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Re: Interface reality check

Dear Paul,

>  "Paul Bottorff" <pbottorf@xxxxxxxxxxxxxxxxxx> writes:
> Using the Ethernet TYPE field does not work in a practical design. First,
> the effect of errors in the TYPE field will alter the location of the CRC,
> in effect producing a huge burst error.  The large error will break
> the misdetected error probabilities. 

The TYPE field has 4-bit hamming protection.  The Mean Time to an
undetected TYPE error is over 60 billion years.

> Second, the Ehternet TYPE can not eliminate the overhead of the SA and
> DA before generating a new frame. 

That's true.  So you have some extra latency.

In any case, the Ethernet WAN phy does not need T1X1 capability.  It is
not intended to be a general replacement for SONET.  It is only a dedicated
wrapper for *pure* 10GbE streams.

This means that T1X1 support is really irrelevant to the WAN phy issue.

T1X1 will be used by SONET for what it was designed for.  THis includes
encapsulation of fiber channel,  and 10Meg, 100Meg and 1G Ethernet.  The
10GbE WAN phy is something entirely different.  In my understanding, there
is no desire or requirement for the 10GbE WAN phy to support encapsulation
of "alien" data streams.

Best regards,
Rick Walker