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Re: [802.3ae] Wan Interface Sublayer



Gary

This is a complex issue in a hypothetical case with worst case SONET
eye mask none of the existing CDR will function.  But well designed
SONET link
operate reliably without an issue, but there exist some pathological
scenario.

IEEE has specified jitter tolerance in term of DJ, RJ, and some SJ
reassembling
more like real life operation.  IEEE specification is more difficult on
the
CDR as the total jitter at the input of the CDR could be as high as
0.7-0.5 UI.

Beside the pathological scenario most long haul Sonet optics have
extremely 
low jitter on the transmit side.  However an IEEE complaint transmitter
may introduce more jitter especially deterministic and could break the 
SONET receiver.

Thanks,

Ali

Gary Nicholl wrote:
> 
> Roy,
> 
> One difference might be that OC-192c POS interfaces are fully compliant to
> SONET/SDH jitter specifications (in terms of generation, transfer and
> tolerance). The two parameters that are important with regard to interop
> with long haul DWDM systems are obviously jitter generation and jitter
> tolerance. If I understand correctly the 10GbE WAN PHY is not currently
> aligned with SONET/SDH jitter specs. Any thoughts about the impact of this
> on the interop with long haul systems ? I guess it was always my
> understanding that one of the functions of this mysterious ELTE was to
> convert from WAN PHY jitter specs to SONET/SDH jitter specs?
> 
> Gary Nicholl .............
> 
> At 10:29 AM 8/27/2001 -0500, Roy Bynum wrote:
> 
> >Mike,
> >
> >We are currently deploying OC192c POS over long haul systems using only
> >amplifiers and SREs.  The network management of the POS systems at each
> >end of the SONET span is separate from the SONET span.  The POS systems
> >are "free-running" relative to SONET synchronization.  Fault protection is
> >being handled by the SREs.  I do not see any difference in deploying 10GbE
> >WAN PHY in the same way.
> >
> >Thank you,
> >Roy Bynum
> >
> >At 04:56 PM 8/24/01 -0500, Ayers, Mike wrote:
> >
> >
> >> > From: Roy Bynum [mailto:rabynum@xxxxxxxxxxxxxx]
> >> > Sent: Friday, August 24, 2001 01:09 PM
> >>
> >> > Being a SONET transmission service provider with OC192 SREs
> >> > already in the
> >> > transmission network.  With the WAN PHY at +/-20PPM, your
> >> > possibility #1 is
> >> > correct.  The SONET SREs (read SONET class B regenerators)
> >> > can handle the
> >> > WAN PHY and provide section level performance monitoring and
> >> > protection.
> >>
> >>
> >>
> >> > From: James Colin [mailto:james_colin_i@xxxxxxxxx]
> >> > Sent: Friday, August 24, 2001 12:14 AM
> >>
> >> > Option (4) is the correct answer. SONET and WIS must
> >> > stay on their own network. A network device called
> >> > "ELTE" is doing the bridging between the WIS net and
> >> > the SONET.
> >>
> >>
> >>         Hmmm - I think a little more discussion on this is in order, and by
> >>minds greater than mine.  My interest is this:  if it is possible to route
> >>WIS directly over a SONET network, then the management model for WIS becomes
> >>much more involved, since it must support management by either the SONET
> >>model or the traditional ethernet model (two very different models).
> >>However, if an ELTE is required betrween the two, it effectively separates
> >>the networks such that there is no overlap nor need for two management
> >>models; ethernet being used on one side of the ELTE and SONET on the other.
> >>It does not matter, from my perspective, whether an ELTE gets used - what
> >>matters is whether the ELTE is required.  Is it possible that the SRE is
> >>acting as an ELTE in Roy's scenario?
> >>
> >>
> >>         Thanks,
> >>
> >>/|/|ike
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