OS/2 Networking Essentials

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.

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.