Re: [STDS-802-3-EPOC] [802.3_EPOC] MMP implementation issues: Multiple FCUs and MMP, is it different?
Duane,
I am making here a far reaching assumption that an operator is educated
enough not to setup services in excess of what they can actually provide
with the given CNU. I hope it is not too far fetched. Otherwise, we'll be
asking physicl layer to correct configuration errors of the service layer.
Marek
On 9 January 2013 17:20, Duane Remein <Duane.Remein@xxxxxxxxxx> wrote:
> Marek,****
>
> Only if you also assume the FCU has infinite buffers J****
>
> Best Regards,****
>
> Duane****
>
> ** **
>
> FutureWei Technologies Inc.****
>
> duane.remein@xxxxxxxxxx****
>
> Director, Access R&D****
>
> 919 418 4741****
>
> Raleigh, NC****
>
> ** **
>
> *From:* Marek Hajduczenia [mailto:marek.hajduczenia@xxxxxxxxx]
> *Sent:* Wednesday, January 09, 2013 10:06 AM
>
> *To:* STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
> *Subject:* Re: [STDS-802-3-EPOC] [802.3_EPOC] MMP implementation issues:
> Multiple FCUs and MMP, is it different?****
>
> ** **
>
> Andrea, ****
>
> ** **
>
> If we assume that FCU can do the traffic shaping, OLT does not need any
> shalls at all … ****
>
> ** **
>
> Marek****
>
> ** **
>
> *From:* Garavaglia, Andrea [mailto:andreag@xxxxxxxxxxxxxxxx]
> *Sent:* Wednesday, January 09, 2013 15:04
> *To:* STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
> *Subject:* Re: [STDS-802-3-EPOC] [802.3_EPOC] MMP implementation issues:
> Multiple FCUs and MMP, is it different?****
>
> ** **
>
> Hi Ed, all,****
>
> I still see one point that seems to me not fully clarified, talking about
> *SMP* (simplest case) and a deployment like the one shown in the figure.**
> **
>
> ** **
>
> Let me try to make an example, and see how this is supposed to work, for
> my understanding:****
>
> **- **EPON is 10 Gb/s and serves 3 FCUs and 2 ONUs****
>
> **- **Each ONU is compliant to 802.3av and can handle 10 Gb/s
> speed****
>
> **- **The FCU has an optical side also compatible with 802.3av,
> but cannot handle on the coax side 10 Gb/s – I think this is reasonable
> assumption****
>
> **o **Let’s assume the following for FCUs, on coax (other example won’t
> change the problem): FCU-1 runs at 2 Gb/s, FCU-2 runs at 1 Gb/s, FCU-3 runs
> at 1.5 Gb/s****
>
> **o **In each coax branch we use SMP as stated below, so CNUA, A’, etc.
> can handle a link from FCU -> CNU of 2 Gb/s, CNU B, B’, etc. handles 1 Gb/s
> and CNU C, C’, etc. handle 1.5 Gb/s****
>
> **- **In my opinion the OLT * shall not*:****
>
> **o **Exceed 10 Gb/s delivery to any ONU – this is already guaranteed
> as being the upper limit of the EPON optical system****
>
> **o **Exceed 2 Gb/s aggregated traffic to FCU-1 – this is not
> guaranteed by EPON line rate alone****
>
> **o **Exceed 1 Gb/s aggregated traffic to FCU-2 – this is not
> guaranteed by EPON line rate alone****
>
> **o **Exceed 1.5 Gb/s aggregated traffic to FCU-3 – this is not
> guaranteed by EPON line rate alone****
>
> ** **
>
> It seems to me that the OLT needs to shape traffic for each FCU according
> to the rules above, otherwise some of the FCU coax part will be overloaded
> - so it seems to me the OLT needs to shape traffic to each FCU and this is
> regardless the FCU particular architecture. ****
>
> I assume the OLT shall and can do that - can be confirmed the OLT is able
> to do that?****
>
> ** **
>
> Thanks,****
>
> Andrea****
>
> ** **
>
> *From:* Ed (Edward) Boyd [mailto:ed.boyd@xxxxxxxxxxxx<ed.boyd@xxxxxxxxxxxx>]
>
> *Sent:* Tuesday, January 08, 2013 19:59
> *To:* STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
> *Subject:* Re: [802.3_EPOC] MMP implementation issues: Multiple FCUs and
> MMP, is it different?****
>
> ** **
>
> Matt,****
>
> ** **
>
> Thanks for the reply. It doesn’t change anything. You can say that A+B+C
> is more than 10Gbps but you won’t be able to fully utilize the coax
> networks. The key point is that the shaping rate for sub-network (A, B, C)
> is a solid limit for each network. This is fairly easy to do with a switch.
> ****
>
> ** **
>
> The shaping equation is very different if MMP is allowed on the network.
