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Re: IPG variation rule


I agree with your specification. It fixes the ambiguity between the
imprecise text and the table, which represents a specific
implementation. I suggest changing the text per your recommendation and
leaving in the table in D1.1. The table may be removed in a later draft
as extraneous by comment.

Best Regards,

Juan Pineda wrote:
> Hi,
> I would like to propose a precise specificaiton of the IPG variation
> concept proposed in:
> >
> Haddock_1_0700 gives a table which embodies a specific implementation
> which satisfies the concept, but it does not provide a precise way to
> test whether other implementations might also satisfy the concept.  I
> believe that the specification proposed in this Email is consistant with
> haddock_1_0700, so this isn't a change in what haddock_1_0700 proposes,
> only a different way of stating it.  Here is what I would propose:
> "The IPG may be less than 12 Idles in length provided that the
> accumulated IPG Deficit Idle Count (DIC) does not exceed 3.  The DIC is
> computed at the end of each Inter Packet Gap as follows:
>     DIC = max( 0, DIC + 12 - IPG_length)
> This rule is necessary to allow SOP alignment of the output of the MAC
> in the case that packets are spaced by minimum Inter Packet Gaps.
> Without this rule, aligning an unaligned SOP following a minimum length
> IPG could only be effected by increasing the IPG length, and this would
> change the data rate.  Note also that the minimum IPG permitted by this
> rule is 9 bytes."
> The rule works by ensuring that no more than 3 Idles are stolen from the
> IPGs of any contiguous series of packets.  Note that the deficit could
> last an indefinite amount of time, so the concept of average can't
> really applied cleanly to defining IPG variation.
> Juan Pineda
> Bravida Corporation
> juan@xxxxxxxxxxxxxxx
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