Materials About CCNA
OSI
(ISO) International organization for standardization
Iso has designed a reference model called osi reference model(open system interconnection).
It has 7 layers. It says thatAny n/w for comunication needs 7 layers
7.Application layer:
The user uses application layer to send the data. The protocols@ this layer are ftp,http,smtp(e-mail) telenet etc.
6.Presentation layer:
Presentation layer takes the data from application layer and presentIn different formats for securing reason. The services offered @This layer areCompression – decompressionCoding – decodingEncryption - decryption
5. Session layer:
Establishing the session or the conectivity n/w n/w 1 & n/w 2 is doneBy the session layer.It 1. Establishes a session2. maintains it &3. Terminates it b/w the application
4. Transport layer:
End-end connectivity during a session b/w two application is doneBy the transport layer. It also decides the type of connection like tcpor udp i.e. connection oriented or connection less.Services:SequencingFlow ctrl, error detection & correctionTransport layer info + data is called segment
3. Netwrok layer :
Logical addressing is done at thenetwork layer i.e. source address &destination address are attached to the data.Protocols @network layerRouted protocols routing protocolsEg: ip,ipx eg: rip,igrp,ospfRouted protocols: they always carry the data along with themRouting protocol: they identify the path for routed protocol tocarry the dataAt this layer routers & layer 3 switches forms packets.
2.Data link layer:
It has two Sub layersa)MAC{Media access control } b) LLC {logical link control framing of data}Ip address is lik the pincode & MAC address is like house number.Here layer2 switches are used.Wab protocols used at this layer are PPP,HDLC,FP,X.25 etc.Here error checking CRC bits are added to the packetsDLL info+ packets --> frames
1. physical layer:
Takes care of physical connectivity i.e connector,cable etc. hereFrames are converted to bits (1’s & 0’s).The devices like hubs, repeaters,cables & connectors are used atthis layer
(ISO) International organization for standardization
Iso has designed a reference model called osi reference model(open system interconnection).
It has 7 layers. It says thatAny n/w for comunication needs 7 layers
7.Application layer:
The user uses application layer to send the data. The protocols@ this layer are ftp,http,smtp(e-mail) telenet etc.
6.Presentation layer:
Presentation layer takes the data from application layer and presentIn different formats for securing reason. The services offered @This layer areCompression – decompressionCoding – decodingEncryption - decryption
5. Session layer:
Establishing the session or the conectivity n/w n/w 1 & n/w 2 is doneBy the session layer.It 1. Establishes a session2. maintains it &3. Terminates it b/w the application
4. Transport layer:
End-end connectivity during a session b/w two application is doneBy the transport layer. It also decides the type of connection like tcpor udp i.e. connection oriented or connection less.Services:SequencingFlow ctrl, error detection & correctionTransport layer info + data is called segment
3. Netwrok layer :
Logical addressing is done at thenetwork layer i.e. source address &destination address are attached to the data.Protocols @network layerRouted protocols routing protocolsEg: ip,ipx eg: rip,igrp,ospfRouted protocols: they always carry the data along with themRouting protocol: they identify the path for routed protocol tocarry the dataAt this layer routers & layer 3 switches forms packets.
2.Data link layer:
It has two Sub layersa)MAC{Media access control } b) LLC {logical link control framing of data}Ip address is lik the pincode & MAC address is like house number.Here layer2 switches are used.Wab protocols used at this layer are PPP,HDLC,FP,X.25 etc.Here error checking CRC bits are added to the packetsDLL info+ packets --> frames
1. physical layer:
Takes care of physical connectivity i.e connector,cable etc. hereFrames are converted to bits (1’s & 0’s).The devices like hubs, repeaters,cables & connectors are used atthis layer
posted by Arivu at
3:09 PM
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