NetworkingNetworking

Network Classification, by there:

3 The Rules they use to exchange data:

Protocols

ProtocolsProtocols

Communication protocols are agreed sets of rules and procedures for computers to exchange information.

Like humans agreeing to speak the same language during a conversation.

For two computers to exchange data, they must be using the same protocols.

ProtocolsProtocolsThere is a protocol for each network communication task, such as:

- how to send data over the Internet (TCP/IP)

- how to send and receive email (POP, IMAP)

- how to request and deliver web pages (HTTP)

-how to request and deliver files (FTP)

-Other common protocols: Appletakl, IPX/SPX, Netbui, All LAN protocols

ProtocolsProtocols

Sometimes there is more than one choice of protocol for a task, such as how messages pass across a network (IPX/SPX vs TCP/IP).

As long as all the connected computers use the same protocol, it really does not matter which protocol is used.

The internet only works because TCP/IP, POP, FTP and HTTP are universal standards.

Protocols - Protocols - EthernetEthernet• Ethernet is a network standard allowing PCs to

communicate in networks• Ethernet is based on bus and star networks &

is inexpensive and easy to install and maintain• Ethernet uses cable to transmit data• Ethernet transfer rates:• originally 10 Mbps• Fast ethernet, 100 Mbps using twisted

pair (Cat 5)• Gigabit ethernet 1000 Mbps

Protocols – Token RingProtocols – Token Ring

• Token ring, a LAN technology• Requires network devices share or pass a

special signal called a token• One token per network so only one computer

can transmit data at a time• Token ring is based on a ring topology

Protocols – TCP/IPProtocols – TCP/IPThe universal protocol for internet communications. The backbone of the internet.

Is actually two complementary protocols…

TCP (Transport Communication Protocol) and

IP (Internet Protocol)

Internet Internet AddressingAddressing

Humans like working with names (e.g. www.microsoft.com) but computers use numbers (e.g. 10.77.91.19).

That is an IP address – four ‘octets’ separated by dots, each octet can be between 0 and 255.

All internet communications use IP addresses, not URLs.

AddressingAddressingWhen you enter a URL your ISP looks up the URL in its DNS to see if it has the corresponding IP address.

If it does have it, the server is located by IP address and the communication begins.

If the IP address is not in your ISP’s DNS, the DNS asks another, bigger DNS.

If that DNS does not have it, a “grand master” DNS server will be asked.

If that fails, you get an error message saying the domain does not exist.

AddressingAddressingThe domain name server database stores the names and IP addresses of every internet domain on the planet.

The database is distributed across thousands of computers across the planet but it acts as a single, massive database – it’s the biggest distributed database in the world.

Addressing - URLsAddressing - URLs

URL (Uniform Resource Locators) are made up of segments e.g. http://www.wedderburn-college.vic.edu.au

http:// specifies the protocol for the request.

www refers to the world wide web – made up of webservers, webpages and browsers.

Wedderburn-college.vic.edu.au is the domain name.

Other network ProtocolsOther network Protocols

• Apple File Protocol, (AFP)• Microsoft NetBios Extended User Interface

(NetBEUI)• 802.11, wireless standards• Wireless communications 50mtrs to 300 mtrs• Hot spot, location where users can connect

mobile computers to a wireless network• WAP, wireless application protocol; allowing

wireless mobile devices to access internet & its services

• Uses a client/server network; wireless device contains client software

• WAP enabled devices, devices that support WAP, eg. web-enabled phones, etc.