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Interleaving is forward error correction. Your packet bits are spread in time and interleaved with bits from other packets, so that a noise spike has less chance of causing data loss. This is a design feature which makes video streaming (a la "video on demand) more robust. Remember that ADSL was originally developed for "cable TV on copper loops" but when that didn't take off it was (is) used for highspeed internet access. TCP/IP has it's own error correcting facilities and interleaving is not nearly as important. Fast Path (fastcells, fast switched) disables or greatly reduces the interleaving "spread" of the bits.

Decreased latency (ping times) can improve performance of streaming content and makes browsing more snappy. It can also help with FTP and other densely-packed file transfer protocols. Low pings are critical for online gaming.

If you changed over, you probably would not see any problems unless your line is marginal. TCP/IP retransmits packets which are corrupted and unless your line has high packet loss, can handle the occasional noise burst quite nicely. If you have a very noisy line your modem could lose sync, which is not good at all. This is unlikely.

On Ameritech, if your first and/or second hop into the network is well under about 60 ms (usually under 20) you are already on Fastpath. Interleaved lines will read about 60 ms or higher at hop 2 on a traceroute.

To get changed over, send a message to one of the SBC ASI techs (see /faq/7930 ), with the following information:
- Username
- Phone Number you used to sign up
- Service address
- Circuit ID number (on tag in NID or on sticker on front of folder you got when they connected you up) if you have it
- request to be changed from interleaving to fastpath

Note: If you are on line-shared self-install or were installed after September 5, 2000 you are already on fastpath.

Also see this thread. A good general explanation of the theory of Interleaving is here.

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by RadioDoc See Profile edited by lev See Profile
last modified: 2004-08-03 00:42:37