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  • To: "Rajesh L G (rajeshlg)" <rajeshlg@xxxxxxxxx>
  • From: Anil Mehta <anil.mehta@xxxxxxxxxxxx>
  • Date: Mon, 12 Mar 2018 10:25:08 -0700
  • Cc: Adrian Butter <adrian.butter@xxxxxxxxxxxxxxxxxxx>, "Mike Blair (mblair)" <mblair@xxxxxxxxx>, "fibre_channel@xxxxxxxxxxxxxxxxxxxx" <fibre_channel@xxxxxxxxxxxxxxxxxxxx>, "Abhinav Chander (achander)" <achander@xxxxxxxxx>, "Vasuki H A (avasuki)" <avasuki@xxxxxxxxx>
Do you have a proposal on what to add in the document?

Anil 

On Mon, Mar 12, 2018 at 12:59 AM, Rajesh L G (rajeshlg) <rajeshlg@xxxxxxxxx> wrote:

Hi Anil,

 

Thanks for the confirmation.

 

Would be good to have this documented lest somebody designs a receiver assuming 5.3.7.2 will not be violated.

 

Regards, Rajesh

 

From: Anil Mehta <anil.mehta@xxxxxxxxxxxx>
Date: Thursday, 8 March 2018 at 1:23 AM
To: "Rajesh L G (rajeshlg)" <rajeshlg@xxxxxxxxx>
Cc: Adrian Butter <adrian.butter@globalfoundries.com>, "Mike Blair (mblair)" <mblair@xxxxxxxxx>, "fibre_channel@standards.incits.org" <fibre_channel@standards.incits.org>, "Abhinav Chander (achander)" <achander@xxxxxxxxx>, "Vasuki H A (avasuki)" <avasuki@xxxxxxxxx>


Subject: Re: [fibre_channel] Thoughts on FC-FS-5 Open Comments Cisco-001 & Cisco-002

 

Hi Rajesh,

Adrian is out of office. So I thought I'll respond to this.

 

When an FC port is generating streams for transmission it should follow all the rules mentioned in all the sections e.g. preceding and following the primitive signal with two fill words.  Then AM logic can insert AM and delete fill words to compensate for it according to the AM insertion and fill word deletion  rules. 

 

If this approach is followed then to make room for AM, fill words would be deleted from the original  stream generated by the FC Port and 1 and 2 would be legal to see on the wire. 

 

Anil 

 

On Fri, Mar 2, 2018 at 3:46 AM, Rajesh L G (rajeshlg) <rajeshlg@xxxxxxxxx> wrote:

Hi Adrian,

 

Quoting the section relevant to my question:

“If an FC_Port transmitter is not repeating the Transmission Word stream of a receiver, the FC_Port shall

transmit at least six Primitive Signals between each EOF and the next SOF, unless Alignment Markers are

being inserted or rate adaptation requires Primitive Signal deletion. Of the six or more Primitive Signals

transmitted, at least four shall be Fill Words. If Alignment Marker insertion or rate adaptation require

deletion of Primitive Signals, then the FC_Port shall retain at least two Fill Words consecutively following

each EOF.”

 

This text seems to indicate that in streams that have alignment marker elsewhere, the following are legal.

  1. EOF-IDLE-IDLE-RRDY-SOF
  2. EOF-IDLE-IDLE-RRDY-IDLE-IDLE-RRDY-IDLE-SOF

 

But this violates the rules mentioned in other sections, viz.:

5.3.7.2

To assure a sufficient number of Fill Words between frames, the originator of any Primitive Signal other than Idle shall precede and follow the Primitive Signal by a minimum of two Fill Words.

 

Are the examples I gave above legal?

