Network Segmentation and Virtualization Notes

Objectives

  • TCP/IP Network Design: Understand unique design methods including subnetting, CIDR (Classless Inter-Domain Routing), and supernetting.
  • Virtualization: Explain virtualization and identify characteristics of virtual network components.
  • VLAN Techniques: Describe techniques for incorporating virtual components in VLANs (Virtual Local Area Networks).

Network Segmentation and Subnetting

  • Segmentation: Dividing a network into smaller networks.
    • Traffic Separation: Reduces traffic on a single network by creating multiple broadcast domains.
    • Benefits:
    • Enhances security
    • Improves performance
    • Simplifies troubleshooting
Understanding Subnet Masks
  • IPv4 Addresses: Consist of a Network ID and Host ID.
  • Subnet Mask: Helps determine which part of an IP address corresponds to the Network ID and which part corresponds to the Host ID.
    • More '1's in the subnet mask indicate more bits are used for the Network ID.
Default IPv4 Subnet Masks
Network ClassSubnet Mask (Binary)Default (Dotted Decimal)
A11111111 00000000 00000000 00000000255.0.0.0
B11111111 11111111 00000000 00000000255.255.0.0
C11111111 11111111 11111111 00000000255.255.255.0

CIDR (Classless Interdomain Routing)

  • CIDR Notation: IP address followed by / and the number of bits in the Network ID.
    • Example: 192.168.89.127/24 where 24 signifies the number of bits in the Network ID.

Advantages of Subnets

  • For growing networks, segmentation enhances the management of network traffic by separating larger networks into smaller, manageable parts, as evidenced by:
    • A company growing from 20-30 computers to hundreds.

Supernetting

  • Definition: Combining contiguous networks that share the same CIDR block into one supernet.
    • Benefits:
    • Reduces routing table entries
    • Facilitates creating a single network from multiple Class C licenses.

Subnetting in IPv6

  • Overview: Simpler than in IPv4, as it does not utilize classes or traditional subnet masks.
    • The first four blocks (64 bits) identify the network.
    • Example of route prefix: 2608:FE10::/32.

Virtualization

  • Definition: Emulates a computer or OS on a physical system, using Virtual Machines (VMs).
    • Components:
    • Host: The physical system.
    • Guest: Each VM.
    • Hypervisor: Software managing VMs.
  • Advantages:
    • Efficient resource use
    • Cost and energy savings
    • Simplified backups and replication
  • Disadvantages:
    • Complexity increases
    • Potential performance compromise
    • Licensing costs may increase

Virtual Network Components

  • A Virtual Network may consist solely of virtual machines on a physical server, integrating both physical and virtual elements.

Virtual Machines and Network Adapters

  • vNICs (Virtual Network Interface Cards): Each VM can have multiple vNICs, typically connected to a virtual switch upon creation. Each vNIC receives a MAC address automatically.

Virtual Switches and Network Connection Types

  • Bridged Mode: vNIC accesses the physical network using the host’s NIC, obtaining an IP address from DHCP.
  • NAT Mode: Virtual network relies on the host to act as the NAT device, obtaining IP info from the host.
  • Host-only Mode: Enables VMs on one host to communicate but isolates them from external networks.

VLAN Overview

  • VLAN: Groups ports on a switch, requiring a programmable physical switch.
    • 802.1Q Standard: Specifies how VLAN information is encapsulated in frames.
    • Each VLAN has its subnet and typically serves as its broadcast domain.
Benefits of VLANs
  • Enhance security, streamline traffic management, prioritize data handling, and segregate a large network into smaller ones.
STP (Spanning Tree Protocol)
  • Operates at Data Link layer to prevent broadcast loops by calculating paths to avoid loops and blocking links as needed.
Switch Configurations
  • Managed Switch: Requires configuration, IP assigned, supports VLANs.
  • Unmanaged Switch: Plug-and-play, no IP assigned.
Wireless VLANs
  • Centralized management of access points through Wireless Controllers, utilizing LWAPP or CAPWAP protocols.
Troubleshooting VMs and VLANs
  • Virtual networks can be managed similarly to physical networks but require specific adjustments for integration within VLANs.

Summary

  • Segmentation through subnets and VLANs enhances security, performance, and troubleshooting.
  • CIDR improves address management with network identifiers, and supernetting aggregates route entries.
  • IPv6 subnetting simplifies structure compared to IPv4. Virtualization introduces resource efficiency at the cost of complexity.