Mikael, PON versus Active Ethernet versus $topology_of_the_day makes no real difference. If you buy low port density shelves then your cost per port will be higher. BCP38 (and BCP64) have nothing to do with who is doing layer 2 since neither of those technologies pay any attention to the layer 2 network anyway. I'd be curious to see your reasoning as to why it needs to be done between layer 2 and layer 3 given that all of the access gear, including the Ethernet equipment, has layer 2 enforcement of layer 3 information like DHCP and static assignments of IP addresses. "It's cleaner just to do L1 and aggregate thousands or tens of thousands of residential properties in the same place." In my experience that's simply untrue today. Trying to put multiple operator's layer 2 gear into the collocation space needed inevitably leads to that space not having enough power, rack units, or cooling and that's not considering the complaints (actual) of ISP1 accusing ISP2's tech of intentionally "tripping" over a cable and causing an outage for them. Keep in mind that in most places a muni network is currently feasible that muni doesn't have a telco quality wiring center in place already and where cities have the resources to build one the market usually doesn't need them to. Scott Helms Vice President of Technology ZCorum (678) 507-5000 -------------------------------- http://twitter.com/kscotthelms -------------------------------- On Tue, Jul 22, 2014 at 2:39 PM, Mikael Abrahamsson <swmike@swm.pp.se> wrote:
On Tue, 22 Jul 2014, Scott Helms wrote:
One of the main problems with trying to draw the line at layer 1 is that
its extremely inefficient in terms of the gear. Now, this is in large part a function of how gear is built and if a significant number of locales went in this direction we _might_ see changes, but today each ISP would have to purchase their own OLTs and that leads to many more shelves than the total number of line cards would otherwise dictate. There are certainly many other issues, some of which have been discussed on this list before, but I've done open access networks for several cities and _today_ the cleanest situations by far (that I've seen) had the city handling layer 1 and 2 with the layer 2 hand off being Ethernet regardless of the access technology used.
Stop doing PON then. Use point to point fiber, you get 40-48 active customers per 1U. I'd imagine there might be newer platforms with even higher densities.
Yes, there are many examples of L2 being used but in order to deliver triple play the L2 network won't be purely L2, also BCP38 needs it to start doing L2.5+ functions, meaning it's harder to deploy new servies such as IPv6 because now the local network needs to support it.
It's cleaner just to do L1 and aggregate thousands or tens of thousands of residential properties in the same place.
-- Mikael Abrahamsson email: swmike@swm.pp.se