Routing & Network Hardware

A BASIC HUB

  • Definition: A Hub is a device that connects all the segments of the network together in a star topology Ethernet network.

  • Functionality:

    • Every device in the network connects directly to the hub through a single cable.

    • Used to connect multiple devices without segmenting a network.

NETWORK INTERFACE CARD (NIC)

  • Definition: A Network Interface Card (NIC) is installed in a computer to connect, or interface, the computer to the network.

  • Connection Features:

    • Provides the physical, electrical, and electronic connections to the network media.

    • Can be an expansion card or integrated into the computer’s motherboard.

    • Usually connects to the computer through expansion slots located on the motherboard allowing peripherals to be plugged in directly.

    • In notebook computers, NIC adapters can be connected through the printer port or a PC card slot.

BRIDGE

  • Definition: A Bridge is a network device that connects two similar network segments together.

  • Primary Function:

    • Keeps traffic separated on either side of the bridge.

    • Breaks up collision domains.

  • Collision Domains: Refers to the separate areas within a network where packets can collide with one another.

  • Broadcast Domain: One broadcast domain encompasses the network segments connected by the bridge.

SWITCH

  • Definition: Switches connect multiple segments of a network together, similar to hubs but with enhanced functionality.

  • Differences from Hubs:

    • Recognizes frames and pays attention to the source and destination MAC address of incoming frames.

    • Utilizes the specific port on which the frame was received.

ROUTER

  • Definition: A Router is a networking device that forwards data packets between computer networks.

  • Functionality:

    • Performs traffic directing functions on the Internet.

ROUTING

  • Definition: Routing refers to the actual forwarding of data packets between a source and destination.

  • Routing Table:

    • A data table stored in a router or network host that lists routes to particular network destinations and possibly metrics (distances) associated with those routes.

    • Routing tables can be created manually (Static Route) or automatically through DHCP (Dynamic Route).

STATIC VS. DYNAMIC ROUTING

  • Simple Host Configurations: Host computers with a single network card connect to the Internet through a single router, typically have no complex routing software requirements.

  • Protocols:

    • DHCP: Dynamic Host Configuration Protocol that assigns IP addresses to devices on a network automatically.

    • ARP: Address Resolution Protocol, responsible for mapping IP network addresses to the hardware addresses used by data link protocol.

  • Dynamic Routing Features:

    • DHCP and ARP can cope with additions of new hosts seamlessly.

  • Static Routing Advantages:

    • Easy, free, and does not consume any network bandwidth.

    • Limitations: Inflexible and incapable of adapting to changes in network topology or router failures.

STATIC ROUTING & DEFAULT ROUTES

  • Packet Routing Example:

    • Host A communicates with Host B through multiple hops via routers.

  • Visual Representation:

    • Network Addressing:

    • Host A: 199.165.145.17

    • Host B: 199.165.146.4

    • Router R1 and R2 involved in the data transmission.

  • Components of Packets:

    • Ethernet Header, IP Header, TCP Header, etc.

STATIC ROUTING TABLES

  • Host A Example:

    • To view the routing table for any host (Windows or Linux), use netstat -rn command.

  • Sample Routing Table:

             Network    |       Mask         | Next Hop

  • 199.165.146.0 | 255.255.255.0 | direct

  • 199.165.145.0 | 255.255.255.0 | Default

  •     0.0.0.0         |           -             | 199.165.146.1

  • 199.165.146.3 |           -             | Internet Router 2

PRIVATE NETWORK ROUTING & NAPT

  • Example Scenario: IP headers sent through the Ethernet from various hosts.

  • Components:

    • Domain Server (10.10.10.2) provides NAPT (Network Address Port Translation) services for local network hosts to connect to the Internet.

  • Packet Modification:

    • NAPT replaces the private network address of the host with its own IP address in the header.

    • Assigns a TCP port in the header to manage the return of packets.

DYNAMIC ROUTING PROTOCOL BASICS

  • Importance: Routing protocols define the rules used by a router to communicate routing information with neighboring routers.

  • Functionality: Dynamic routing protocols run on routers to discover networks and update their routing tables.

  • Administrative Advantage: Easier management compared to static routing; however, it consumes router CPU processes and bandwidth.

IGP (Interior Gateway Protocol) and EGP (Exterior Gateway Protocol)

  • IGP Definitions:

    • Includes Distance Vector, Link State, and Hybrid routing protocols.

  • EGP Definitions:

    • Primarily focuses on broader scale WAN routing, connects autonomous systems (AS).

    • Autonomous Systems defined as large networks with unified routing policies.

CLASSES OF IGP ROUTING PROTOCOLS

  • Distance Vector: Finds the best path based on distance and minimizes hops (packet traversals through routers).

  • Link State:

    • Creates multiple routing tables: one for neighbors, one for overall topology, and one for active routing.

  • Hybrid: Emphasizes merging advantages of distance vector and link state protocols. Example: EIGRP (Enhanced Interior Gateway Routing Protocol) which is Cisco proprietary.

CLASSES OF EGP PROTOCOLS

  • Utilization: Used by ISPs for connecting autonomous systems.

  • Border Gateway Protocol (BGP): Major EGP that modifies distance-vector techniques focusing on preferred paths over path costs. Utilizes hop-count as a metric and relies on reliable transport mechanisms (TCP).

SUMMARY OF IGPs AND EGPs

  • IGPs: Includes RIP, IGRP, EIGRP, OSPF.

  • EGPs: Mainly BGP.

  • Autonomous System Connections: Demonstrated through networking interactions between Autonomous Systems 1 and 2.