Computer Networking

Computer Networking

1. Application Layer

   • Overwiew
     • Transport services available to applications
       • Security
         • Encryption
         • Decryption
       • Reliable data transfer
       • Timing
       • Throughput
     • Client / Server
     • Peer-to-peer
   • Application Layer Protocols
     • HTTP - HyperText Transfer Protocol
       • Non-Persistant Connection
         • One handshake for each object
       • Persistant Connection
         • One handshake for all objects
       • Web Cashing
       • Pull protocol
     • SMTP - Simple Mail Transfer Protocol
       • Push protocol
       • POP3 - Post Office Protocol v.3
       • IMAP - Internet Mail Access Protocol
     • DNS - Domain Name Service
       • DNS Cashing
       • Non DNS Cashing
       • Root DNS servers
         • .com DNS server
           • Amazon.com DNS servers
         • .no DNS servers
           • vg.no DNS servers
         • .ord DNS servers
           • pbs.org DNS Servers
     • Peer-to-peer
       • Bittorrent
         • Tracker
           • For each torrent
         • Algorithm
           • Rarest First

2. Transport Layer

   • Analogy
     • Two houses on different sides of a country
   • Multiplexing
     • Add Socket
       • Dest. port
       • Source port
       • Application layer data
       • Other header flields
   • Demultiplexing
     • Remove socket
       • Application layer data
       • Source port
       • Dest. port
       • Other header fields
   • Reliable Data Transfer
     • Finale State Machine
       • Checksum
       • Positive and Negative acknowledgements
         • Duplicated ACKs
       • Secuence Numbers
       • Countdown Timer
   • Transport Layer Protocols
     • UDP - User Datagram Protocol
       • UDP segment structure (32 bit)
         • Header
           • Length
           • Checksum
             • Provides, but does not do anything to recover from an error
           • Dest. port
           • Source port
         • Data
           • Application Data (message)
       • No establishment of connection
     • TCP - Transport Control Protocol
       • Three-way Handshake
         • SYN
           • SYN ACK
             • ACK
       • MSS - Maximum Segment Size
         • 1460 bytes
       • TCP Serivce Quality
         • Reliable Data Transfer
         • In order data delivery
   • TCP Connection Management
   • Network Control
     • Flow Control
       • Control to not overflow memory in sender and receiver
       • Control the flow of the internet
     • Congestion Control
       • Guiding pricible
         • Lost segment
           • Timeout
             • Loss Event
               • Decrease sender`s rate of segments
           • 4 duplicate ACK
             • Loss Event
               • Decrease sender`s rate of segments
         • ACK segment arrives
           • Increase sender`s rate
       • Congestion Control Protocols
         • Congestion Avoidance
         • Fast Recovery
         • Slow Start

3. Network Layer

   • Overview
     • Forwarding
       • The fastest path for that spesific datagram.
     • Routing
       • Every step and desition on the way. Every little switch that takes place
     • Local Forwarding table
       • In every router. Exhange between routers to know whitch way is the fastest.
     • Network Service Model
       • Best-effort Service
   • Data Plane
     • Router
       • Inside the router
         • Input Port
         • Switching fabric
           • Methodes to switch packets
             • Memory
             • Bus
             • Interconnected Network
         • Output Port
       • Queuing
         • Input port
           • Switch fabric capasity to switch < Input Port`s processing speed
         • Output Port
           • Switch fabric capasity to switch > Output Port`s processing speed
       • Forwarding
         • Destination Based Forwarding
           • Forward be knowing the destination of a spesific package
         • Generalized Forwarding
           • Forward by knowing more information than just the destination
     • Packet Scheduling
       • FIFO - First in First Out
       • Priority Scheduling
       • Round Robin
       • WFQ - Weighted Fair Queuing
     • IP-addresse
       • IPv4 - Internet Protocol version 4
         • IPv4 Datagram (32 bit)
           • Version number
           • Header length
           • Type of service
           • Identifier flags, Fragmentation offset
           • Protocol
           • Source and Destination - IP-adresse
           • Data (segment)
           • Options
           • Time to live
           • Datagram length
           • Header checksum
         • Fragmentation
         • 192.32.216.9 = 11000001.00100000.11011000.00001001
       • DHCP
         • DHCP server discovery
         • DHCP server offcer(s)
         • DHCP request
         • DHCP ACK
       • IPv6 - Internet Protocol version 6
         • No fragmentation
         • No checksum
         • No options
         • IPv6 Datagram (128 bit)
           • Flow Lable
           • Payload length
           • Traffic Class
           • Next header
           • Hop limit
           • Version
           • Source and destination addresse
           • Data
         • Tunneling
   • Control Pane
     • Per-router control
       • BGP - Border Gate Protocol
       • OSPF - Open Shortest Path First
       • Routing is computed in each node
     • Logically centralized control
       • CA - Control Agents
         • Communicate with Controller
       • Routing is not computed at each node
     • Routing Algorithm
       • LS - Link state
         • Dijkstras
         • Needs to know link status of every node in the network
       • DV - Distant Vector
         • Each node talk to only its directly connected neighbors
       • AS - Autonomous Systems
         • Intra-AS routing protocol
           • OSPF - Open Shortest Path First
             • Dijkstra algorithm
           • Internal
         • Inter-AS routing protocol
           • BGP - Border Gate Protocol
             • BGP Connection
               • eBGP - External BGP
               • iBGP - Internal BGP
           • External

4. Link layer

5. Physical Layer

6. Overview

   • Packet Switching
     • Allocalte on Demand
   • Circut Switching
     • Pre allocated shared recourses
   • Encapsulation
   • Internet Protocol Stack
     • Mega Stor Drage Fanger
       • Message
       • Segment
       • Datagram
       • Frame
     • Application Layer
     • Transport Layer
     • Network Layer
     • Link Layer
     • Physical Layer
   • OSI-Modell
     • Application Layer
     • Presentation Layer
     • Session Layer
     • Transport Layer
     • Network Layer
     • Data Link Layer
     • Physical Layer
   • Calculate Traffic Intensity
     • Transmission Delay
     • Propagations Delay
     • Processing Delay
     • Queuing Delay