Packet Forwarding

On a Cisco device, IPv4 addresses configured can be viewed with the command show ip interface with the optional suffix of brief or a specific interface-id. The brief suffix shows a summarised view of the configured IP addresses on the device. The standard command can show a large amount of information such as the configured…

TCP/IP is the standard protocol for most networks. To begin with it was used with IPv4 (Internet Protocol Version 4) and it’s 32-bit IP addressing. IPv4s public IP address pool over the years has become exhausted with no longer any fresh spare IP addressing space to be given out. Options to get IPv4 address space…

Layer 3 forwarding can be broken down into two types: Forwarding traffic to devices within the same subnet Forwarding traffic to devices on a different subnet Forwarding to devices within the same subnet Two devices that wish to communicate on the same subnet can do so locally. As the source device begins to form the…

MAC Address Table The MAC addres table keeps a record of the switch ports and VLANs to which a network host is associated too. The switch builds its MAC address table by keeping track of the source MAC addresses of packets that it recieves through its ports. The information that the switch collects from these…

Trunk ports can carry multiple VLANs across a single port. Trunk ports are typically used when uplinking a multiple number of VLANs togerther from one network hardware device to another such as a switch or router over a single port to port connection. Switch ports on a Cisco Catalyst switch are configured with the command…

Access Ports Access ports are connected to only a single VLAN, and do not transmit the 802.1Q tags on any ports recieved or transmitted from the switch. This makes the VLAN tag invisible to any host devices that sit on the other end of the network cable. By default Cisco catalyst switches place all ports…

A router between sections of the LAN can help keep broadcast domains to a suitable size, providing efficient network communication. Virtual LANs help keep broadcast domains small by providing seperation between hosts on the same network switch. This can allow a network switch to be better utilised by providing different subnetworks across the same network…

The Ethernet protocol began with technologies known as Thinnet (10Base-2) and Thicknet (10Base-5), connecting all devices together using the same coaxial cable and jointed together using T-Connectors. By © Raimond Spekking / CC BY-SA 4.0 (via Wikimedia Commons), CC BY-SA 4.0, Link By © Raimond Spekking / CC BY-SA 4.0 (via Wikimedia Commons), CC BY-SA…

The data link link layer of the OSI midel handles the physical addressing underneath the network layer for communication between two hosts. Network packets include Layer 2 addressing with their unique source and destination addresses known as media access control or MAC addresses for ethernet. A MAC address is a 48-bit address split across six…

The primary function of the network is to provide connectivity between devices. In the past there was a huge variety of different network protocols but today almost everything is based on Traffic Control Protocol/Internet Protocol (TCP/IP). TCP/IP is based upon the Open Systems Interconnection (OSI) model that is made up of seven layers. Each layer…