RE: A Question about "Inter Packet Gap and SOP Lane alignment"
Hi,
So, what is the status.
Are we working according to
http://grouper.ieee.org/groups/802/3/ae/public/jul00/taborek_2_0700.pdf page
14 last line:
(An IPG of /A/, /K/, /R/ and then randomized /A/ spacing and /K/, /R/)
Or according to
http://grouper.ieee.org/groups/802/3/ae/public/jul00/taborek_1_0700.pdf
(An IPG with random selection between /A/ and /K/, /R/, and then randomized
/A/ spacing and /K/, /R/)
Did the committee decided about it?
And:
What about doing random selection between /A/ and /K/ for the first column,
then /R/, and then, if there exists a 3'rd column, substitute the /A/ or
/K/ (The one that did not occur in the first column).
Thx., and besr regards
Boaz
> -----Original Message-----
> From: Brown, Ben [BAY:NHBED:DS48] [mailto:bebrown@xxxxxxxxxxxxxxx]
> Sent: Monday, July 17, 2000 7:22 PM
> To: 802.3ae
> Subject: Re: A Question about "Inter Packet Gap and SOP Lane
> alignment"
>
>
>
>
> Boaz,
>
> Turning on your receiver in the middle of a packet stream
> is an unlikely situation. When your receiver is disabled,
> your transmitter is either disabled or reporting break link
> (somehow). This should tell your link partner (remember,
> these are all point-to-point links) to stop sending data
> because there's no one on this end to receive it. In this
> manner, when your receiver turns on, it should be receiving
> nothing but IDLEs meaning it has time to gain sync before
> it starts getting packets. Once it starts getting packets,
> the requirement for frequent /A/s and /K/s is gone and the
> occasional columns are sufficient to make sure lane alignment
> and deskew are still okay.
>
> If your link partner is sending data in light of your
> reporting break link, all bets are off.
>
> In order to satisfy the 12-byte average minimum IPG, some
> IPGs will be as short as 9 bytes while others may be as
> long as 15 bytes (see Steve Haddock's presentation):
>
> http://grouper.ieee.org/groups/802/3/ae/public/jul00/haddock_1
> _0700.pdf
>
> The longer IPGs are the ones Rich is referring to. Also,
> not all links are 100% utilized so there will be cases when
> there are no packets to send and longer IPGs will exist.
>
> Regards,
> Ben
>
> Boaz Shahar wrote:
> >
> > Ben and Rich,
> > Thank you for the explanations. However, there are some
> things which I'm not
> > so sure about:
> >
> > 1.Refering the state diagram at the end, after
> transmitting /A/ or /K/ and
> > /R/ columns, we randomize the distance to the next A (Which
> is uniformly
> > distributed between 16 to 31).
> >
> > Now, if it happened to be /K/, /R/ columns, then the next
> /A/ could be a
> > distance of 16 columns away (Or may never come, if a new
> packet starts
> > before). And, on the contrary, if it was /A/, /R/ and the
> next packet starts
> > immediately, then the next /K/ can be far away. Since the
> synchronization
> > condition requires 3x/K/ per lane and then /A/ for de
> skewing, due to this
> > randomization, if you turn on your receiver at the
> "middle", you don't know
> > when you will be synchronized! Actually, your time for
> synchronization is a
> > random variable.
> >
> > I think this is a disadvantage relative to the previous
> proposed /A/, /K/,
> > /R/ minimal sequence. Here, you can bound the time for
> synchronization,
> > avoiding the "Random Time" parameter.
> >
> > At least, if we MUST support this 12 bytes, I would suggest
> that the third
> > column will always be "the other one", i.e. if the first is
> /A/, and there
> > is a third column, it will always be /K/. And if the first
> is /K/, let the
> > third always be /A/, and only then start the randomization process.
> >
> > In addition, I saw that Rich mentioned again the minimal
> gap of /A/,/K/,/R/,
> > so it still an option? (The MIN IPG is 12 to 16 in this
> case, instead of 9
> > to 12, and the "time to sync" is deterministic.)
