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Networking Basics

#networking #OSI #tcpip

Packets: header + payload

Sending an email example

  1. APPLICATION LAYER (in OSI application, presentation, session) will encapsulate the data from our email client

  2. application layer talks to transport layer through specific port (25 for SMTP)

  3. Data goes to Transport layer to be encapsulated into segments

Transport Layer

**TCP handshake:
– client sends a SYN segment to server requesting connection
– server sends the client a SYN-ACK segment to acknowledge the client's connection request
– client sense an ACK to server to acknowledge the server's connection request

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Network layer

**Coming from Transport layer:
– receives “segment” and encapsulates this segment in an IP packet
– attaches source host IP + destination host IP to the packet header
– sends to physical hardware layer

ARP: Address Resolution Protocol to find MAC address of IP

DHCP: Dynamic Host Configuration Protocol

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