Subject: Re: "dribbling bit"
To: None <>
From: Michael Richardson <>
List: tech-net
Date: 01/22/2003 18:10:34

>>>>> "seth" == seth  <> writes:
    seth> That's not what I meant.  In no sense can the ethernet encoding be viewed as
    seth> bits on the wire.  There is no simple explanation, but basically the
    seth> interpretation of the signal on the wire depends on the history of the signal.

  Yes, FastEthernet encodes as sequences of MII symbols in a star pattern,
like modems, of which 16 of them encode 4 bits of data at a
time. GigEthernet, depending upon the media does other various things.
  However, on FE, you can send a non-integral number of bytes, by sending an
odd number of nibbles.

  In this case, it is 10Mb/s UTP, so there really are 8 bit times worth of
data, with appropriate manchester encoding. As this goes into a ADSL box, 
and that box is *certainly* regenerating the signal on the wire (since it has
to shop it up in various ways to spread the bit errors over the FEC, and then
there is ATM encoding on top of that), it seems like some kind of cabling

  For what it's worth, I think it went away! I did change the cable, but that
didn't immediately help. It is next to a cold basement wall, and it has been
- -40, so...

]       ON HUMILITY: to err is human. To moo, bovine.           |  firewalls  [
]   Michael Richardson, Sandelman Software Works, Ottawa, ON    |net architect[
] |device driver[
] panic("Just another Debian GNU/Linux using, kernel hacking, security guy"); [
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