Chapter 1

Question 1

Networking Model

Answer 1

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 the devices to communicate.

Question 2

Protocol Data Unit (PDU)

Answer 2

An OSI term to refer generically to a grouping of information by a particular layer of the OSI model. More specifically, an LxPDU would imply the data and headers as defined by Layer x.

Question 3

de-encapsulation

Answer 3

On a computer that receives data over a network, 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.

Question 4

encapsulation

Answer 4

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.

Question 5

Adjacent-layer interaction

Answer 5

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 level preform the needed function.

Question 6

Frame

Answer 6

Data Link layer (LH, LT, Ethernet, PPP) header and trailer around Data, L2PDU.

Question 7

Segment

Answer 7

Transport layer (TCP, UDP) header and Data, L4PDU. In Ethernet, it is either a single Ethernet cable or a single collision domain.

Question 8

Same-layer interaction

Answer 8

The two computers use a protocol to communicate with the same layer on another computer. The protocol defined by each layer uses a header that is transmitted between the computers, to communicate what each computer wants to do.

Question 9

Packet

Answer 9

A logical grouping of bytes that includes the network layer header and encapsulated data, but specifically does not include any headers or trailers below the network layer.