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Copyright 2017, 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
P.O. Box 26904
Santa Ana, CA 92799-6904, USA

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

  • 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

  • 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)

TCP/IP

  • 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

  • TCPBEUI
    • 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.