Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index


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.