mr c johnston ict teacher btec it unit 05 - lesson 05 network protocols

Mr C JohnstonICT Teacher

www.computechedu.co.uk

BTEC IT Unit 05 - Lesson 05

Network Protocols

Session Objectives

Understand the meaning and use of common protocol suites used when networking computers including: SNMPv3, ICMP, HTTP, FTP, TFTP, NTP

What Is A Protocol? A protocol is a set of rules governing how computers

communicate together and exchange data, A example of a protocol in real life is the rules of English

– a sentence must start with a capital letter and end with a punctuation mark,

In networking a protocol defines: how data should be sent, how its received and how computers acknowledge receipt of data,

To use a protocol software will need to be installed – these often come as part of your OS or NIC driver,

All computers within a network must use the same protocol in order for communication to take place.

Overview of Protocols1

You need to know about the following protocols: SNMPv3 – Simple Network Management Protocol version 3 - is

a protocol which is widely used in networks to control devices such as routers, switches, networked printers etc. It monitors the devices for adverse conditions and that require attention. SNMP works by server-based ‘manager’ processes polling ‘agents’ (SNMP processes running on devices) to find out how well they are performing. The ‘manager’ process then reports these statistics to the network manager. Some ‘manager’ processes can then make changes to device performance via its ‘agent’. In addition, each ‘agent’ is able to generate an alert (called a ‘trap’) when something unexpected occurs that requires immediate attention. V3 of the protocol has better security than previous versions. SNMP is the technology behind a lot of network operator consoles showing the status of the device on-screen so they can be reconfigured.

Dell Management Console forPowerConnect Switch

Switch status animation

SNMP Options

Overview of Protocols2

ICMP – Internet Control Message Protocol - used within TCP/IP networks to diagnose problems during data transmissions e.g. not being able to find a server or device. One of the most common manual uses of ICMP messages is ‘ping’, which uses echo request to test connectivity between two IP devices by forwarding and acknowledging receipt of a chunk of data (and the timetaken for the transmission to take place). Some network utilities such as the traceroute command are based on ICMP.

Using ICMP - Ping

Pinging a server which is working OK

Pinging a client which is turned off

Pinging a website URL to check internet connection is functional.

Using ICMP – TraceRT (trace route)

TraceRT from client to server – only takes 1 step with average response of 1ms

TraceRT from client to router – only takes 1 step with average response of 3.7ms

Each of the 3 columns are a response from that router, and how long it took (each hop (step) is tested 3 times). For example, in the second routeTR, the first try took 3ms (3 milliseconds), the second took 2ms, and the third took 6ms.

TraceRT from client to client which is switched off – tries 30 times to contact with each request failing. * = failed contact.

TraceRT from my house to www.google.co.uk – each data packet goes through 13 different routers before the website is found.

Overview of Protocols2

TCP/IP – Transmission Control / Internet Protocol - protocol which is capable of allowing data to be routed so suitable for both LANs and WANs (can send data for same destination through different routes so very useful. Works with different LAN technologies and is not OS dependant and because of this was chosen as the protocol used on the internet in 1983. TCP deals with how data will be spilt / sent (data transmission protocol), IP adds addressing (addressing protocol)

FTP – File Transfer Protocol - a standard for moving files between computers on a WAN. Software used to transfer files between machines and allows files to be moved between different operating systems,

HTTP – Hypertext Transfer Protocol - defines how a web page is requested (such as by hyperlink), how it is found and how it is displayed. Secure HTTP (HTTPS) is an extension to the HTTP protocol that allows encryption and authentication for extra security of transactions over the Internet,

NTP – Network Time Protocol – used to synchronising the internal clocks of computer systems over a typical packet-switched network. This would, for example, enable all servers and workstations on a LAN to have the same time.

Applied A2 Book – p39