> >
> > Boaz
> >
> > > -----Original Message-----
> > > From: Brown, Ben [BAY:NHBED:DS48] [mailto:bebrown@xxxxxxxxxxxxxxx]
> > > Sent: Sunday, July 16, 2000 10:15 PM
> > > To: 802.3ae
> > > Subject: Re: A Question about "Inter Packet Gap and SOP Lane
> > > alignment"
> > >
> > >
> > >
> > >
> > > Rich,
> > >
> > > Allow me to clean up a few editing errors to avoid confusion:
> > >
> > > Rich Taborek wrote:
> > > >
> > > > 1) No change to EOP column which contains the first 1 to 4
> > > columns of the IPG.
> > > > Note that the EOP counts towards IPG.
> > >
> > > The EOP column contians the first 1 to 4 BYTES of the IPG.
> > >
> > > > 2) Transmit /A/ or /R/ randomly while maintaining minimum
> > > 16 column /A/ spacing.
> > >
> > > Transmit /A/ or /K/ randomly.
> > >
> > > Enjoy,
> > > Ben
> > >
> > > Rich Taborek wrote:
> > > >
> > > > Boaz,
> > > >
> > > > Your question is answered in a presentation made at the La
> > > Jolla meeting:
> > > > "8B/10B Idle Pattern for 12-byte IPG" by
> > > > Rich Taborek and Don Alderrou of nSerial,
> > > >
> > > http://grouper.ieee.org/groups/802/3/ae/public/jul00/taborek_1
> > > _0700.pdf
> > > >
> > > > This proposal modifies the fixed starting /A/K/R/ Idle
> > > pattern for all
> > > > applications of 8B/10B encoded 4-lane streams was accepted
> > > into the set of
> > > > baseline proposals along with the core XAUI/XGXS proposal.
> > > The specific change
> > > > is as follows:
> > > >
> > > > 1) No change to EOP column which contains the first 1 to 4
> > > columns of the IPG.
> > > > Note that the EOP counts towards IPG.
> > > > 2) Transmit /A/ or /R/ randomly while maintaining minimum
> > > 16 column /A/ spacing.
> > > > 3) Transmit /R/
> > > > 4) Transmit /K/, /R/ or /A/ randomly while maintaining
> > > minimum 16 column /A/
> > > > spacing until SOP detected.
> > > >
> > > > Note that this proposal works for IPGs as small as 9.
> > > Detailed state machines
> > > > are included at the end of the PDF file.
> > > >
> > > > Best Regards,
> > > > Rich
> > > >
> > > > --
> > > >
> > > > Boaz Shahar wrote:
> > > > >
> > > > > Hello Steve,
> > > > > I have a question in regards to your presentation "Inter
> > > Packet Gap..." in
> > > > > the last meeting:
> > > > >
> > > > > You suggest to use only 2 columns of Idle as a minimum
> > > for IPG. In previous
> > > > > proposals (e.g.
> > > > >
> > > http://grouper.ieee.org/groups/802/3/ae/public/may00/taborek_2
> > > _0500.pdf
> > > > > slide 14) the suggested gap is a minimum of 3
> > > columns-/A/, /K/, and /R/. So:
> > > > > Can you please say which of them should be eliminated, or
> > > define a procedure
> > > > > which say which type of Idle columns should be inserted?
> > > > >
> > > > > Thanks,
> > > > > Boaz
> > > >
> > > > -------------------------------------------------------
> > > > Richard Taborek Sr. Phone: 408-845-6102
> > > > Chief Technology Officer Cell: 408-832-3957
> > > > nSerial Corporation Fax: 408-845-6114
> > > > 2500-5 Augustine Dr. mailto:rtaborek@xxxxxxxxxxx
> > > > Santa Clara, CA 95054 http://www.nSerial.com
> > >
> > >
> > > --
> > > -----------------------------------------
> > > Benjamin Brown
> > > Router Products Division
> > > Nortel Networks
> > > 1 Bedford Farms,
> > > Kilton Road
> > > Bedford, NH 03110
> > > 603-629-3027 - Work
> > > 603-624-4382 - Fax
> > > 603-798-4115 - Home
> > > bebrown@xxxxxxxxxxxxxxxxxx
> > > -----------------------------------------
> > >
>
>
> --
> -----------------------------------------
> Benjamin Brown
> Router Products Division
> Nortel Networks
> 1 Bedford Farms,
> Kilton Road
> Bedford, NH 03110
> 603-629-3027 - Work
> 603-624-4382 - Fax
> 603-798-4115 - Home
> bebrown@xxxxxxxxxxxxxxxxxx
> -----------------------------------------
>