CCNA 200-301 Chapter 1
OSI model 7-1
Application, Presentation, Session, Transport, Network, Data Link, Physical
The process in which the device interprets the lower-layer headers and, when finished with each header, removes the header, revealing the next-higher-layer PDU.
de-encapsulation
A term referring to a data link header and trailer, plus the data encapsulated between the header and trailer.
Frame
PDU Layers
L7PDU, L6PDU, L5PDU, L4PDU, L3PDU, L2PDU
Encapsulation for TCP is?
Segment
Adjacent-Layer interaction
The general topic of how, on one computer, two adjacent layers in a networking architectural model work together, with the lower layer providing service to the higher layer.
Which of the following protocols are examples of TCP/IP data-link layer protocols? (Choose two answers.) a.Ethernet b.HTTP c.IP d.UDP e.SMTP f.TCP g.PPP
A and G. Of the remaining answers, IP is a network layer protocol, TCP and UDP are transport layer protocols, and SMTP and HTTP are application layer protocols.
The process of a web server adding a TCP header to the contents of a web page, fol-lowed by adding an IP header and then adding a data-link header and trailer, is an example of what? a.Data encapsulation b.Same-layer interaction c.OSI model d.All of these answers are correct.
A. Encapsulation is defined as the process of adding a header in front of data supplied by a higher layer (and possibly adding a trailer as well)
TCP/IP Model Layers 5-1
Application, Transport, Network, Data Link, Physical
The process of HTTP asking TCP to send some data and making sure that it is received correctly is an example of what? a.Same-layer interaction b.Adjacent-layer interaction c.OSI model d.All of these answers are correct.
B. Adjacent-layer interaction occurs on one computer, with two adjacent layers in the model. The higher layer requests services from the next lower layer, and the lower layer provides the services to the next higher layer.
The process of TCP on one computer marking a TCP segment as segment 1, and the receiving computer then acknowledging the receipt of TCP segment 1 is an example of what? a.Data encapsulation b.Same-layer interaction c.Adjacent-layer interaction d.OSI model e.All of these answers are correct.
B. Same-layer interaction occurs on multiple computers. The functions defined by that layer typically need to be accomplished by multiple computers—for example, the sender setting a sequence number for a segment and the receiver acknowledging receipt of that segment. A single layer defines that process, but the implementation of that layer on multiple devices is required to accomplish the function
Which OSI encapsulation term can be used instead of the term frame? a.Layer 1 PDU b.Layer 2 PDU c.Layer 3 PDU d.Layer 5 PDU e.Layer 7 PDU
B. The term frame refers to the data-link (that is, Layer 2) data structure created by a Layer 2 protocol. As a result, the matching OSI term for protocol data units (PDUs) mentions that same layer, that is, Layer 2 PDU, or L2PDU
Which of the following protocols are examples of TCP/IP transport layer protocols? (Choose two answers.) a.Ethernet b.HTTP c.IP d.UDP e.SMTP f.TCP
D and F. Of the remaining answers, Ethernet defines both physical and data-link proto-cols, PPP is a data-link protocol, IP is a network layer protocol, and SMTP and HTTP are application layer protocols.
Which of the following terms is used specifically to identify the entity created when encapsulating data inside data-link layer headers and trailers? a.Data b.Chunk c.Segment d.Frame e.Packet
D. By convention, the term frame refers to the part of a network message that includes the data-link header and trailer, with encapsulated data. The term packet omits the data-link header and trailer, leaving the network layer header with its encapsulated data. The term segment omits the network layer header, leaving the transport layer header and its encapsulated data.
The placement of data from a higher-layer protocol behind the header (and in some cases, between a header and trailer) of the next-lower-layer protocol. For example, an IP packet could be encapsulated in an Ethernet header and trailer before being sent over an Ethernet.
Encapsulation
Encapsulation for all Data
Frame
A generic term referring to any set of protocols and standards collected into a comprehensive grouping that, when followed by the devices in a network, allows all the devices to communicate. Examples include TCP/IP and OSI.
Networking Model
Adjacent-layer interaction on the same computer
On a single computer, one layer provides a service to a higher layer. The software or hardware that implements the higher layer requests that the next lower layer perform the needed function.
A generic term from OSI that refers to the data, headers, and trailers about which a particular networking layer is concerned.
PDU
A logical grouping of bytes that includes the network layer header and encapsulated data, but specifically does not include any headers and trailers below the network layer.
Packet
Encapsulation for IP is?
Packet
Same-layer interaction on different computers
The two computers use a protocol to communicate with the same layer on another computer. The Protocol defines a header that communicates what each computer wants to do
The communication between two networking devices for the purposes of the functions defined at a particular layer of a networking model, with that communication happening by using a header defined by that layer of the model. The two devices set values in the header, send the header and encapsulated data, with the receiving devices interpreting the header to decide what action to take.
same-layer interaction