Re: IDLEs on the SONET line
I would like to validate my understanding of the rates and terminology.
The STS-192c SPE uses the SDH VC-4-64c which has 260x64x9x64kb/s
total capacity or 9.584640 Gb/s. Now, I would view this as the virtual
"line rate"
of the mapping and the payload rate is
(64/66)*9.584640=9.294196.36363....Gb/s
is the virtual payload rate. That is, 9.29 is to 10 as 9.58 is to 12.5 --
the before and after
coding. I would thus be inclined to use the term "line line" with the number
9.58...Gb/s
What is the agreed upon use of terms?
Thank
Gary Nelson
Rich Taborek wrote:
> Tom,
>
> I don't understand your calculation. The result (10.016026 ns) seems to
> be the average LAN PHY IPG of 9.6 nsec divided by the WAN PHY data rate
> of 9.58464 Gbps.
>
> In my mind, the characteristics of idles to be put on the SONET line
> after stripping some for rate control is:
>
> a) an integer number of bytes;
> b) has a minimum dependent on the minimum specified for the WAN PHY
> primarily for clock rate compensation reasons and is typically dictated
> by coding requirements as is the case for the LAN PHY where the minimum
> transmitted IPG is 9 bytes and the minimum received IPG is 5 (???) bytes
> (note: clock rate compensation is differentiated from MAC to WAN PHY
> data rate compensation);
> c) given an average IPG of 12 bytes, has an average duration of
> 10.016026 nsec.
>
> Please tell me if I'm missing something.
>
> Best Regards,
> Rich
>
> --
>
> >Tom Alexander wrote:
> >
> >Vinitha,
> >
> >Assuming back-to-back packets, the average IPG that will be present
> >in the packet stream mapped to the SONET payload after deletion of
> >idles will be 9.6 nsec. In the WAN-PHY application, the MAC will
> >expand the IPG to lower the sustained data rate to < 9.58464 Gb/s while
> >keeping the instantaneous data rate at 10.000 Gb/s. Effectively, this
> >means that the minimum IPG will be increased to > 10.016026 nsec.
> >When the PCS/WIS combination causes the extra idles to be
> >deleted, this IPG will come back to 9.6 nsec.
> >
> >Regards,
> >- Tom Alexander
>
> >> Hi ALL,
> >>
> >> This is regarding the number of IDLEs to be put on the
> >> SONET line after stripping some for rate control.
> >>
> >> What is the minimum IPG that must be there after deletion of idles?
> >>
> >> Regards
> >>
> >> Vinitha S
> >> CoreEl Labs Pvt. Ltd
>
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--
Dr. Gary A. Nelson
Zynrgy Group Inc
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