Chapter 6: Network Layer

Chapter 6: Network Layer

1. Provides services to allow terminals to exchange data on the network.

   • Terminal Addressing:
     • The terminals must be configured with a unique IP address to identify them in the network.
   • Encapsulation:
     • The network layer encapsulates the protocol data unit (PDU) of the transport layer to a packet.
   • Routing:
     • The network layer provides services to direct packets to a destination host on another network. To transfer a packet to other networks
   • Decapsulation:
     • When the packet reaches the network layer of the destination host, the host checks the IP header of the packet.

2. Network layer protocols

   • Internet Protocol version 4 (IPv4)
     • IPv4 limitations
       • Depletion of IP addresses
       • Internet routing table expansion
       • Lack of complete connectivity
   • Internet Protocol version 6 (IPv6)
     • Greater address space
       • IPv6 encapsulation
       • IPv6 packet header
         • Version
         • Traffic class
         • Flow label
         • Content Length
         • Next Header
         • Jump Limit
     • Better package handling
     • The need for NAT is eliminated

3. IP encapsulation

   • To encapsulate the transport layer segment or other data, IP adds an IP header.

4. IP features

   • Without connection
     • IP has no connection, which means that an exclusive full connection is not generated before sending data
   • Minimum service
     • best effort or unreliable IP protocol delivery
   • Media independent
     • IP works independently of the means that carry the data in the lower layers of the protocol stack

5. The host forwarding decision

   • A host can send a packet to any of the following
     • Likewise
     • To the local host
     • To a remote I / O module

6. Default gateway

   • The default gateway is the network device that can route traffic to other networks

7. Tablas de routing de host

   • Interfaces list
   • IPv4 route table
   • IPv6 route table

8. Router packet delivery decision

   • Rutas conectadas directamente
   • Remote routes
   • Default route

9. Next hop address

   • When a packet destined for a remote network reaches the router, the router matches the destination network with a route in the routing table. If it finds a match, the router sends the packet to the next hop address of the identified interface.