[question from a beginner] line cards

[Mark]

Hello

wikipedia describes line cards as typically used in telephone exchange
systems to terminate connections. With regard to this I have two questions:

1) are there line cards used in Ethernet equipment? As for my knowledge, a
lot of Layer 2 switches have hot-swap modules on-board, supporting fiber
connections ec. Are they classified as line cards as well ?
2) what does "terminate connections" mean? Does it mean that a data stream
doesn't pass beyond the line card, or it implies something different?

Thanks.

--
Mark

[Dick Wesseling]

In article <henajo$bi4$1...@aioe.org>,

It implies something different. See

http://en.wikipedia.org/wiki/Characteristic_impedance
http://en.wikipedia.org/wiki/Transmission_line

Without termination electrical signals that reach the end of a transmission
line would reflect at the end of the line and interfere with the original
signal. Terminating the line with a resistor of the proper value dampens
the echo.

[Mark]

Dick Wesseling wrote:
>
> It implies something different. See
>
> http://en.wikipedia.org/wiki/Characteristic_impedance
> http://en.wikipedia.org/wiki/Transmission_line
>
> Without termination electrical signals that reach the end of a
> transmission line would reflect at the end of the line and interfere
> with the original signal. Terminating the line with a resistor of the
> proper value dampens the echo.

I think this can be a part of functionality, but has nothing to do with "TCP
termination" which also may be a part of functions performed by the line
cards.

--
Mark

[David Schwartz]

On Nov 26, 5:39 pm, "Mark" <mark_cruzNOTFORS...@hotmail.com> wrote:

> wikipedia describes line cards as typically used in telephone exchange
> systems to terminate connections. With regard to this I have two questions:

> 1) are there line cards used in Ethernet equipment? As for my knowledge, a
> lot of Layer 2 switches have hot-swap modules on-board, supporting fiber
> connections ec. Are they classified as line cards as well ?

Yes, but there are some significant differences as well.

> 2) what does "terminate connections" mean?  Does it mean that a data stream
> doesn't pass beyond the line card, or it implies something different?

In this context, it means that the line card is the logical end of the
data connections on the links to and from the line card. That term is
typically not used with switch or router line cards because they don't
terminate the logical data connections.

DS

[Mark]

David Schwartz wrote:
>> wikipedia describes line cards as typically used in telephone
>> exchange systems to terminate connections. With regard to this I
>> have two questions: 1) are there line cards used in Ethernet
>> equipment? As for my knowledge, a lot of Layer 2 switches have hot-
>> swap modules on-board, supporting fiber connections ec. Are they
>> classified as line cards as well ?
>
> Yes, but there are some significant differences as well.

What are those, could you give some details or good web links ?

--
Mark

[David Schwartz]

On Nov 27, 12:18 am, "Mark" <mark_cruzNOTFORS...@hotmail.com> wrote:

> > Yes, but there are some significant differences as well.

> What are those, could you give some details or good web links ?

They're pretty obvious. Both types of line cards terminate the
physical connection. And both types of line cards provide for
configuring and monitoring the physical link. But telephone equipment
line cards typically terminate the logical links as well, while
network equipment line cards typically do not.

DS

[awstiver]

In telephone equipment, the line card provides the control logic to set
up and tear down telephone calls, provide ringing, addressing (telephone
number, for example), and other control functions. The exact functions
provided by the line card depend on whether the telephone line is analog
or digital, and for digital lines is pretty much vendor-specific.

"Line cards" in an ethernet switch, like a Cisco 6500 for example, are
basically a collection of ethernet ports on a module - a switch on a
card, for want of a better description. While they provide for the
physical connection and the necessary voltage levels, etc., such
functions as network addressing are controlled by the end device
(computer, etc.), and there is no equivalent in data communications for
many of the functions provided by telephone line cards. And, they are
all standards-based, so that it doesn't matter who made either the line
card or the devices you connect to it, they will work together.