There are 7 layers in the OSI model which are
from top to bottom:
application layer / presentation layer / session layer / transportation layer / network layer / data link layer / physical layer
OSI stands for Open system interconnection model. Application layer is the seventh layer in OSI model.
Data link layer
Networking layer of the OSI model
In the OSI reference model, that would be layer 3 (network).In the OSI reference model, that would be layer 3 (network).In the OSI reference model, that would be layer 3 (network).In the OSI reference model, that would be layer 3 (network).
Packet switching is considered part of layer 3 of the OSI model.Packet switching is considered part of layer 3 of the OSI model.Packet switching is considered part of layer 3 of the OSI model.Packet switching is considered part of layer 3 of the OSI model.
hub work at physical layer of osi model
The top layer of the OSI model; Application
1. Repeaters (Operate at the OSI Physical Layer).2. Bridges (Operate at the OSI Data Link Layer).3. Routers {and Brouters} (Operate at the OSI Network Layer).
Repeaters operate at the physical layer of the OSI model.
TELNET
seven layers
A firewall generally works at layer 3 and 4 of the OSI model. Layer 3 is the Network Layer where IP works and Layer 4 is the Transport Layer, where TCP and UDP function. Many firewalls today have advanced up the OSI layers and can even understand Layer 7 - the Application Layer.