Transcript Network Protocols

BTEC IT Unit 05 - Lesson 05
Network Protocols
Mr C Johnston
ICT Teacher
www.computechedu.co.uk
Session Objectives
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Understand the meaning and use of common protocol suites
used when networking computers including: SNMPv3, ICMP,
HTTP, FTP, TFTP, NTP
What Is A Protocol?
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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
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You need to know about the following protocols:
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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 for
PowerConnect Switch
Switch status animation
SNMP Options
Overview of Protocols2
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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 website URL to
Pingingconnection
a server
check internet
which is working
is functional.
OK
Pinging a client
which is turned off
Using ICMP – TraceRT
(trace route)
TraceRT from client
to server – only
TraceRT
from
clientwith
takes
1 step
to client
whichresponse
is
average
switched
off – tries
of 1ms
30 times to contact
with each request
from client
failing.TraceRT
* = failed
to router – only
contact.
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 my house to www.google.co.uk – each data
packet goes through 13 different routers before the website is
found.
Overview of Protocols2
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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.
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Applied A2 Book – p39