 

Regards, Rajesh

 

From: Adrian Butter <adrian.butter@globalfoundries.com>
Date: Wednesday, 28 February 2018 at 3:21 AM
To: "Rajesh L G (rajeshlg)" <
rajeshlg@xxxxxxxxx>
Cc: Anil Mehta <
anil.mehta@xxxxxxxxxxxx>, "Mike Blair (mblair)" <mblair@xxxxxxxxx>, "fibre_channel@standards.incits.org" <fibre_channel@standards.incits.org>, "Abhinav Chander (achander)" <achander@xxxxxxxxx>, "Vasuki H A (avasuki)" <avasuki@xxxxxxxxx>
Subject: Fwd: [fibre_channel] Thoughts on FC-FS-5 Open Comments Cisco-001 & Cisco-002

 

Hi Rajesh,

 

I think the relevant rules to mention in this regard are contained in 11.3.3:

=======================================================

11.3.3 Frame Transmission

Frame transmission shall be performed by inserting a frame immediately following a series of Fill Words

(see 11.3.2). Fill Words shall be transmitted immediately upon completion of the frame. A minimum of two

Fill Words shall be transmitted consecutively following the EOF of each frame transmitted by any FC_Port

transmitter.

If an FC_Port transmitter is repeating the Transmission Word stream of a receiver that is not capable of

exercising buffer-to-buffer flow control (e.g., L_Ports with REPEAT true), the transmitter may insert or

remove Fill Words from the Transmission Word stream in order to adjust for timing skew between the

receiver and transmitter; however, it shall retain at least two Fill Words consecutively following each EOF.

If an FC_Port transmitter is repeating the Transmission Word stream of a receiver that is capable of

exercising buffer-to-buffer flow control, the FC_Port shall transmit at least six Primitive Signals between

each EOF and the next SOF. Of the six or more Primitive Signals transmitted, at least four shall be Fill

Words.

If an FC_Port transmitter is not repeating the Transmission Word stream of a receiver, the FC_Port shall

transmit at least six Primitive Signals between each EOF and the next SOF, unless Alignment Markers are

being inserted or rate adaptation requires Primitive Signal deletion. Of the six or more Primitive Signals

transmitted, at least four shall be Fill Words. If Alignment Marker insertion or rate adaptation require

deletion of Primitive Signals, then the FC_Port shall retain at least two Fill Words consecutively following

each EOF.

See FC-AL-2 for Arbitrated Loop specific frame transmission requirements. See 11.3.9 for frame reception

requirements.

======================================================= 

Does that help address the question/concern?

 

Regards,

 

Adrian

---------- Forwarded message ----------
From: Rajesh L G (rajeshlg) <
rajeshlg@xxxxxxxxx>
Date: Tue, Feb 27, 2018 at 11:00 AM
Subject: Re: [fibre_channel] Thoughts on FC-FS-5 Open Comments Cisco-001 & Cisco-002
To: Anil Mehta <
anil.mehta@xxxxxxxxxxxx>, "Mike Blair (mblair)" <mblair@xxxxxxxxx>
Cc: Adrian Butter <
adrian.butter@globalfoundries.com>, "fibre_channel@standards.incits.org" <fibre_channel@standards.incits.org>, "Abhinav Chander (achander)" <achander@xxxxxxxxx>, "Vasuki H A (avasuki)" <avasuki@xxxxxxxxx>

Hi Anil, Adrian,

 

We have had some people interpreting that the 2 IDLE rule is applicable only for slower speeds. Hence seeking the clarification.

 

Depending on implementation, IDLEs may need to be deleted to make space for alignment marker. Say, if one IDLE each is deleted in 4 inter-packet gaps and this resulted in violating the 2 IDLE rule, is that compliant?

 

Regards, Rajesh

 

From: Anil Mehta <anil.mehta@xxxxxxxxxxxx>
Date: Tuesday, 27 February 2018 at 1:54 AM
To: "Mike Blair (mblair)" <
mblair@xxxxxxxxx>
Cc: Adrian Butter <
adrian.butter@globalfoundries.com>, "fibre_channel@standards.incits.org" <fibre_channel@standards.incits.org>, "Rajesh L G (rajeshlg)" <rajeshlg@xxxxxxxxx>, "Abhinav Chander (achander)" <achander@xxxxxxxxx>, "Vasuki H A (avasuki)" <avasuki@xxxxxxxxx>
Subject: Re: Fwd: [fibre_channel] Thoughts on FC-FS-5 Open Comments Cisco-001 & Cisco-002

 

That is correct. The 257 bit word takes the place of four 66 bit transmission words. So multiple idles need to be removed to make room for an alignment marker. 

