B3 Jan 2022 SD Network Basics OSI Layers
05-01-2022
OSI LAYERS: OSI - Open System Interconnect
7 layer model
Referance model
-dont use
we use - TCP/IP protocol suite
IPX SPX Noval Netware Apple Talk
-osi understand network
-osi - troubleshooting network
ISO - International Organization for Standardization
IEEE - Institute of electrical and electronics engineering
ieee 802
Layer 7 Application
Layer 6 Presentation -- 5,6,7 top layer software layers
Layer 5 Session
Layer 4 Transport --heart of OSI layer, end to end connectivity
Layer 3 Network
Layer 2 DataLink -- 1,2,3 hardware layer
Layer 1 Physical
Layer 3 Network - ROUTER
Layer 2 DataLink - SWITCH
Layer 1 Physical - HUB
Application Layer:
-user interface: web browser-chrome,firefox,edge (HTTP), filezilla (FTP),cuteFTP
putty, outlook,
-Server: server application-tomcat server, glashfish,iis,httpd, vsftp,ssh,mailserver(MS exchange, zimbra)
-understand user request by protocols
Protocols Port No
HTTP 80
HTTPS 443
FTP 20,21
SSH 22
TELNET 23
SMTP 25
POP3 110
IMAPv4 143
NTP 123
DHCP 67,68
DNS 53
RDP 3389
SNMP 161,162
LDAP 389
KERBEROS 88
Presentation layer:
-Text,pdf,doc,html,
mp3,3gp,wmv,mp4,flv --convert into ASCII format
gif,jpg,png,
ASCII - American standard Code for Information Interchange
-Encoding and Decoding
-Compress and Decompress
-Encrypt and Decrypt
Http - https
telnet - ssh
Session:
Establish the session
maintain, terminate the session
Tansport Layer:
-it provide end to end connectivity
-segmenting - chopping the data into small pieces - 64byte-1500bytes
-numbering and sequncing
-multiplex and demultiplex of protocols into TCP and UDP
TCP-Transmission control protocol UDP - User Datagram Protocol
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http,ftp,telnet,ssh,smtp,ntp tftp,dhcp,dns
acknowledgement based protocol no ack
reliable non reliable
connection oriented connection less
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-flow control
-windowing
PDU - Packet Data Unit
trasport - add header to PDU - TCP + PDU -- Segment
Segment - network layer
Network Layer:
-Routed protocols - IP address ,
-Routing protocols -rip,eigrp,ospf
-best path selection to reach destination
-logical addressing
network adds a header to PDU(Segment) - SIP DIP Segment -Packet
SIP+DIP -- NETWORK HEADER
packet sent to data link layer
Datalink Layer:
LLC - Logical link control
-Frame relay,hdlc,ppp,mpls-WAN protocols
MAC - Media Access Control
48bit 12Hex
-by manufacture of device NIC/ethernet card
Hearder - Smac+Dmac
Tail - CRC
Smac+Dmac packet CRC -- frame
CRC - Cyclic Redundancy Check
-check data for errors
-privents data correption
frame - physical layer
Physical Layer:
converts frame into bit stream
based on physical connectivity
optical fiber cable - lightwaves
utp/stp, coaxial -- electrical signal
wifi,wireless --- radio signal
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Application -http,ftp, -- responde
Presentation -ascii,compress,encrpt --decode,decompress,decrypt
Session -start session ---check
Transport -segment, numbering n sequence, ---segment no,assemble Transport
Network -sip,dip ---dip,sip-segment Network
DataLink -smac dmac crc ---smac/dmac-crc-packet DataLink
Physical -bit stream/signal ---bit stream -frame Physical
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OSI layer TCP/IP - DOD
Application
Presentation Application
Session
Transport Transport
Network Internet
DataLink Network Access
Physical
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