Chapter 6: Network layer

Chapter 6: Network layer

1. Network Layer Protocols

   • The network layer in communications
     • The network layer
       • Terminal Addressing
       • Encapsulation
       • Routing
       • Decapsulation
     • Network layer protocols
       • Internet Protocol version 4 (IPv4)
       • Internet Protocol version 6 (IPv6)
   • Characteristics of the IP protocol
     • IP encapsulation
       • IP adds an IP header. This header is used to deliver the package to the destination host.
     • IP features
       • It provides only the functions necessary to send a packet from a source to a destination through an interconnected network system.
     • IP: No connection
       • It means that an exclusive complete connection is not generated before sending the data.
     • IP: Minimum service delivery
       • The IP protocol does not guarantee that all packets that are sent, in fact, are received.
   • IPv4 Package
     • IPv4 packet header
       • The IPv4 packet header consists of fields that contain important information about the packet.
   • IPv6 Package
     • IPv4 limitations
       • Depletion of IP addresses
       • Internet routing table expansion
       • Lack of complete connectivity
     • Introduction to IPv6
       • IPv6 overcomes the limitations of IPv4 and represents a significant improvement with features that are better suited to current and predictable network demands.
     • IPv6 encapsulation
       • In IPv6 some fields remain the same, while others have changed their name and position, and some IPv4 fields are no longer necessary.
     • IPv6 packet header
       • Extension headers are optional and are located between the IPv6 header and the content.

2. Routing

   • How does the host arm the routes?
     • The host forwarding decision
       • Direct packets between hosts.
     • Default gateway
       • It is the network device that can route traffic to other networks.
     • Use of the default gateway
       • default gateway either dynamically of the DHCP protocol or if configured manually.
     • Tablas de routing de host
       • route print o netstat -r.
   • Router Routing Tables
     • Router packet delivery decision
       • When a host sends a packet to another, it uses its routing table to determine where to send it.
     • IPv4 router routing table
       • show ip route
     • Routing table entries directly connected
       • C
       • L
     • Remote network routing table entries
       • The routing table stores information about directly connected and remote networks.
     • 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.

3. Routers

   • Anatomy of a router
     • A router is a computer.
       • Cisco routers are designed to meet the needs of many different types of networks.
     • The router's CPU and OS
       • Cisco devices need a CPU to execute OS instructions.
     • Router memory
       • RAM
       • ROM
       • NVRAM
       • FLASH
     • Interior of a router
       • They all have the same general hardware components.
     • Router connection
       • Cisco switches, routers and devices interconnect many devices.
     • WAN and LAN interfaces
       • In-band router interfaces and administration ports.
   • Arranque del router
     • Router boot process
       • Realization of the POST and loading of the starting program.
       • Location and load of Cisco IOS.
       • Location and loading of the configuration file.
     • Bootset files
       • Switches such as Cisco routers load the IOS image and startup configuration file into RAM when started.

4. Cisco router configuration

   • Configuration of the initial parameters
     • Basic steps in configuring a switch
     • Basic steps in configuring a router
   • Interface configuration
     • Configure router interfaces
     • Interface Configuration Verification
   • Default Gateway Configuration
     • Default Gateway for a Host
     • Default gateway for a switch