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Re: 20 ppm clock tolerance for WIS

Hi Gary,

At 4:33 PM -0400 00.5.31, Gary Nicholl wrote:
> Bottom line is that you bring up a good point to which I don't have a 
> good  answer.  I guess I will just open it up to the rest of the group 
> for discussion.

As a Carrier guy, I would like to put some comments on your Ottawa proposal;

In summary, 
(1) I agree that your SONET(-compliant) PHY will have market.
(2) I am not yet convinced why 802.3ae should define 'SONET-grade' OAM&P.
(3) We can use B1 (or B3) as performance monitor for the BER up to 10^-5.

(1) SONET(-compliant) PHY will have market

Assuming that adopting the SONET jitter spec for WIS, your proposal is 
not only 'SONET-compatible' but also 'SONET-compliant'.  It would work 
well in our installed base SONET/WDM infrastructure as your POS 
interfaces have done today.  As for the SONET jitter spec, we will pay 
some premium in 'SONET-grade' PMD when we need to connect it to the 
installed base SONET equipment; this is quite similar what Bruce Tolley 
has pointed out in the recent PMD discussions;

At 2:58 PM -0700 00.5.30, Bruce Tolley wrote:
> There is no threshold of pain in regard to cost, since if I cannot sell to 

(2) Do we need 'SONET-grade' OAM&P in 802.3ae?

In my sense, your proposal to add B2/K1/K2/M1 bytes is not the 'minimal 
SUBSET of SONET functionality' but 'ordinary SET of SONET functionality'.  
Your proposal has already satisfied the ITU-T Recommendation G707 that 
has defined the reduced SOH functionalities interface (Table6/G707).  
It sounds like 'SONET-grade' OAM&P to me.

As I understand, WAN-PHY proposal shown in the David Martin's presentation 
at Albuquerque ('Why WAN-PHY?') can be now interpreted as follows;

(A) need mechanism that slowing the MAC rate to 9.29 Gb/s
(B) define WIS accommodating 64/66 PCS output into SONET payload
(C) avoid 'SONET compliant' management, jitter, and systems.
    define minimal OAM&P functionality for WAN access/dark fiber.

With this minimal WAN-PHY definition alone, we can enjoy inexpensive jumper 
access to SONET/WDM infrastructure via ELTE that would be tolerable to LAN 
grade optics & jitter specifications.  ELTE in SONET domain will provide 
the SONET-grade OAM&P using B2 & K1/K2.

In this sense, I am not convinced yet why 802.3ae should define 'SONET-
compliant' PHY.  Please be sure that I am not saying we won't buy the 
'SONET-compliant' PHY; just wondering why minimal WAN-PHY would not be 
enough for the 802.3ae standard.  If you want, you can freely implement 
any additional SONET(-compliant) function as you like.  It had better be 
vender specific.   Basically SONET K1/K2 protection is very hard to 
assure interoperability since it requires fast negotiation between the 
link partners; we have to solve precise timing issues especially when we 
run into the dual-fault conditions.  This is why SONET is often referred 
to be non-interoperable between the different vendors......

I think 802.3ae had better be stuck with minimal OAM&P functionality 
that provides simple state-reporting mechanism such as J0, B1, and G1; 
these are all free from destroying interoperability.

(3) Performance Monitoring by B1

In your presentation slides#8, you have said that B1 (Bit Interleaved 
Parity 8) is not useful for performance monitoring.  This is not true to 
me; in OC192, B1 can be used to monitor the BER up to 10^-5 by using simple 
compensation curve.  Yes, we CAN distinguish between BERs higher than 10^-7. 
In detail please refer to Figure 2 in 

Y. Yamabayshi et al. 'High-speed regenerator section terminating LSIs'
Electronics Letters, 11th Nov. 1993 Vol.29, No.23. pp. 2057-2058

Also I would like to point out that ITU-T Recommendation G.783 has defined 
the performance monitoring (Signal Degrade) threshold at 10^-5 to 10^-9.  
Therefore I think we do not necessarily require B2 at least at 10Gb/s.

Best Regards,

At 4:33 PM -0400 00.5.31, Gary Nicholl wrote:
> At 06:56 PM 5/30/00 , Praveen Kumar wrote:
>>You recommend using "LAN PHY jitter specs".  This makes the WIS 
>>incompatible with installed base SONET . This doesn't seem to meet your 
>>goal of being compatible with installed OC-192 SONET 
>>infrastructure.  Please clarify.
> A good point. This probably does require some clarification. I guess 
> using the word 'recommend' might have been too strong because this is 
> an area which I believe still requires some further discussion.  
> Personally I would agree with you in that the only way to ensure 
> compatibility with the installed SONET based transport infrastructure 
> would be to use SONET jitter specs. This is the same conclusion we 
> came to about 12-18 months ago in the OIF  when we went down a similar 
> path of investigating relaxed jitter specs for Packet-Over-SONET  
> (POS) interfaces in order to lower cost. At the time this was 
> strongly opposed by both network operators and equipments suppliers. 
> If I remember correctly companies like British Telecom, AT&T, Marconni, 
> Lucent and Nortel were the most vocal in opposing any changes to the 
> jitter specifications.
> However there are some other points we need to consider here. Unlike 
> the issues of clock tolerance and overhead there probably is a 
> significant cost associated with meeting SONET jitter specs (or so I 
> have been told by a number of transceiver vendors).  I also believe 
> there is a strong desire within the group to use the same PMDs 
> (optics) for both the LAN and WAN phys, so therefore burdening the PMD 
> with meeting SONET jitter specs might add a lot of unnecessary cost and 
> complexity to the LAN application.
> Bottom line is that you bring up a good point to which I don't have a 
> good  answer.  I guess I will just open it up to the rest of the group 
> for discussion.

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