are flow control and half-duplex support mandatory for gigabit Ethernet?

Hi all, I am developing a gigabit Ethernet MAC and I would like to know if in order to be compliant with the 802.3 standard I must support flow control and half duplex operation. I must also admit that I'm a bit confused as to which of the many 802.3 standards I must adhere to. To put it simply, I want my product to say "802.3XXXX" compliant, where XXXX can be anything :). Thanks! Yoav

Reply to
yoav
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If you read the standard itself, you will find that neither full-duplex operation nor flow control are mandatory. Of course, you must indicate which optional features are implemented on your PICS proforma (also part of the standard).

I cannot conceive of a device that can claim conformance to 802.3xxxx, where xxxx can be anything. Are you saying that you are building a universal networking device, that conforms to 802.3/4/5/11/16/etc.? Any practical device will be conformant (if at all) only to those sections of 802 that apply to such a device. As the designer, *you* are charged with knowing (or figuring out) which sections apply, and ensuring that your device is conformant, before making such claims.

-- Rich Seifert Networks and Communications Consulting 21885 Bear Creek Way (408) 395-5700 Los Gatos, CA 95033 (408) 228-0803 FAX

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Reply to
Rich Seifert

I think maybe Yoav was talking about potential 802.3a or 802.3something additions to the standard. But as far as I can tell, IEEE 802.3-2005 incorporates all of the past extensions.

In the spirit of his question, perhaps he's saying he wants to incorporate all of this fancy stuff. POE, link aggregation, flow control, 1 and 10 Gb/s, and whatever used to be described in separate documents before the 2005 version of the standard. It's still a tall order.

Bert

Reply to
Albert Manfredi

Dear Rich, Thanks a lot for your answer. What I meant by "XXX can be anything", was not that I want it to be compliant to ALL the XXX options, but just to one, and I am trying to understand which one it is. In other words, if I have a MAC with the following features:

  1. Supports only gigabit Ethernet (not 10/100)
  2. Does not support flow control
  3. Does not support half duplex operations. Can I say (assuming I comply to all other points in the standard) that I am compliant to 802.3ab, for example? am I compliant to 802.3 2002?

I apologize for my ignorance :)

Yoav.

that allows me to support the following: gigabit ethernet ONLY (not

10/100) to support flow control and half duplex and only support gigabit ethernet and not 10/100.

Rich Seifert wrote:

Reply to
yoav

Projects such as "802.3ab" (which, by the way, was the 1000BASE-T copper PHY, not the MAC or anything else) generally exist as standalone documents for only a short period of time. On a regular basis, we sweep all of these amendments into the base document, and the "802.3ab" standard ceases to exist. (In this particular case, it became Clause 40 of 802.3.)

You can rightfully claim conformance to 802.3 if you meet all of the normative requirements applicable to the product you are building. Most manufacturers don't bother to identify (at least not in the product marketing literature) which specific clauses or subclauses apply, unless it is a very specific product or the customers ask for such specificity. It is your job to read the standard carefully, however, to determine which normative requirements are applicable.

When there are options (e.g., half-duplex operation, flow control, etc.) it is useful to use the PICS (Protocol Implementation Conformance Statement) proforma to identify which features have been implemented. The PICS is also useful for identifying which portions of the standard comprise normative requirements; for those clauses drafted within the last 15 years or so, the standard always provides a PICS proforma that extracts all of the normative requirements and options into a single, handy location.

-- Rich Seifert Networks and Communications Consulting 21885 Bear Creek Way (408) 395-5700 Los Gatos, CA 95033 (408) 228-0803 FAX

Send replies to: usenet at richseifert dot com

Reply to
Rich Seifert

Yoav, The most recent base standard is IEEE Std 802.3-2005. Since then there have been a few additions. 802.3an-2006 and 802.3aq-2006 added extra 10 Gig PHYs but did not touch the MAC. 802.3as-2006 extended the max frame size to

2000 bytes which means you should probably add an option to your MAC to allow reception of frames of this size.

I don't think you can claim full MAC compliance to 802.3-2005 because that would imply half-duplex and 10/100 operation.

If you describe your MAC as gigabit full duplex only, then people will know what you mean and assume it is compliant to the relevant parts of the spec (how could it not be?). You will also have to specify your MAC's interfaces.

For gigabit Ethernet there is absolutely no need to support half-duplex operation.

Arthur.

Reply to
Marris

(snip)

I know for a long time 100baseTX items that I buy would mention 802.3u. Once it gets onto the package, it probably stays there even if it is moved into the base standard.

It is usual for gigabit NICs to support 10/100 operation. It is probably so common that one might not even read the box to check.

I can see that a special purpose device might not need backward compatibility. Still, I would be sure to carefully explain that only gigabit was supported.

Do 10/100/1000 NICs support half duplex gigabit as a side effect of support for half duplex 10/100? Or do they not support it at all?

-- glen

Reply to
glen herrmannsfeldt

No they don't. Half-duplex gigabit Ethernet significantly increases the slot-time making it different from 10/100. In increasing the slot-time it requires carrier extension to be added to minimum size frames to pad them out to the slot-time.

Reply to
Marris

Reply to
yoav

No; the PICS are specific to each clause. You pick your clause, you pick your PICS. It may drive you insane, but in 802.3 (as in life) "there is no Sanity Clause." (puns intended)

-- Rich Seifert Networks and Communications Consulting 21885 Bear Creek Way (408) 395-5700 Los Gatos, CA 95033 (408) 228-0803 FAX

Send replies to: usenet at richseifert dot com

Reply to
Rich Seifert

It is only later clauses that have PICS. Clause 4 which specifies the MAC does not have a PICS. However GMII does have a PICS. I think it is at the end of Clause 35.

Reply to
Marris

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