LAN Network provides the function of delivery of data across a wide variety of types of physical networks. Lan network works base on the Physical and data link layers in the OSI reference model that works together to make a data communication to happen in a good design of your networking environment. I will not discuss about OSI reference model here that will take pages in detail theoretical discussion.
LAN network consists of high speed network infrastructure at a single location used to deliver network applications and services. The lan network technology that is widely used is Ethernet LAN network due to their lower cost, ease of use and the ability to scale up to and past multi-gigabit speeds.
What lan network devices are commonly used in local area network infrastructure? Lan network devices that operates at layer 2 – data link layer are Bridge, Switch and ATM switch. A switch is a pure layer 2 switching devices that allow Ethernet bandwidth to be used more efficiently. They localize the impact of contention and data collisions on the network. They achieve this by dynamically learning the MAC addresses of devices on the LAN, then only forwarding the required datagram to the appropriate receiving device. A Bridge is the original definition of a switch does. While ATM switch is the ATM that has a switching capability. Lan network devices that operates at layer 1 are hubs or concentrators or sometimes they are called repeaters.
What is a typical lan network design?Two computers connected to share the internet at home is a very simple form of local area network. There are three categories of local area network base on the size of the network, small, medium and large redundant local area network.
Small Sized Lan Network Diagram
This is a small sized local area network; it can contain a switch and several computers. The server can function as everything from the data server; print server or even a DNS. This small sized lan network can be applied to small office home office (SOHO).
Medium Sized Lan Network Diagram
This is a medium sized lan network for a medium sized computer network which can contain 3 or more switches that can span to one or two inter network building. There is no redundancy system applied to this lan network.
Large Sized Lan Network Diagram
The more complex lan network design is shown above. This is a large sized redundancy lan network. The switches are arranged in a redundancy system with an efficient spanning tree protocol enabled to all the switches.
The typical lan network design above are not using Ethernet hubs, why? Hubs are not popular today and even the intelligent ones are considered to be legacy networking devices that do not utilize the lan network bandwidth efficiently. Because the hubs that function as multiport repeaters share the limited bandwidth amongst all devices on the network, defining a single collision and broadcast domain. This will finally result a large number of data collisions, station timeouts and data retransmission that leads to the poor performance of the network.
Therefore all the lan network should use switches which will greatly improve the throughput of Ethernet networks and greatly reduce the data collisions on the lan network. The following is the recommended standard for the switch to use in your lan network.
1. Provide a minimum 100 Mbps switched connectivity to the desktop.
2. Provide a 1Gigabit to servers (Exchange; Databases; DHCP Servers; File servers; and active directory DC) and inter-switch links (uplinks).
3. Support command line for telnet; snmp based management.
4. Support Spanning tree protocol (STP).
5. Support Virtual LAN’s (VLANs).
6. Support tuning the STP protocol on a per VLAN basis
7. Support link aggregation technologies.
VLANs allow the network to be easily segmented for management and/or security reasons. They also allow the flexibility for high density LAN’s to be built using the same switched hardware. Multiple switches can also be interconnected by using a VLAN trunking protocol to transparently connect VLANs.
Lan Network Segmentation
In the simple above diagram, the lan network is segmented by utilizing the VLAN support switches. In our previous scenario the lan network for Geology; Accounting and Workshop are segmented using VLAN.
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