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New Member

IP over ATM

How an IP packet of 100 bytes is segmented to

ATM cells, assuming routed PDU encapsulation?

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New Member

Re: IP over ATM

I'm not intimately familiar with the process but this is what I know: ATM operates at Layer 2.

The process is called Segmentation and Reassembly (SAR). The IP packet is broken down into 48-byte

segments. A 5-byte header (which contains the VPI/VCI addressing info) is attached to each segment to create a 53-byte cell. The 53-byte cell is switched to its destination. The destination then

reassembles the packet by removing the 5-byte header from each cell. The SAR encapsulation process is independent and invisible from the upper layers.

There is a great ATM website: http://www.atmforum.com

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