MC92500ZQ 데이터 시트보기 (PDF) - Motorola => Freescale

부품명

상세내역

일치하는 목록

MC92500ZQ

ATM Cell Processor

Motorola => Freescale 

1. ATM NETWORK

1.1 ATM Network Description

A typical ATM network consists of user end stations

that transmit and receive 53-byte data cells on virtual

connections (see Figure 1). The virtual connections are

implemented using physical links and switching sys-

tems that interconnect them. The specific combination

of physical links that implements a virtual connection is

chosen when the connection is established. On a given

physical link, each connection is assigned a unique

connection identifier. The connection identifier is

placed in the header of each cell by the transmitting

equipment and is used by the receiving equipment to

route the cell to the next physical link on the connection

path. All cells belonging to a specific virtual connection

follow the identical path from the transmitting end sta-

tion through the switching systems to the receiving end

station.

Each switching system handles multiple physical links

and transfers each arriving ATM cell from its source link

to its destination link according to the pre-arranged

routing for the connection to which the cell belongs. The

switching system consists of a switch fabric, which han-

dles the actual routing of the cells, and a line card for

each physical link (or group of links) to interface be-

tween the physical medium and the switch fabric. The

line card recovers incoming cells from the arriving bit

stream and converts outgoing cells into a bit stream for

transmission.

ATM standards divide the tasks to be performed on

each side of the switch fabric into PHY-layer and ATM-

layer tasks. The PHY-layer tasks are dependent on the

physical medium used to connect the switching

systems, while the ATM-layer tasks operate at the cell

level and are independent of the physical medium.

Therefore, it is logical to implement the PHY-layer and

ATM-layer functions on separate devices. In this case

the line card appears as in Figure 2. There are one or

more PHY-layer devices, an ATM-layer device, and

clock recovery devices to clock the PHY devices in

accordance with the signals arriving on the physical

media.

End

Stations

VCs

Switch

Switch

Switch

Switch

Switch

Switch

VCs

End

Stations

Switch

Line

Card

Switching Fabric

Line

Card

Clk Rec

PHY

MC92500

ATM Layer Functions

Line Card

Figure 2. MC92500 in an ATM Network Application

MC92500

MOTOROLA

3

Share Link: