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Re: HARI: Question regarding byte (column?) versus word striping

I am getting somewhat confused on this isse. Could someone give a pointer
to where the
concept of "lane", "column" and "striping" are detailed ?


At 08:06 PM 1/6/00 -0800, you wrote:
>I believe you are missing the point of how word striping works.
>As the number of lanes scales up, word striped data still uses
>ONLY ONE WORD to be added/deleted for clock tolerance compensation.  
>That is, for n lanes, byte striping must delete n characters (ie, 
>a column) while word striping must delete only 4 characters (ie,
>a word) from any one of the n lanes.  
>Without the constraint that the packet begin in a particular lane,
>I believe that the IPG is CONSTANT for word striping, but must
>grow linearly with the number of lanes for byte striping.
> [Please note that the number of bytes (characters) in a "word"
> in word striping is chosen to span the expected skew, yielding
> its great simplicity of implementation.  For HARI, it is merely 
> coincidence that the word size is the same as the number of lanes.
> The word size and the number of lanes are independent things.]
>I appreciate your comments on this issue, and I agree completely.
>Please let me know if I've missed anything above, or if I need to 
>improve on my explanation.
>Rich Taborek wrote:
>> Simon,
>     (text deleted)
>> When Hari is scaled to higher speeds, Column-Striping can function with a
>> smaller IPG than can Word-Striping. Two requirements of the IPG are:
>> 1) Link synchronization - commas required
>> 2) Clock tolerance compensation - insert/remove protocol required
>> Column-Striping requires only a single column of commas (K) for link
>> synchronization and utilizes a single column of skips (R) for clock
>> compensation. The minimum IPG size based on starting a new packet in
lane 0 is
>> 3n, where n=number of lanes. That's one n for the K column, another for
the R
>> column and a third possibly complete column containing the End-of-Packet
>> delimiter plus pad characters.
>> Word-Striping uses words containing commas which may be inserted/deleted
>> the IPG. The minimum IPG size is 5n, where n=number of lanes. That's 4n
for 4
>> deletable Idles and one more word containing the End-of-Packet delimiter
>> pad characters.
>> Best Regards,
>> Rich
> Mike Jenkins               Phone: 408.433.7901            _____     
> LSI Logic Corp, ms/G715      Fax: 408.433.7461        LSI|LOGIC| (R)   
> 1525 McCarthy Blvd.       mailto:Jenkins@xxxxxxxx        |     |     
> Milpitas, CA  95035      |_____|    
Best Regards,

Devendra Tripathi
XaQti Corporation
3100 De La Cruz Boulevard
Santa Clara, CA  95054
Phone: (408) 986-4380 Ext 103
Fax:	(408) 986-6050
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