[question from a beginner] line cards

Nov 27, 2009 6 Replies
M

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.


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D

It implies something different. See

formatting link
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.

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M

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.

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D

Yes, but there are some significant differences as well.

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

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M

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

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D

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

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A

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.

"L> Hello

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