Introduction to Network

1
Introduction to Network

• By atomer20/07/2004

2
Outline

• Introductory
• Physical Layer
• Link Layer
• Network Layer
• Transport Layer
• Application Layer
• Network Devices
• Network Services

3
Introductory

• ISO/OSI network model
• International Standard Organizations Open System
  Interconnect model
• TCP/IP network model
• It is a 5-layer network model, and become
  popular in todays implementation.
• http//www.uwsg.iu.edu/usail/network/nfs/network_l
  ayers.html

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Physical Layer

• Ethernet
• First widely deployed high-speed LAN in 1970s
  mid.
• Token ring, FDDI, and ATM are more complex and
  expensive than Ethernet.
• Switch to another LAN technology was usually the
  higher data rate of the new technology in
  19701990.
• The low cost is also due to the fact that
  Ethernets multiple access protocol, CSMA/CD, is
  completely decentralized, which has also
  contributed to a simple design.
• Invented by Bob Metcalfe in early 1970s when he
  occupied in Xerox Palo Alto Research Center.
  (along with colleague David Boggs) In 1979, Bob
  Metcalfe formed his own company, 3Com.

5
Link layer

• MAC address
• A LAN address is also variously called a physical
  address, an Ethernet address, or a MAC (Media
  Access Control) address. The LAN address is 6
  bytes long, giving 248 possible LAN address.
• IEEE manages the physical address space. IEEE
  allocates the chunk of 224 addresses by fixing
  the first 24 bits of a physical address and
  letting the company create unique combinations of
  the last 24 bits for each adapter.

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Network Layer

• IPInternet Protocol
• Computers in TCP/IP-based Internet is addressed
  by a specific address IP. IP address is
  composed of 32-bits.
• Sub-network
• Network mask

7
Transport Layer

• TCPTransmission Control Protocol
• Be used to transfer data in reliability way.
• UDPUser Datagram Protocol
• A simple data transfer method.

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Application Layer

• Refer to those applications which we use, or
  those applications exchange data via TCP/IP
  environment.

9
Network Devices

• Repeater
• Hub
• Switch
• Bridge
• Router
• (Firewall)
• (NAT)

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Network Services

• The Internet Engineering Task Force (IETF) is a
  large open international community of network
  designers, operators, vendors, and researchers
  concerned with the evolution of the Internet
  architecture and the smooth operation of the
  Internet. It is open to any interested
  individual.
• http//www.ietf.org/

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• ARPAddress Resolution Protocol
• A protocol be used to translate between LAN
  address and IP address.

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• DHCPDynamic Host Configuration Protocol
• An extension of the BOOTP protocol, be used to
  allocate a dynamic IP address for a requested
  host.
• ICMPInternet Control Message Protocol
• ICMP is used by hosts, routers, and gateways to
  communicate network layer information to each
  other.

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• DNSDomain Name Service
• Translation between IP and domain name
• forward domain name to IP address
• backward IP address to domain name
• RFC1034 and RFC1035 illustrate the detail of DNS
• BINDBerkeley Internet Name Domain

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• HTTPHyper Text Transfer Protocol
• Developed by CERN, in recently its a famous
  information-exchange technology.
• There are two kinds of presentation on HTTP. one
  is static and the other is dynamic.
• Static pages is a common and simple way for
  presentation.
• Dynamic presentation usually be combined with
  databases.

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• FTPFile Transfer Protocol
• A simple protocol be used to transfer files.
• Transfer mode
• PORT
• PASSIVE
• Reference
• RFC 959
• RFC 2228 security extension
• RFC 2640 internationalization

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• SMTPSimple Mail Transfer Protocol
• POPPost Office Protocol
• IMAP--Internet Message Access Protocol
• Reference
• RFC 821 SMTP
• RFC 1939 POP3
• RFC 3501 IMAP

17

• Telnet
• A simple communication protocol be used to
  transfer text data on network.
• By the way, BBS is Bulletin Board System and it
  isnt a PROTOCOL!!!
• telnet might be a good tools for testing your
  online server.
• Reference
• RFC 854
• RFC 855

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• SSH Protocol
• SSH encrypts all traffic (including passwords) to
  effectively eliminate eavesdropping, connection
  hijacking, and other network-level attacks.
• SSH is based on SSLSecure Sockets Layer
• More information
• http//www.openssl.org/
• http//www.openssh.com/

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• NNTP--Network News Transfer Protocol
• NNTP specifies a protocol for the distribution,
  inquiry, retrieval, and posting of news articles
  using a reliable stream-based transmission of
  news among the ARPA-Internet community.
• Reference
• RFC 977

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• NFSNetwork File System
• The Network File System (NFS) version 4 is a
  distributed file system protocol which owes
  heritage to NFS protocol version 2, RFC 1094, and
  version 3, RFC 1813. Unlike earlier versions, the
  NFS version 4 protocol supports traditional file
  access while integrating support for file locking
  and the mount protocol. In addition, support for
  strong security (and its negotiation), compound
  operations, client caching, and
  internationalization have been added. Of course,
  attention has been applied to making NFS version
  4 operate well in an Internet environment.
• Reference
• RFC 3530 v.4