Data communication
method occurs in two ways:-
- Broadcast
- Tokenpass
Ethernet
uses broadcast method of communication.
Logical Topologies:-
Logical Topologies:-
- Bus topology eg ethernet hub
- Token ring topology
- Hub and spoke topology.
Ethernet Hub is a shared media
,collision may happen in shared media
Collision Domain :-
Area affected(shared media) by unicast data or communication.To avoid collision,ethernet has adapted CSMA/CD(carrier sense multiple access/collision detction).
Collision Domain :-
Area affected(shared media) by unicast data or communication.To avoid collision,ethernet has adapted CSMA/CD(carrier sense multiple access/collision detction).
CSMA/CD
(Carrier Sense Multiple Access / Collision Detection) is the protocol used in
Ethernet networks to ensure that only one network node is transmitting on the
network wire at any one time.Carrier Sense means that every Ethernet
device listens to the Ethernet wire before it attempts to transmit. If the
Ethernet device senses that another device is transmitting, it will wait to
transmit.Multiple Access means that more than one Ethernet device can be
sensing (listening and waiting to transmit) at a time.Collision Detection
means that when multiple Ethernet devices accidentally transmit at the same
time, they are able to detect this error.
How Collisions Occur under CSMA/CD
Imagine a very simple Ethernet network with only two
nodes.
Each node, independently, decides to send an Ethernet frame to the other node.
Both nodes listen to the Ethernet wire and sense that no carrier is present.
Both nodes transmit simultaneously, causing a collision.
Both nodes detect the collision and each node waits a random amount of time before transmitting again.
Collisions are normal on an Ethernet network. A small amount of collisions are expected in the protocol design.
If too many nodes are transmitting on an Ethernet network the number of collisions can rise to an unacceptable level. This can reduce the amount of available bandwidth on an Ethernet network because so much bandwidth is lost in re transmission.
Ethernet switches greatly reduce the already minor difficulties experienced with the CSMA/CD protocol.
Types of Network:-
- Broad cast Multi access network ---Ethernet lan
- Non Broadcast Multi access network
- point to point network
- Point to multi point network.
Micro segmentation:-The
process of connecting source port and destination port in switch is known as micro
segmentation.
Layer 2 broadcast addresses is FF-FF-FF-FF-FF-FF.
Mac Address Structure:-
A Media Access Control address (MAC address) is a unique identifier assigned to network interfaces for communications on the physical network segment. MAC addresses are used for numerous network technologies and most IEEE 802 network technologies including Ethernet. Logically, MAC addresses are used in the Media Access Control protocol sub-layer of the OSI reference model.
Layer 2 broadcast addresses is FF-FF-FF-FF-FF-FF.
Mac Address Structure:-
A Media Access Control address (MAC address) is a unique identifier assigned to network interfaces for communications on the physical network segment. MAC addresses are used for numerous network technologies and most IEEE 802 network technologies including Ethernet. Logically, MAC addresses are used in the Media Access Control protocol sub-layer of the OSI reference model.
Token Ring:-
Token ring local area network (LAN) technology is a local area network protocol which resides at the data link layer (DLL) of the OSI model. It uses a special three-byte frame called a token that travels around the ring. Token-possession grants the possessor permission to transmit on the medium. Token ring frames travel completely around the loop.
Token ring local area network (LAN) technology is a local area network protocol which resides at the data link layer (DLL) of the OSI model. It uses a special three-byte frame called a token that travels around the ring. Token-possession grants the possessor permission to transmit on the medium. Token ring frames travel completely around the loop.
This concept was introduced by physical topology ring
topology.
FDDI:-
FDDI (Fiber-Distributed Data Interface) is a standard for data transmission on fiber optic lines in that can extend
in range up to 200 km (124 miles). The FDDI protocol is based on the token ring
protocol. In addition to being large geographically, an FDDI local area network
can support thousands of users.
An FDDI network contains two
token rings, one for possible backup in case the primary ring fails. The
primary ring offers up to 100 Mbps
capacity. If the secondary ring is not needed for backup, it can also carry
data, extending capacity to 200 Mbps.
The single ring can extend the maximum distance; a dual ring can extend 100 km
(62 miles).
FDDI is a product of American National Standards
Committee X3-T9 and conforms to the open system interconnect (OSI) model of
functional layering. It can be used to interconnect LANs using other protocols.
FDDI-II is a version of FDDI that adds the capability to add circuit-switched
service to the network so that voice signals can also be handled. Work is
underway to connect FDDI networks to the developing Synchronous Optical
Network.
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