RE: [EFM] Split Ratios
I think I would agree. The main issue might be if the split ratio started
to approach a high number - then the MAC design might call for some
additional complexity - for example the split ratio design point for PCN
was 1:4000. At 1:4000 split ratios things like contention and containment
of broadcast domains become much more significant issues.
J
At 02:25 PM 7/21/01 -0700, Faye Ly wrote:
>It seems to me, split ratio should not be a gauging factor for
>EPON standardization? We can easily that split ratio such as
>1 to 16/32/128 ... would affect the bandwidth allocation scheme
>and whatever the BAS we choose to use, should take multiple
>split ratio (1/16, 1/32 ...) into consideration. We are pretty
>much done. I think the issue here is more on how the BAS is
>done to satisfy multiple split ratio requirements but not determine
>one a single split ratio.
>
>Your thoughts?
>
>-faye
>
>
>-----Original Message-----
>From: "Prat Gomà, Josep J." [mailto:jprat@xxxxxxxxxx]
>Sent: Friday, July 20, 2001 6:39 AM
>To: ketan.gadkari@xxxxxxxxxxxx
>Cc: stds-802-3-efm@ieee.org
>Subject: RE: [EFM] Split Ratios
>
>
>
>
>Selecting the split ratio is an easy way to provission different
>Guarantied
>Bandwidths (125, 62, 31 MBit/s...) to the users. A more fine-degree of
>split
>ratio than the standard ones (8,16,..) may be of interest in this terms
>(not
>in the power budget). With a convenient fiber/cable management this can
>also
>be easily re-configured, then making DBA perhaps redundant at the PON?.
>
>
>The concept of making use of the unsued bandwidth (above the guarantied
>bandwith) could be differentiated from the traffic priorisation of DBA,
>in
>my personal opinion.
>
>Josep
>UPC
>
>-----Mensaje original-----
>De: ketan.gadkari@xxxxxxxxxxxx [mailto:ketan.gadkari@xxxxxxxxxxxx]
>Enviado el: 19 July 2001 22:13
>Para: mike.obrien@xxxxxxxxxxxx; david.m.horne@xxxxxxxxx
>CC: stds-802-3-efm@ieee.org
>Asunto: [EFM] Split Ratios
>
>
>
>It is eaiser to manufacture a 1x8, 1x16, 1x32 etc because every split in
>the
>tree is an even split. (i.e. 50/50). If we had to make a 1x10, then
>some
>of the splits would have to be uneven i.e. 60/40 or 70/30. While this
>is
>possible and there are 1x10 and 1x12 splitters available they are non
>standard.
>
>Ketan Gadkari
>Alloptic Inc.
>
>-----Original Message-----
>From: mike.obrien@xxxxxxxxxxxx [mailto:mike.obrien@xxxxxxxxxxxx]
>Sent: Thursday, July 19, 2001 10:24 AM
>To: david.m.horne@xxxxxxxxx
>Cc: stds-802-3-efm@ieee.org
>Subject: RE: [EFM] RE: EPON TDMA
>
>
>
>Hi David,
> The split ratio's are powers of two because the splitters are
>made
>by cascading 1x2 (actually 2x2) splitters.
>
>-----Original Message-----
>From: Horne, David M [mailto:david.m.horne@xxxxxxxxx]
>Sent: Wednesday, July 18, 2001 9:03 PM
>To: 'Roy Bynum'; glen.kramer@xxxxxxxxxxxx
>Cc: stds-802-3-efm@ieee.org
>Subject: RE: [EFM] RE: EPON TDMA
>
>
>
>Where did the often-cited split ratios of 16 and 32 come from, anyway?
>It
>seems an argument can be made for holding off on finalizing the split
>ratio
>choice until the TDMA scheme is better defined and quantified. That way,
>it
>can be better matched (disaggregated and reaggregated) to Ethernet pipes
>on
>the ends of the EFM segment, and be easier to hand off to multiple
>service
>providers in a PoP. End-to-end Ethernet is the goal, after all.
>
>For example, a split ratio of 8 may be a better match for 100Mbps
>dedicated
>(logical) connections, once the actual TDMA overhead and guard bands are
>known. Compared to 16:1, the cost of the extra feeder fiber (cost of 2
>fibers split across 16 subs rather than 1 fiber split across 16) may be
>offset by the more compatible handoff logistics. For long drop fibers,
>with
>two 8:1's, the drops will be relatively shorter than a single 16-way
>split
>to the same endpoints. This may even offset the extra feeder fiber. But,
>there's no reason to stick with powers of 8 (that I can think of off
>hand)
>unless they make something easier. Maybe 10 or 12 or... are attractive
>after
>more details are agreed to.