Today's Topics

• Computer Networking
• NetBios Programming
• Advanced Networks

Computer Networks

• Local-Area and Wide-Area Networks (LANs/WANs)
  Ethernet: 10/100 Mbps (Local-Area)
  • Packets broadcast on shared media (the 'Ether')
  • Coax (10Base2): Terminators prevent signal reflection
  • Twisted Pair (10BaseT): Hubs retransmit packets to links
  • No Quality of Service (QoS) Guarentees

• Data Delivery
  • Broadcast: One-to-all
  • Multicast: One-to-many (using group name)
  • Unicast: One-to-one (each host has unique name)

• Data Transport Protocols
  • Datagram
    • Packets may be lost
    • Packets may be reordered (except ATM)
    • Can Broadcast, Multicast, Unicast
    • Example: UDP
  • Connection-Oriented
    • Reliable connection between endpoints
    • Lost packets are retransmitted
    • Limited to point-to-point (Unicast) links
    • Example: TCP

• Programming Models
  • Client/Server (typical case)
    • Server is a centralized, permanent resource
    • Clients are short-lived, stateless programs
    • Unicast Connections between server and client
  • Peer Model
    • All Programs share information
    • Multicast or broadcast data between hosts

• Network Adapter & Software
  • Hardware address filters
  • Interrupt On Incoming Packet
  • Demultiplex incoming packet
  • Deliver data to appropriate application

NetBIOS

• Local Area Network service
  • Independent of underlying hardware
    • Ethernet
    • Token Ring
    • FDDI
  • Independent of underlying Protocols
    • Standalone packets
    • Encapsulation in IP
  • Designed for Local Area Network
    • Assumes single local network segment
  • Implementation
    • DOS Packet Driver
    • Serice provided by WinNT, Win95, WFWG

• NetBIOS Provides
  • Naming Service
    • Provides Unique names on Network
    • Global Namespace

  • Multiple types of communication
    • Datagram Broadcast
    • Datagram Multicast
    • Datagram Unicast
    • Reliable Connection

• Communication with NetBIOS
  • Interrupt 5C

• Network Control Block (NCB)
  • Basic NetBIOS Data Structure
  • Command Field: Determines what action to take
  • Inputs/Outputs/Pointers: All passed through NCB

• NetBIOS Response Methods
  • Blocking Functions: Wait until even occurs
  • CallBack Functions: Register function to call when event occurs
    Operates just like an interrupt

• NetBIOS Names
  • 16-character NetBIOS identifiers
  • Local Names: Unique across the LAN (enforced by NetBIOS)
  • Group Name: Shared among multiple machines (Multicast)

• Examples
  • Broadcast/Multicast Datagrams
    • Sender & Receiver ADD NAME
    • Loop while running
      • Sender SENDS Broadcast Datagram
      • Receiver RECEIVES Datagram
    • Sender & Receiver REMOVE NAME

  • Unicast Connection
    • Sender & Receiver ADD NAME
    • Receiver LISTENS
    • Sender CALLS (Connection Established)
    • Loop while running
      • Sender SENDS
      • Receiver RECEIVES
    • Sender or Receiver HANGUP (Connection Terminated)
    • Sender & Receiver REMOVE NAME

• Complete Documentation: CBIS NetBios Programmers Reference

• Programming with NetBIOS in the ECE291 Lab
  • Lockwood's NetLIB: (API to make your life easy!)
    • NetLIB readme file
    • NetLIB: ASM source code & examples

  • Important Variables
    • grp_name: Multicast Group name (Default=ECE291NetLib$$$$)
    • my_name: My unique network id (Default=ECE291Player0$$$)
    • TXBUffer: Transmission buffer
      Load with data that you want to transmit then call SendPacket.
    • RXBUffer: Receive Buffer
      Filled with data from incoming network packet network just before your netpost function is called.

  • Procedures
    • NetINIT: Call at start of your program

    • netpost: Callback function called whenever a datagram arrives.
      
      • Called with
        • BX = pointer to receive buffer
        • AX = length of data
      • Because this routine is called from an interrupt, it must:
        • Preserve all registers
        • Avoid DOS and LIB291 calls

    • SendPacket: Call with AX = Length of TXBuffer to transmit data

    • NetRelease: Call at the end of your program

Advanced Networks

• ATM: Asynchronous Transfer Mode (Local & Wide-Area)
  • Data transmitted as 53-byte cells
  • Messages transmitted using Adapatation Layer (AAL)
  • Transmits data at rate of 155 Mbps (OC3), 622 Mbps (OC12), 2.4 Gbps (OC48), or 10 Gbps (OC192) per host and shared on virtual circuits.
  • Preserves Quality of Service, allowing integrated data (voice, video, IP) to carried over common network.
  • See the iPOINT Testbed for information about ATM research on this campus.

Return to ECE291 Lecture Index