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RE: Clock Tolerance and WAN PHY




Correction to my previous reflector note.  

At 23:55 01/01/27 +0900, Osamu ISHIDA wrote:
> Instead, I recommend vendors to support one more MAC rate of 
> 9.61 Gb/s.  This will allow us to map 64/66-encoded LAN-PHY signals 
> into OPU2 by simply deleting the inter-frame Idles. 
> 
> (9.61 Gb/s = 9 953 280 kbit/s * 64/66 * 237/238)

The recommended MAC rate for the OTN should be 9.69 Gb/s.
(9.69 Gb/s = 9 953 280 kbit/s * 64/66 * 238/237)

Best Regards,
Osamu


At 23:55 01/01/27 +0900, Osamu ISHIDA wrote:
> Hi Gary, and All,
> 
> Here is the clock and its tolerance of the client signal for G.709 OTN 
> (Optical Transport Network) that will be approved by ITU-T (Feb 2001). 
> It does not support the direct mapping of 10.3 Gb/s LAN-PHY signal. 
> 
> a) it accepts OC-192c (9 953 280 kbit/s) format with approximately 
>    +/- 45 ppm clock tolerance (CBR10G asynchronous mapping into OPU2)
>    OPU2: Optical Channel Payload Unit 2 (OPU1 is for 2.5G, OPU3 is for 40G)
> 
> b) it accepts OC-192c (9 953 280 kbit/s) with +/- 20 ppm tolerance
>    (CBR10G bit-synchronous mapping into OPU2)
> 
> c) it accepts bit stream (approximately 9 995 276.962 kbit/s) with 
>    +/- 20 ppm tolerance  
>    (Mapping of non-specific client bit stream into OPU2)
> 
> The possible directions I see in the 802.3ae WAN-PHY are;
> 
> 1) no change.  
>    WAN-PHY signal with +/- 100 ppm tolerance will be accommodated into 
>    OTN by ELTE (i.e. by using SONET pointer manipulation mechanism).
> 
> 2) reduce the WAN-PHY clock tolerance to +/- 45ppm.
>    This will allow us to map the WAN-PHY signal into OPU2 directly if 
>    the OTN edge equipment supports asynchronous mapping (i.e. byte 
>    stuffing mechanism similar to that using the SONET H3 byte).  
> 
> 3) reduce the WAN-PHY clock tolerance to +/- 20ppm.
>    This will allow us to map the WAN-PHY signal into OPU2 directly 
>    even if the OTN edge equipment only supports bit-synchronous mapping 
>    (i.e. WAN-PHY clock is used in the OTN signal as well).
> 
> I have no preference in the above three directions since my own 
> interest is to have 9.29 Gb/s MAC rate from the LAN Equipment.  
> Instead, I recommend vendors to support one more MAC rate of 
> 9.61 Gb/s.  This will allow us to map 64/66-encoded LAN-PHY signals 
> into OPU2 by simply deleting the inter-frame Idles. 
> 
> (9.61 Gb/s = 9 953 280 kbit/s * 64/66 * 237/238)
> 
> Best Regards,
> Osamu

---------------------------------------
Osamu Ishida,ishida@exa.onlab.ntt.co.jp
NTT Network Innovation Laboratories
TEL:+81-468-59-3263 FAX:+81-468-55-1282
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