOS API
  • Lan Server (WSeB) uses NetBIOS API
  • DB/2 uses NetBIOS API
  • TCP/IP is not NetBios API

Network Cable/Wiring

  • Cable Tester, if you do not have one, find someone who does
  • It can solve your home cabling problems before you spend hours trying to figure out why something is not working.
  • Cable Wiring Diagram

What is a network: The OSI (Open System Interconnect) Model

Composed of seven layers:

  • Layer 1 - Physical
  • Layer 2 - Data Link
  • Layer 3 - Network
  • Layer 4 - Transport
  • Layer 5 - Session
  • Layer 6 - Presentation
  • Layer 7 - Application

Layer 1 & 2 - Physical & Data Link

  • This is the underlying transport medium, i.e. wire, hubs, switches
  • Wiring types i.e. ethernet, Token Ring, frame relay, ppp, etc
  • Defines the electrical, mechanical, procedural and functions specifications for activating, maintaining and deactivating physical link(s) between systems. Provides reliable transit of data across the network. Defines physical addressing and topology.
  • The Media Access Control (MAC) portion of the Data Link layer manages protocol access to the physical network medium.

Layer 3 - Network

  • Routing and Routing management
  • Some protocols:
    IP, NetBEUI, IPX, ARP, RARP and there are many, many more
  • Many specifically for router to router communication

Layer 4 - Transport

  • Protocols - TCP, UDP, NetBEUI, SPX, etc.

Multi-Protocol Transport Services (MPTS)

Differentiating NetBIOS, NetBEUI, TCP/IP, NetBIOS over TCP/IP


  • NetBIOS is an Application Programming Interface, not a protocol
  • NetBIOS needs a network protocol such as NetBEUI or TCPBEUI to work
  • NetBEUI/NetBIOS for local segment LANs, non routable, but bridgeable
  • Computers using NetBIOS are known by their names, names must be unique on network
  • NetBIOS communication via standard format of Network Control Block (NCB)
  • NetBIOS provides three services: Name Service, Session Service, Datagram Service
  • NetBIOS Name Service:
    • Used to register/identify resources
    • Unique or Group
    • Names registered by node maintained in Name Table
    • NetBIOS name 15 bytes long, with a one byte suffix
    • Each node has a NetBIOS name consisting of the MAC address of that node
    • Each node also has a computer name
    • Note: do not use underscore character in a node name, it will not translate correctly when transported by TCPBEUI
    • Note: make the NetBIOS node name the same as the TCP/IP Host name
  • Note: RelishNet uses NetBIOS API


  • NetBEUI is the transport protocol for NetBIOS API
  • NetBEUI is broadcast-based
  • NetBEUI is non-routable
  • Designed for single segment LANs, is speedy, efficient and easy to use/configure
  • Computers and Network Resources on local network are discovered through broadcasts
  • Every node(computer) broadcasts its existence
  • Every node(computer) receives broadcasts and stores NetBIOS name and MAC address in RFCCACHE.LST table in memory (also writes out to file)


  • Hierarchical addressing scheme
  • IP is a routable protocol
  • TCP is a protocol that uses IP for its transport
  • Improperly set MTU (maximum transmission unit) values can adversely affect performance
  • Many other details not discussed in this presentation

NetBIOS (NetBEUI) over TCP/IP (called TCPBEUI on OS/2)

  • Implementation of NetBIOS to operate with TCP/IP as transport mechanism
  • Defined by RFCs 1001 and 1002
  • Solves the need to route a non-routable protocol
  • Encapsulates NetBEUI data in a TCP/IP or UDP/IP frame
  • Three modes of operation - Broadcast, Point-to-Point, and Mixed/Hybrid
  • Service: NetBIOS Name Server (NBNS)
  • Service: NetBIOS Datagram Distribution (NBDD)

  • Routing extensions:
    • The names file (RFCNAMES.LST), manually created
    • The Broadcast file (RFCBCST.LST), manually created
    • The Cache file (RFCCACHE.LST), internally generated

  • DNS with DDNS provides mapping services only if DOMAINSCOPE is configured
  • Needs to be used when Dynamic IP addresses are used
  • DOMAINSCOPE is configured in NetBios over TCP/IP protocol section of protocol.ini file (via MPTS GUI)

  • WINS is a Microsoft DNS server for NetBIOS names to IP address mapping
  • Microsoft's implementation of NetBEUI over TCP/IP is faulty, does not confirm to the RFC's, i.e. their WINS function only works for Microsoft operating systems

  • You use NetBios over TCP/IP when you need to have NetBIOS applications communicate with nodes that are on separate LAN segments (subnetworks)
  • Using TCPBEUI, you can use the full TCP/IP set of management tools, i.e. PING, TRACERTE, IPTRACE

What's new in MPTS V6 and TCP/IP V4.31

    • 8 physical adapters supported
    • 4 logical instances per physical adapter
  • MPTS GUI only handles 4 physical adapters, others must be added manually to PROTOCOL.INI file in \IBMCOM subdirectory
  • When defining protocols, you can define as many *non*-conflicting protocols as needed per logical instance

  • New Functions
    • Dynamic IP Enhancements
    • Java-based Configuration and Management
    • DHCP Relay Agent
    • Redundancy for a failed LAN Adapter
    • Implements Fault Recovery and Isolation for Host
    • PreBoot eXecution Environment (PXE) 2.1 Support
    • FTPD mode to transfer files through packet filter-based firewalls
    • RXFTP additional mode to support above

  • TCP/IP and TCPBEUI Enhancements
    • Sendmail
    • Use of DNS for NetBIOS name resolution
    • Dynamic update of Names List and Broadcast List

For the more nitty-gritty hands-on aspects of networking, take a look at materials from the presentation Mike Rakijas gave to SCOUG in April 2002 titled Networking Your Home.

The Southern California OS/2 User Group
P.O. Box 26904
Santa Ana, CA 92799-6904, USA

Copyright 2002 the Southern California OS/2 User Group. ALL RIGHTS RESERVED.

SCOUG, Warp Expo West, and Warpfest are trademarks of the Southern California OS/2 User Group. OS/2, Workplace Shell, and IBM are registered trademarks of International Business Machines Corporation. All other trademarks remain the property of their respective owners.