A switch is a multi-functional networking device that can operate within several OSI layers. Which layer can a switch not function in?
A.
1
B.
2
C.
3
D.
4
Explanation:
Switches do not operate in the Physical layer, OSI Layer 1. They make
packet forwarding decisions (Layer 2), and specific switches exist that make
decisions based upon Layer 3 and Layer 4 data information.
In the previous question, switches are characterized as a mixture of hubs and bridges. Provided explanation was: “Switches combine the technologies of hubs and bridges. They act as hubs by enhancing performance and act as bridges by distributing traffic to different
networks.” As it is known hubs are operating at the Physical Layer. At the same time while L2 and L3 switches are widely spread, L4 switches (to be precise, L7 switches) are much more rare thing. But all the switches must include the specifications of L1.
By the mere fact that the switch does frame to bit conversion to transmit data over the wire it is acting in a layer 1 capacity. The port itself when converting frames to Binary data is performing LAYER 1 functions. I agree with Alexander, While Layer 3 switches exist they are normally a feature upgrade of a device such as Cisco LAYER 3 switches which are IP enabled and act more like Ethernet only routers for routing packets between VLANS using routing protocols. I hardly consider those devices switches even since they are acting at layer 3.
I don’t like this question
I agree with the answer. A
In general, then, physical layer technologies are ones that are at the very lowest level and deal with the actual ones and zeroes that are sent over the network. For example, when considering network interconnection devices, the simplest ones operate at the physical layer: repeaters, conventional hubs and transceivers. These devices have absolutely no knowledge of the contents of a message. They just take input bits and send them as output. Devices like switches and routers operate at higher layers and look at the data they receive as being more than voltage or light pulses that represent one or zero.
Ref: http://www.tcpipguide.com/free/t_PhysicalLayerLayer1.htm
The question “Which layer can a switch not function in?” that mean a switch can has no function in Layer 1?