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NETWORK LAYER - Coggle Diagram

- - - - not expect acknowledgments
      - not guarantee delivery of the packet
      - not know if the other device is operational or if it received the packet
      - reduced overhead since there is no mechanism to resend data that is not received
    - - IP is UNRELIABLE
        
        cannot retransmit after an error
        
        cannot realign out of sequence packets
        
        cannot manage or fix undelivered or corrupt packets
        
        must rely on other protocols for these functions
      - IP is MEDIA INDEPENDENT
        
        does not concern itself with the type of frame required at the data link layer or the media type at the physical layer
        
        can be sent over any media type: copper, fiber, or wireless
      - The network layer will establish the Maximum Transmission Unit (MTU)
        
        receives this from control information sent by the data link layer
        
        then establishes the MTU size
      - Fragmentation is when Layer 3 splits the IPv4 packet into smaller units
        
        IPv6 does not fragment packets
        
        Example
        
        : Router goes from Ethernet to a slow WAN with a smaller MTU
        
        causes latency
    - - not establish a connection with the destination before sending the packet
      - destination will receive the packet when it arrives, but no pre-notifications are sent by IP
      - If there is a need for connection-oriented traffic, then another protocol will handle this (typically TCP at the transport layer)
      - no control information needed (synchronizations, acknowledgments)
- - - - Increased address space – based on 128 bit address, not 32 bits
      - Improved packet handling – simplified header with fewer fields
      - Eliminates the need for NAT – since there is a huge amount of addressing, there is no need to use private addressing internally and be mapped to a shared public address
- - - - itself – 127.0.0.1 (IPv4), ::1 (IPv6)
      - local hosts – destination is on the same LAN
      - remote hosts – devices are not on the same LAN
    - - IPv6 – source uses the network address and prefix advertised by the local router
      - local traffic is dumped out the host interface
      - IPv4 – source uses its own IP address and Subnet mask, along with the destination IP address
      - remote traffic is forwarded directly to the default gateway on the LAN
  - - - must have an IP address in the same range as the rest of the LAN
      - can route to other networks
      - can accept data from the LAN and is capable of forwarding traffic off of the LAN
- - - - remote
        
        manually – with a static route
        
        dynamically – using a routing protocol to have the routers share their information with each other
      - default route
        
        forwards all traffic to a specific direction when there is not a match in the routing table
      - directly connected
        
        automatically added by the router, provided the interface is active and has addressing.