--- protocols cuts the whole bit stream into same size characters.

Synchronous = same sized bits.

[ memory hook: SSS ]

Asynchronous protocols …

treat each character in a bit stream independently. Is therefore slower because of start/stop bits and variable length gaps between characters.

Bit-oriented protocols. Give examples.

SDLC, HDLC, LAPs, LANs.

Can frames be any size?

Yes

Configuration of a communications system is defined as ---

The 3 types are ---

= relationship of hardware devices on a link and can be unbalanced (1 device is a 1, other/s are 2), symmetrical (each physical station = 2 logical stations with cables between each 1-2 and 2-1), balanced (both stations in a p-p topology are of combined type; multipoint not allowed).

Data link protocols are in 2 groups which are…

Define terms.

Asynchronous which treats each character in a bit stream independently.

Synchronous protocols which cuts the whole bit stream into equal size characters.

Frames have 4 functions which are…

physical addresses (sender and/or receiver)

flow control

error control

access control

HDLC = ---, and was developed by ---

High-level data link control was based on SDLC and developed by ISO.

HDLC is a --- oriented protocol designed to support ---

bit-oriented

Both half-duplex (2 way at diff times) and full-duplex (2 ways at once) over point-to-point and multipoint links.

Line discipline is ---

A function of the data link layer which oversees the estab of links and transmission rights for devices.

Master/slave config is also known as ---

Unbalanced. One device is primary, other/s are secondary. Often this is multipoint.

Modems use which protocol?

Asynchronous, which is slower because of start/stop bits and variable length gaps between characters.

[ SAS = stop asynchronous start ]

Node to node delivery is the responsibility of which layer?

Data link.

p-p [my abbreviation ]

Point to point topology.

Protocols governing synchronous transmission systems can be divided into 2 classes:

Character-oriented protocols

Bit-oriented

Response mode is ---

Name and define the 3 types.

= relationship between 2 devices in an exchange, describes who controls the link).

There are 3:

normal (NRM, 2 must have permission from 1 to transmit),

asynchronous (ARM, permission not needed – data goes first to 1),

asynchronous balanced (ABM, all are combined, either may transmit without permission to other station).

SDLC = ?

Invented by ?

Synchronous data link control

IBM

Synchronous =

Synchronous protocols which cuts the whole bit stream into equal size characters.

Synchronous = same sized bits.

[ SSS ]

Systems using HDLC can be characterised by these 3 variables, ---

System types: primary (controls the link, issues commands), secondary (issues responses), and combined (can behave as either).

Config

Response mode.

The data link layer handles --- to --- delivery with error --- and --- control.

node node correction flow

Transparency problems occur when ---

Which protocol avoids this?

Binary data is interpreted as control code.

Bit-oriented.

What is framing and where does it happen?

Framing = dividing the bitstream from the network layer into manageable data units. Done in the data link layer.

Which is less efficient and therefore used less: bit or character oriented protocols?

Character.

Which is speedier: synchronous or asynchronous transmission?

S is speedier.