Thursday, December 25, 2008


Protocols are rules and procedures for communication.

 How Protocols Work
The Sending Computer
Breaks data into packets.
Adds addressing information to the packet
Prepares the data for transmission.

The Receiving Computer (same steps in reverse)
Takes the packet off the cable.
Strips the data from the packet.
Copies the data to a buffer for reassembly.
Passes the reassembled data to the application.

Protocol Stacks (or Suites)
A combination of protocols, each layer performing a function of the communication process.
Ensure that data is prepared, transferred, received and acted upon.

The Binding Process
Allows more than one protocol to function on a single network adapter card. (e.g. both TCP/IP and IPX/SPX can be bound to the came card
Binding order dictates which protocol the operating systems uses first.
binding also happens with the Operating System architecture: for example, TCP/IP may be bound to the NetBIOS session layer above and network card driver below it. The NIC device driver is in turn bound to the NIC.

Standard Stacks
IBM SNA (Systems Network Architecture)
Digital DECnet
Novell NetWare
Apple AppleTalk

Protocol types map roughly to the OSI Model into three layers:
Level Service Users 
Application Layer  Presentation Layer  Session Layer

Transport Services 
Transport Layer

Network Services 
Network Layer  Data Link Layer  Physical Layer

Application Protocols
Work at the upper layer of the OSI model and provide application to application interaction and data exchange. 

APPC-IBM's peer to peer SNA protocol used on AS400's
FTAM: an OSI file access protocol.
X.400: international e-mail transmissions.
X.500: file and directory services across systems.
SMTP: Internet e-mail.
FTP: Internet file transfer
SNMP: Internet network management protocol.
Telnet: Internet protocol for logging on to remote hosts.
Microsoft SMB: client shells and redirectors.
NCP: Novell client shells or redirectors.
AppleTalk and AppleShare: Apple's protocol suite.
AFP: Apple's protocol for remote file access.
DAP (data access protocol): DECnet file access protocol.

Transport Protocols
These protocols provide communication sessions between computers and ensure data is moved reliably between computers. 

TCP (transmission control protocol): internet protocol for guaranteed delivery of sequenced data.
SPX (sequenced packet exchange): Novell protocol suite.
NWLink: Microsoft implementation of IPX/SPX.
NetBEUI: establishes communications sessions between computers and provides the underlying data transport services.
ATP, NBP: Apple's communication session and transport protocols.

Network Protocols
These provide link services 
They also 
o addressing and routing,
o error checking and
o retransmission requests.
Define rules for Ethernet or Token Ring.

IP (Internet Protocol): packet forwarding and routing.
IPX: (Internetwork Packet Exchange): Novell's protocol for packet forwarding and routing.
NWLink: Microsoft implementation of IPX/SPX.
NetBEUI: Transport for NetBIOS sessions and applications.
DDP (datagram delivery protocol): An AppleTalk data transport protocol.

blogger templates | Make Money Online