 

I'm not sure why this leads to violating the 2 Fill word requirement. Can you elaborate on what requirement you are talking about and why you think it will be violated?

 

 

Anil 

 

On Mon, Feb 26, 2018 at 12:10 PM, Mike Blair <mblair@xxxxxxxxx> wrote:

Hi Adrian,Anil,
We had a discussion in Cisco today and the real question we are wondering on has not really been addressed (or at least I dont think so). Our question relates to the difference in the length of an idle (32 bits) and the alignment marker (257 bits). It is going to take the removal of many idles to "make room" for the insertion of a single alignment marker at the transmitter. This means that there are going to need to be a number of places that we violate the 2 fill words in order to find enough idles to remove such that a alignment marker can be inserted. A similar issue is on the receiver side.

I am adding to the email thread a few of our hardware folks to help with the discussion.

Thanks ... Mike

On Mon, 26 Feb 2018, Anil Mehta wrote:

Hi Adrian/Raul,I agree with your comments on this issue. For Cisco-001, I think we can just simply delete the following sentence:



The alignment marker has the form of a specially defined 66-bit block with a control transmission word
synchronization header.
Just continue the first paragraph in 5.5.3 with: These markers interrupt ....

For Cisco-002 I agree with what Adrian stated. Furthermore, we have been working on a proposal to allow the remote link partner to query what the parameters were set to when a degrade indication is received and take
administrative action to change them if desired.
Anil
On Fri, Feb 23, 2018 at 2:43 PM, Adrian Butter <
adrian.butter@globalfoundries.com> wrote:
      Hi Raul,
Thanks for the feedback on Cisco-001. And I do agree with your point about the AM format being a specially defined 257-bit pattern (rather than 66 bit). I hadn't
considered that when I reused the 802.3 Clause 82 text. I'll update the proposed text accordingly...

Thanks,

Adrian
---------- Forwarded message ----------
From: Mr. Raul Oteyza <
raul.oteyza@xxxxxxxxxx>
Date: Fri, Feb 23, 2018 at 4:52 PM
Subject: Re: Fwd: [fibre_channel] Thoughts on FC-FS-5 Open Comments Cisco-001 & Cisco-002
To:
fibre_channel@standards.incits.org


Hi Adrian,

My input for Cisco-001:

I agree with much of what you have written –
1.      That Alignment Markers can’t be considered Fill Words and can’t follow the transmission and reception requirements of Fill Words.
2.      A more apt description is that Alignment Markers replace Fill Words at the FC-1 transmitter, and conversely Fill Words replace Alignment Markers at the FC-1
receiver. Note that the manner in which this replacement occurs is vendor specific and therefore beyond the scope of the FC-FS-5 standard

The proposal for the added text for 64GFC, 128GFC, and 256GFC is spot on and appears clear and easy to understand.

The only part of the sentence that I disagree with is the first sentence that says “The alignment marker has the form of a specially defined 66-bit block with a control
transmission word
synchronization header.”
a.      Reason: The Alignment Marker has no relationship to a 66B formatted word nor does it have a synchronization header.  Its format is simply a 257-bit pattern
containing 2-bits of Remote Degrade values (one which is inverse to another), and a fixed data pattern.  This is true for 64GFC, 128GFC, and 256GFC.
b.      Proposal:
i.      Replace the sentence with
1.      The alignment marker has the form of a specially defined 257-bit pattern consisting of two Remote Degrade bits and a fixed data pattern.
2.      Or, The alignment marker has the form of a specially defined 257-bit pattern consisting of two Remote Degrade bits (one which is an inverse to another) and a fixed
data pattern.

Raul



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