Physical Layer

The layer 1 of osi model moves bits between nodes. Electrical, mechanical, procedural, and functional requirements are defined at the Physical layer to assist with the activation, maintenance, and deactivation of physical connectivity between devices.

Other attributes of Layer 1 include the following:
  • Specification of voltage, wire speed, and pin-out cables
  • Capability to receive and transmit a data signal
  • Identification of the interface that is set up between the data terminal equipment (DTE) and the data communication equipment (DCE)
hubs at the physical layer
a hub is a really an multiple-port repeater. a repeater receives a digital signal and reamplifies or regenerates that signals and then forwards the digital signal out all active ports without looking at any data. an active hub does same thing. any digital signal received from a segment on a hub port is regenerated or reamplified and transmitted out all ports on the hub. This means all devices plugged into a hub are in the same collision domain as well as in the same broadcast domain.

Hubs, like repeaters, don't examine any traffic as it enters and is then transmitted out to the other parts of the physical media. Every device connected to the hub, or hubs, must listen if a device transmits. a physical star network where the hub is a central device and cables extends in all directions out from it. it is the type of toplogy a hub creates. Visually, the design really does resemble a star, whereas ethernet networks run a logical bus topology, meaning that the signal has to run through the network from end to end.

0 comments:

Post a Comment

 
created by www.mas-jet.blogspot.com | SUBTITLE | .SRT | ENGLISH