Routing & Switching Chapter 1: Fundamentals of WANs and IP Routing

Fundamentals of WANs and IP Routing

• A basic local area network (LAN) can be connected using a hub, which is an antiquated device that connects wires together.
• A switch can break up collision domains, resulting in a lot less network congestion.
• A router creates an internetwork and breaks up broadcast domains.

Internetworking Devices

• A router breaks up both broadcast and collision domains for every LAN interface.
• A switch only breaks up collision domains.
• A network with all these internetwork devices in place would have routers, switches, and other devices working together.

How IP Addressing Helps IP Routing?

• IP addressing helps IP routing by providing a unique address for each device on the network.
• This allows devices to communicate with each other and for routers to route traffic efficiently.

Protocols that Help IP Routing

• Domain Name System (DNS) resolves hostnames to IP addresses.
• Address Resolution Protocol (ARP) resolves IP addresses to Ethernet (MAC) addresses.

Physical Components of Network

• WLAN devices connect wireless devices to the network.
• Access Points (APs) allow wireless devices to connect to a wired network and extend a collision domain from a switch.
• WLAN Controllers manage access points in medium to large quantities.
• Firewalls monitor and control incoming and outgoing network traffic based on predetermined security rules.

OSI Model

• OSI model is a layered architecture that consists of seven layers.
• Each layer defines a set of functions that take part in data communication.
• The seven layers are:
  • Application Layer (Layer 7): provides an interface for users to interact with applications or networking services.
  • Presentation Layer (Layer 6): defines a standard format to the data.
  • Session Layer (Layer 5): establishes, maintains, and terminates sessions.
  • Transport Layer (Layer 4): provides data delivery mechanism between applications in the network.
  • Network Layer (Layer 3): provides logical addressing and path determination (routing).
  • Data Link Layer (Layer 2): provides reliable transit of data across a physical link.
  • Physical Layer (Layer 1): defines the electrical, mechanical, and functional specifications for communication between network devices.

Transport Layer

• The Transport Layer provides data delivery mechanism between applications in the network.
• The major functions described at the Transport Layer are:
  • Identifying service using port numbers.
  • Multiplexing and de-multiplexing.
  • Segmentation and reassembling.
  • Error correction.
  • Flow control.
• The protocols that work at the Transport Layer are TCP and UDP.

Network Layer

• The Network Layer provides logical addressing and path determination (routing).
• The protocols that work at the Network Layer are routed protocols (IP, IPX, AppleTalk) and routing protocols (RIP, OSPF).
• Routing protocols perform path determination (routing).

Data Link Layer

• The Data Link Layer has two sublayers: MAC (Media Access Control) and LLC (Logical Link Control).
• MAC provides reliable transit of data across a physical link and error detection using CRC (Cyclic Redundancy Check).
• LLC provides communication with the Network Layer.

Physical Layer

• The Physical Layer defines the electrical, mechanical, and functional specifications for communication between network devices.
• The functions described at the Physical Layer are:
  • Encoding/decoding: converting binary data into signals based on the type of media.
  • Electrical, mechanical, and functional specifications for communication between devices.