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Home > Archive > CCNA > June 2002 > FTP? What layer?
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| aschifman 2002-06-11, 5:47 pm |
| What layer does FTP happen at? I think it is the application layer.
What do you think? | |
| Edmart 2002-06-11, 5:53 pm |
| yep | |
| darthfeces 2002-06-11, 9:32 pm |
| The OSI, or Open System Interconnection, model defines a networking framework for implementing
protocols in seven layers. Control is passed from one layer to the next, starting at the application layer in one
station, proceeding to the bottom layer, over the channel to the next station and back up the hierarchy.
Application
(Layer 7)
This layer supports application and end-user processes. Communication partners are
identified, quality of service is identified, user authentication and privacy are considered,
and any constraints on data syntax are identified. Everything at this layer is
application-specific. This layer provides application services for file transfers, e-mail, and
other network software services. Telnet and FTP are applications that exist entirely in the
application level. Tiered application architectures are part of this layer.
Presentation
(Layer 6)
This layer provides independence from differences in data representation (e.g.,
encryption) by translating from application to network format, and vice versa. The
presentation layer works to transform data into the form that the application layer can
accept. This layer formats and encrypts data to be sent across a network, providing
freedom from compatibility problems. It is sometimes called the syntax layer.
Session
(Layer 5)
This layer establishes, manages and terminates connections between applications. The
session layer sets up, coordinates, and terminates conversations, exchanges, and
dialogues between the applications at each end. It deals with session and connection
coordination.
Transport
(Layer 4)
This layer provides transparent transfer of data between end systems, or hosts, and is
responsible for end-to-end error recovery and flow control. It ensures complete data
transfer.
Network
(Layer 3)
This layer provides switching and routing technologies, creating logical paths, known as
virtual circuits, for transmitting data from node to node. Routing and forwarding are
functions of this layer, as well as addressing, internetworking, error handling, congestion
control and packet sequencing.
Data Link
(Layer 2)
At this layer, data packets are encoded and decoded into bits. It furnishes transmission
protocol knowledge and management and handles errors in the physical layer, flow
control and frame synchronization. The data link layer is divided into two sublayers: The
Media Access Control (MAC) layer and the Logical Link Control (LLC) layer. The
MAC sublayer controls how a computer on the network gains access to the data and
permission to transmit it. The LLC layer controls frame synchronization, flow control and
error checking.
Physical
(Layer 1)
This layer conveys the bit stream - electrical impulse, light or radio signal -- through the
network at the electrical and mechanical level. It provides the hardware means of sending
and receiving data on a carrier, including defining cables, cards and physical aspects. Fast
Ethernet, RS232, and ATM are protocols with physical layer components. | |
| ciscoteacher 2002-06-12, 7:53 am |
| Agreed. Applications like FTP, TFTP, and telnet all "occur" at layer 7. | |
| aschifman 2002-06-12, 5:42 pm |
| quote:
Originally posted by darthfeces
The OSI,
Awsome!
Thanks!! | |
| darthfeces 2002-06-12, 6:31 pm |
| yeah, it's like cool or something |
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