--- establishes a new virtual circuit every time an endpoint wants to connect to another endpoint.

SVC

A cell is a small data unit of variable size. T/False?

F.

Of fixed size.

AAL = ---

and has 4 types of data streams, which are ---

Application adaptation layer.

CBR, constant bit rate.

VBR, variable…

Connection oriented packet data.

Connection-less packet data.

AAL3/4 are both for --- -oriented packet data while AAL5 is ITU-T’s hot little number for point-to-point transmissions (in contrast to multi-point or internetwork ones). The sublayer designed to meet the needs for AAL5 is called ---

Connection.

SEAL, = simple and effective adaptation layer.

Anyone for alphabet soup??

Connection between 2 end points is accomplished through TPs (= ?), VPs (= ?), and VCs (= ?).

Transmission paths.

Virtual paths.

Virtual circuits.

Tasty, wasn’t it?

As a network expands (more/less) data is carried in headers

More (unless using ATM)

Asynchronous means --- in the context of TDM.

Flexible time slots allocated to each sending device. Not fixed.

ATM stands for ---

And it is ---

Asynchronous transfer mode

A cell relay protocol that allows high-speed interconnections.

ATM uses 2 types of connections. Help me out by telling me what they are.

PVC and SVC.

And they stand for???

CBR is the right type of data stream for applications with --- delays.

[ This is AAL1. ]

Minimal.

And transmission must simulate real time.

DEMUX =

De-multiplexer. Sexy, eh?

Easy one this time.

Name the 3 layers defined by the ATM standard, from the top down.

Application adaptation layer.

The ATM layer.

The physical layer.

If the user access devices, called ---  ---, are connected through ----, then how are the switches connected?

End points.

UNI = user to network interface.

NNI = network to network interfaces.

In a ---  ---, data are loaded into identical cells that can be transmitted with complete (predictability / uniformity).

Cell network.

Both.

In addition to dividing the AAL by category, the ITU-T also divides it by function. So each of the AAL categories is actually 2 layers, named --- and ---

Convergence sublayer (= CS)

Segmentation and reassembly sublayer (= SAR).

In synchronous TDM the MUX allocates (exactly the same amount / different  amounts) of time to each device – whether it’s got anything to send or not.

Same.

K.E. Batcher did something very clever to the Bannyan switch. What?

And don’t say invented the Batcher-Bannyan switch !!

KE designed a switch that comes before the Bannyan switch and sorts the incoming calls according to their final destination. To avoid cells colliding (bang! Bang! – it’s so noisy!).

The B-B switch uses “hardware merging techniques”.

K.E. Batcher question 2:

Another hardware module is added between the 2 B’s. What is it?

The trap module is inserted, to prevent “duplicate cells” (= cells with the same destination) from passing to the Bannyan switch simultaneously.

Layers. How many (and which) layers does ATM use?

ATM layer, and

physical layer.

Many of the problems associated with packet internetworking are solved by adopting ---

Cell networking.

Name 2 goals that ATM achieves.

And you get a bonus pat on the back for more than 2 !!

Fast data transmission

Reliable – less susceptible to noise degradation

Interface with existing systems

Low cost

Is connection-oriented

It moved as many operations to hardware as possible.

PVC = ---

Permanent virtual circuit.

So what does asynchronous TDM do about cells that would be empty?

Fills them with data from other channels, that’s what. So we say that asynchronous TDM allocated time slots “dynamically”.

Memory hook: Async is Dynamic.

SVC = ---

Could it be switched virtual circuit, I wonder.

T/False?  ATM uses asynchronous TDM.

T.

T/False?  Differing packet lengths make traffic unpredictable

T, before ATM

T/False?  The AAL allows existing networks such as packet networks to connect to ATM facilities.

T.

T/False?  The VPI is changed by the switch as a cell goes through the switch.

T. The switch consults its “switching table” to know where to send it.

Bonus answer: VCI works the same way.

TDM =

Time division multiplexing.

Ah but can you explain it??

TDM can be implemented in 2 ways, which are ---

Synchronous TDM

Asynchronous TDM

TDM is a digital process than can be applied when ---

Data rate transmission capacity of the transmission medium > data rate of the sending and receiving devices. So there is spare capacity in the medium. So multiple transmissions can happen at once.

The basic data unit in an ATM network is called a --- and it is 53 bytes long, 5 of them being allocated to ---

So what fills up the other bytes, eh?

Cell.

A header, with VPI and VCI – they define the transmission path for the cell from end point to end point.
Payload.

The data streams coming into a MUX are called ---

Channels.

MUX= multiplexer.

The length of the VCI is the same when it interfaces with NNI and UNI. T/False?  

T. both 16 bits long.

The length of the VPIs for UNI is ---

And for NNI is ---

(Don’t ya just love this sorta stuff??)

8 and 12.

Just remember VPs (vice presidents) drive V8s, the car engine.

The physical connection between an end point and a switch, or 2 switches, is called ---

Examples please.

TP (transmission path).

Wire, cable, satellite.

The simplest type of switch for ATM is the --- which has --- at each crosspoint.

Crossbar.

Microswitches (transistors).

The switch has a clock that delivers one cell to the output at each ---

Tick.

(Easy question! You liked that, didn’t ya?)

Time slots in synchronous TDM are grouped into frames, each frame consisting of ---

One cycle of time slots, one or more dedicated to each sending device. But if one is empty, bandwidth is wasted. Oh dear! We’ll have to fix that! But how? – look for the question on Asynchronous TDM...

To achieve an approximation of a continuous stream of data, use what?

And why does this work?

Cell networking.

Because links are high speed, and cells are small.

To get the most out of broadband technology, traffic must be ---

Time division multiplexed onto shared paths.

VBR data is where apps generate and consume data at variable rates, within ---

[ This is AAL2. ]

established parameters.

VC is inside VP, inside TP. Explain.

A lot of virtual connections (VCs) can be bundled inside one virtual path (VP) for transmission along one transmission path (TP). Simple as toast! (Hey, I gotta have some fun too.)

VP provides 1+ connection/s between ---

2 switches.

VPI = ?

VCI = ?

Virtual path / circuit identifiers.

What are interleaved as they are transmitted? And why?

Cells in cell networking.

So there are no long delays.

What factor is it that allows switches and terminals to treat each cell as a unit rather than as a bit stream?

The predictability produced by cells being of a fixed size. Makes it cheap and efficient.

What’s the name of this multistage switch with microswitches at each stage? These microswitches route cells based on the output port represented as a binary string.

Bannyan.

Which AAL data type might get dropped if it’s not very careful?

AAL2, the variable bit-rate one.

With crossbar switches, 2 cells can arrive at a crosspoint at the same time. The solution to this is ---

The Bannyan switch.

Must be important – it had 6 slides!