basic info about cisco chassis, backplane, and line card...

1. What is Cisco Chassis, Backplane, and Line Card?
Chassis, You Know Here:
A Chassis is a frame/housing for mounting the circuit components for Cisco Switches
and Routers or any type of devices that provides power and a high-speed backplane.
The frame also protects all of the vital internal equipment from dust, moisture, and
tampering.
Making the Chassis to define even easier is;
A chassis is an enclosure; a container that holds things together... i.e. an egg carton
holds eggs together inside. A chassis does the same thing; it holds the important
things inside like wiring, power supplies etc.
Cisco Chassis
Cisco Backplane
General info of Backplane
Backplane is a circuit board with sockets that allows Supervisor engines Cards or
modules to be inserted into these sockets and connect them to each other.
Backplane is mounted on the Chassis.
Modules or line cards provide different types of interfaces, but the processing of
packets is usually done in the Supervisor engine. Backplane is the medium for data
flow between modules and Supervisor engines.
Additionally, most high-end switches off-load processing away from the supervisors,

2. allowing line cards to switch traffic directly between ports on the same card without
using any processing power or even touching the backplane. Naturally, this can't be
done for all traffic, but basic layer-2 switching can usually be handled exclusively by
the line card, and in many cases also more complex operations can be handled as
well.
What is Line Card?
The line cards provide interfaces to the network.
A line card can terminate a line supporting voice POTS service, ISDN service, DSL
service, or proprietary ones. Some line cards are capable of terminating more than
one type of service.
Since an access network element is usually intended to interface many users
(typically a few thousands) some exchanges have multiple line terminations per card.
Similarly, it is common to have many line cards in the same network element.
A line card or Digital Line Card is a modular electronic circuit on a printed circuit
board, the electronic circuits on the card interfacing the telecommunication lines
coming from the subscribers (such as copper wire or optical fibers) to the rest of the
telecommunications access network.
A line card commonly interfaces the twisted pair cable of a POTS local loop to the
public switched telephone network (PSTN). Telephone line cards used in PSTN
perform multiple tasks such as analog-to-digital and digital-to-analog conversion of
voice, off-hook detection, ring supervision, line integrity tests, and other BORSCHT
functions. In some telephone exchange designs the line cards generate ringing
current and decode DTMF signals. The line card in a Subscriber Loop Carrier is
commonly called a Subscriber Line Interface Card (SLIC).