Identify the roles of different layers in the TCP/IP reference model?

Question

can any one give full answer

Answer 1

Application
User Interface
used for applications specifically written to run over the network
allows access to network services that support applications;
directly represents the services that directly support user applications
handles network access, flow control and error recovery
Example apps are file transfer,e-mail, NetBIOS-based applications
DNS; FTP; TFTP; BOOTP; SNMP;RLOGIN; SMTP; MIME; NFS; FINGER; TELNET; NCP; APPC; AFP; SMB Gateway

Presentation
Translation
Translates from application to network format and vice-versa
all different formats from all sources are made into a common uniform format that the rest of the OSI model can understand
responsible for protocol conversion, character conversion,data encryption / decryption, expanding graphics commands, data compression
sets standards for different systems to provide seamless communication from multiple protocol stacks
not always implemented in a network protocol
Gateway
Redirector

Session
"syncs and sessions"
establishes, maintains and ends sessions across the network
responsible for name recognition (identification) so only the designated parties can participate in the session
provides synchronization services by planning check points in the data stream => if session fails, only data after the most recent checkpoint need be transmitted
manages who can transmit data at a certain time and for how long
Examples are interactive login and file transfer connections, the session would connect and re-connect if there was an interruption; recognize names in sessions and register names in history
NetBIOS
Names Pipes

Mail Slots

RPC
Gateway

Transport

packets; flow control & error-handling
additional connection below the session layer
manages the flow control of data between parties across the network
divides streams of data into chunks or packets; the transport layer of the receiving computer reassembles the message from packets
"train" is a good analogy => the data is divided into identical units
provides error-checking to guarantee error-free data delivery, with on losses or duplications
provides acknowledgment of successful transmissions; requests retransmission if some packets don’t arrive error-free
provides flow control and error-handling
TCP, ARP, RARP;
SPX

NWLink

NetBIOS / NetBEUI

ATP
Gateway
Advanced Cable Tester

Brouter

Network

addressing; routing
translates logical network address and names to their physical address (e.g. computername ==> MAC address)
responsible for
addressing
determining routes for sending
managing network problems such as packet switching, data congestion and routing
if router can’t send data frame as large as the source computer sends, the network layer compensates by breaking the data into smaller units. At the receiving end, the network layer reassembles the data
think of this layer stamping the addresses on each train car
IP; ARP; RARP, ICMP; RIP; OSFP;
IGMP;

IPX

NWLink

NetBEUI

OSI

DDP

DECnet
Brouter
Router

Frame Relay Device

ATM Switch

Advanced Cable

Data Link

data frames to bits
turns packets into raw bits 100101 and at the receiving end turns bits into packets.
handles data frames between the Network and Physical layers
the receiving end packages raw data from the Physical layer into data frames for delivery to the Network layer
responsible for error-free transfer of frames to other computer via the Physical Layer
this layer defines the methods used to transmit and receive data on the network. It consists of the wiring, the devices use to connect the NIC to the wiring, the signaling involved to transmit / receive data and the ability to detect signaling errors on the network media
Logical Link Control
error correction and flow control
manages link control and defines SAPs
802.1 OSI Model

802.2 Logical Link Control
Bridge
Switch

ISDN Router

Intelligent Hub

NIC

Advanced Cable Tester

Media Access Control
communicates with the adapter card
controls the type of media being used:
802.3 CSMA/CD (Ethernet)

802.4 Token Bus (ARCnet)

802.5 Token Ring

802.12 Demand Priority

Physical

hardware; raw bit stream
transmits raw bit stream over physical cable
defines cables, cards, and physical aspects
defines NIC attachments to hardware, how cable is attached to NIC
defines techniques to transfer bit stream to cable
IEEE 802
IEEE 802.2

ISO 2110

ISDN
Repeater
Multiplexer

Hubs

Passive
Active
TDR

Oscilloscope

Amplifier

Answer 2

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