James, regarding your uplinked post and in response to the SONET issue, it's not a matter of embracing it or not... it's very difficult to even get away from it. More below.
Here we see more confusion and the selective use of preferences on the part of the anti-sonet camp. The first thing that comes to my mind, if we are considering ascendant picks, is the preponderance of SONET that has been deployed by Northeast Optical Networks in their corridor. Most of the next-gen protocols supported by not only NOPT, but by most carriers, are supported by SONET, or SONET-defined interfaces on the optical network elements, such as DWDMs, and even on the so-called "all optical" switches. Take a look at the optical carrier line rates [ "OC-n" ratings ] on each. They are all defined in the SONET framing standards.
More to the point, almost all protocols today that are supported by WDM, despite the fact that some have removed the "self-healing" and other management features from the SONET layer (which some appear to be going back to, albeit in a more "next gen" way, as defined in several resilient packet ring technologies), still use the regular SONET framing and containerization at the interface level of optical elements: Packet over SONET, ATM over SONET, even GbE and 10GbE have their payloads supported by a Layer 1 that is SONET-defined in the gretaer number of cases. Long Cut, Short Take, or Rounded Corners... it's still Rock'n'Roll to me.
This explains why the next graduation of Ethernet in the WAN [which will very likely find its place in the MAN and Enterprise wiring closets, as well], beyond 10 GbE, is likely to be to 40 Gb/s instead of the usual step up to the next power of 10. Because Ethernet has now been assimilated at these levels into ITU-defined denominations of SONET/SDH.
At 10 Gb/s, Ethernet fits (more or less, make that less) into OC-192. At 40 Gb/s it will fit into OC-768.
SONET tends to step up using factors of 4. E.g., OC3/13/48/192/768/3072, whereas prior to Ethernet reaching 10 Gb/s, Ethernet used the next power of 10. E.g., 10/100/1,000/10,000 Mb/s.
Some, a lot, of the overhead of SONET will go away. But it's basic rate and framing constructs are likely to stay with us for a while, supporting a host of protocols and line coding techniques. Ironically, they are those very protocols and line techniques being supported by SONET that would seek to remove it, in the process. |