> What is my bandwidth limit for network A if it has a mixture of modem
> types? I set the shaping rate based on 1024QAM or 4096QAM? I assume that
> you limit it to 4096QAM and decrement more credits if it is to a 1024QAM
> destination. Jorge’s drawing suggest that we have a limit for 1024QAM
> modems across all networks A, B, and C. That doesn’t prevent congestion
> on any one network. The shaping needs to be smarter than that. It would
> need to hierarchical (independent for A, B, and C) and it would need to
> take into account the MMP data rate for each CNU on the network. The more
> complicated decision is the FEC overhead from a short termination. How
> does the RS layer know when the PHY is going to insert a shortened last
> code word? I think that you would need to go back to the packet FEC that
> was used in 802.3ah. ****
>
> ** **
>
> The rate control is very simple for the RS layer in the current plan. We
> insert idles for a fixed FEC overhead for a fixed data rate pipe. It is
> programmed value based on the PHY Link up result. When you talk about MMP,
> I need to insert idles based on the spectrum configured, per-LLID/MMP
> modulation order, and insert idles based on the shortened FEC termination.
> The idles to insert for FEC is based on whether the packet is in the same
> FEC block on the same coax network. This is very complicated function and
> not available on any OLT. Jorge’s drawing is not accurate for that
> reason. There is not OLT that can perform this function. Additionally, I
> think that it is very complicated or impossible for the RS to come up with
> this function for the FEC. It would need to be aware of the sub-networks
> and align its short FEC terminations with the PHY.****
>
> ** **
>
> Thanks,****
>
> Ed…****
>
> ** **
>
> ** **
>
> *From:* Matthew Schmitt [mailto:m.schmitt@xxxxxxxxxxxxx<m.schmitt@xxxxxxxxxxxxx>]
>
> *Sent:* Tuesday, January 08, 2013 9:13 AM
> *To:* Ed (Edward) Boyd; STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
> *Subject:* Re: [802.3_EPOC] MMP implementation issues: Multiple FCUs and
> MMP, is it different?****
>
> ** **
>
> Ed,****
>
> ** **
>
> Thanks much for putting this out there, as it helps illustrate where we
> may be making different assumptions.****
>
> ** **
>
> For me, I was * not* assuming that the sum of A+B+C is less than or equal
> to 10 Gbps; on the contrary, I've been assuming that the total available
> bandwidth for the sum of the FCUs would likely be greater than 10 Gbps.***
> *
>
> ** **
>
> If you change that assumption, does that change your conclusion about the
> difference between multiple FCUs and MMP?****
>
> ** **
>
> Thanks!****
>
> ** **
>
> Matt****
>
> ** **
>
> *From: *"Ed Boyd (Edward)" <ed.boyd@xxxxxxxxxxxx>
> *Reply-To: *"Ed (Edward) Boyd" <ed.boyd@xxxxxxxxxxxx>
> *Date: *Monday, January 7, 2013 5:32 PM
> *To: *"STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx" <
> STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>
> *Subject: *[802.3_EPOC] MMP implementation issues: Multiple FCUs and MMP,
> is it different?****
>
> ** **
>
> Jorge, Duane, and all,****
>
> ****
>
> I started a new thread since I wasn’t quite sure where to insert my
> reply. Let me start with the drawing with multiple FCUs question that you
> proposed. ****
>
> ****
>
> [image: Description: cid:image001.jpg@01CDECF9.0BFEEB40]****
>
> ****
>
> The assumption with multiple FCUs is that you are shaping 3 pipes (A, B, &
> C) inside the 10G EPON downstream. If you make that sum of those 3 less
> than the maximum rate, you can send them down the PON at the same with a
> single packet of jitter. The total bandwidth of the downstream is a
> constant since it is the sum of the 3 constants.****
>
> ****
>
> For Multiple sub-pipes: Total BW = A + B + C (Sum of 3 Constants)****
>
> ****
>
> In the case of MMP, you have a single pipe with a changing data rate based
> on the destination. The data rate from the OLT is not a constant or the
> sum of 3 pipes. It is going up and down based on the destination. A
> single shaping bucket is used but the debit for the reverse leaky bucket is
> different based on destination. The total bandwidth equation is an OR.***
> *
>
> ****
>
> For MMP: Total BW = A | B | C. (The total bandwidth or maximum bandwidth
> is based on the traffic) ****
>
> ****
>
> ****
>
> I hope that helps. I will send a separate email on the other issues
> related to the MAC layer solution.****
>
> ****
>
> Thanks,****
>
> Ed…****
>
> ****
>
> [image: Description: Description: Description: Description: Description:
> Description: Description: Description: Description: Description:
> Description: Description: cid:image009.jpg@01CD505E.7B800DB0]****
>
> ****
>
> Edward Boyd | Sr Technical Director
> Broadcom Corporation | (O) 707-792-9008 | (M) 707-478-1146****
>
> ****
>
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