Building and Managing Networks

1. Network Addressing

IPv4 vs. IPv6: Structure and Differences

IPv4

  • An IPv4 address consists of 32 bits, e.g., 192.168.1.1.
  • Represented in decimal notation: four numbers between 0 and 255.
  • Limitation: Only about 4.3 billion addresses are available.

IPv6

  • An IPv6 address consists of 128 bits, e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334.
  • Written in hexadecimal: eight groups of four hexadecimal characters.
  • Advantage: Virtually unlimited addresses.

Subnetting and CIDR

Subnetting

  • Dividing a network into smaller subnets to use addresses efficiently.
  • Example: 192.168.1.0/24 represents 256 addresses in the subnet.

CIDR (Classless Inter-Domain Routing)

  • Enables flexible addressing without fixed classes (A, B, C).
  • Example: 192.168.1.0/27 = 32 addresses (30 usable).

Private vs. Public IP Addresses

  • Private Addresses: Local to the LAN, not directly accessible on the internet (e.g., 192.168.0.0/16).
  • Public Addresses: Directly reachable on the internet.

2. Network Design

Network Topologies

Star Topology

  • Each device is connected directly to a central switch.
  • Advantage: Failure of one device does not affect the network.

Ring Topology

  • Devices are connected in a ring.
  • Advantage: Equal load distribution, but failure of one device breaks the network.

Mesh Topology

  • Each device is connected to multiple other devices.
  • Advantage: High redundancy and fault tolerance.

VLANs (Virtual LANs)

  • Logical division of a physical network into multiple subnets.
  • Example: Separating IT and guest networks in a company.

3. Network Management

SNMP (Simple Network Management Protocol)

  • Allows monitoring and controlling network devices.
  • SNMP Components:
    • Manager: Monitors the network (e.g., Zabbix).
    • Agent: Runs on each monitored device.
    • MIB (Management Information Base): Database of manageable network parameters.

Network Monitoring

  • Tools like Nagios, Zabbix, or Prometheus provide detailed insights into network status.

QoS (Quality of Service)

  • Prioritization of traffic, e.g., for video calls or critical services.
  • Example: Reserving bandwidth for specific applications.

Conclusion

Network addressing and design are the foundations of efficient and secure networks. The next chapter will cover network security, including firewalls and VPNs.