4. Network Layer

Network Layer

• Addressing

  • IPv4

    • IP address depletion

    • Internet routing table expansion

    • Lack of end-to-end connectivity

  • IPv6

    • Increased address space

    • Improved packet handling

    • Eliminates NAT

    • Integrated security

  • IP characteristics

    • Connectionless

    • Best Effort

    • Media Independent

• Routing

  • Directly-connected routes

  • Remote routes

  • Default route

• Default gateway

  • routes traffic from the local network to remote networks

• ICMPv4

  • ping

    • test connectivity

    • echo request, echo reply

  • Pinging the local loopback

  • Pinging the default gateway

  • Pinging the remote host

  • traceroute

Transport Layer

• End to End Connection

  • Port Number

    • Source Port

    • Destination Port

• Segmentation

• Reassembling

• Transmission Control Protocol (TCP)

  • Connection Oriented

    • Three-way handshake to establish connection

  • Sequence Number

    • Reordering

  • Reliable Delivery

    • Retransmission

    • Time-out

  • Flow Control

    • Window Size

  • Application

    • HTTP, FTP, SMTP, Telnet

• User Datagram Protocol (UDP)

  • Connectionless

  • Unreliable Delivery

  • No Ordered Data Reconstruction

  • No Flow Control

  • Faster than TCP

  • Application

    • DNS, SNMP, VoIP

transport layer