What is LAN?
LAN
stands for “Local Area Network” is a network that is contains within a limited
area, such as a single building (school, residence, laboratory, college,
university campus, office). Every computer connected to the network (via LAN)
is said to be “on the network”. The technical term for a computer that’s on the
network is a node. Local Area Network has the two most common technologies such
that Ethernet and Wi-Fi.
Types of LAN
There are
two types of LAN such that client/server LAN and
peer-to-peer LAN. A client/server LAN consists of several
devices (the clients) connected to a central server. The server manages file
storage, application access, device access, and network traffic. A peer-to-peer
LAN doesn't have a central server and cannot handle heavy workloads like a
client/server LAN can, and so they're typically smaller. On a peer-to-peer
LAN, each device shares equally in the functioning of the network. The devices
share resources and data through wired or wireless connections to a switch or
router. Most home networks are peer-to-peer.
What is Ethernet?
Ethernet is the
most common type of computer network used in local area network (LAN), a wide
area network (WAN), and a metropolitan area network (MAN). Therefore the
Ethernet has a standard packet format that all packets sent on an Ethernet
network must follow. An Ethernet packet contains the following information.
Ethernet Packet Information
- Preamble: The
preamble consists of 56 bits of alternating ones and zeros and is use to
synchronize the precise timing required to read packet data.
- Start-of-frame
marker: A start-of-frame marker is a single byte that
indicates that the frame is about to begin.
- Destination
MAC address (six bytes).
- Sender
MAC address (six bytes).
- Tag: The
tag, which is use to support virtual local area networks (VLANs), is
optional. Therefore a VLAN lets you divide two or more distinct LANs on a
shared physical infrastructure.
- Ethertype
(two bytes): This field indicates the specific protocol
that is contains in the payload.
- Payload: The
payload contains the actual data being sent by the packet. The payload can
be anywhere from 46 to 1,500 bytes. If the information that needs to be
sent is longer than 1,500 bytes, the information must be broken into two
or more packets, sent separately, and then reassembled when the packets
reach their destination. Therefore the tasks of breaking up and
reassembling the data are handle by protocols at higher layers in the OSI
framework. Ethernet itself has no understanding of what is in the packets
it sends.
- Frame
check sequence (four bytes): The frame check sequence (FCS) is used to
ensure that the frame data was sent correctly. Basically, the interface
that sends the packet uses an algorithm to calculate a four-byte number
based on the contents of the frame and saves this number in the FCS field.
When the packet is receive, the receiving interface repeats the
calculation, and then makes sure that the number recorded in the FCS
portion of the packet matches the number it calculated. If the numbers
disagree, the packet got garble in transmission and is discards.
What is Wi-Fi?
A Wi-Fi
is stands for “Wireless Fidelity” is a common name for wireless networking
technology. Wi-Fi Access Point that works with most 802.11 Wi-Fi standards and
protocols, including 802.11ac. They are commonly used for local area
network of devices and Internet access.
Also
learn about IP Routing
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