Hm, Neil, isn't the fact that we are in total agreement again one of the Signs of the Apocalypse? :-) "Neil J. McRae" <neil@domino.org> writes:

The solution to this is for someone to make a Channelised SONET/SDH interface.

Designers should look at the Cisco (sorry, Neil) CT-3 card: http://www.cisco.com/warp/public/733/CT3IP/ct3_ds.htm which takes in an electrical PDH 45Mbps DS3 circuit and pulls out 28 DS1s. This is a beautiful card for anyone aggregating lots of DS1s together, and I'm pleased Cisco built it. (Consider that two CT3s get rid of most of the equipment seen in this picture: http://www.stupi.se/Bilder/3266-2012-0599/jpg1/img0011.jpg) Unfortunately it's all on the U.S. PDH standard, but hey, what can you do? --:) Like you, I would like to see one deal with SDH/SONET, and be able to pull out European PDH formats as well as U.S. PDH formats. I believe there is a market for such a card that consists of more than just you and me, although big traditional telcos will still like the CT3 for a while to come (testing and procedures reasons mostly). For the moment, however, if you have a telco supplying you with U.S.-style PDH circuits over SONET, you can pull a DS3 trib out of an OC3, and drop that onto the CT3 card, and handle 28 DS1s that way. Eliminating the need for the DS3 tributary card at the MUX and pulling an optical connection into a router would be a Good Thing as a next step, and I think that Cisco understands this. I dunno what your vendors are up to, but hey, if they want to build such an interface, then that's way cool too. The end goals, just to amplify your comments, are: -- one pair of fibres from MUX to router -- many many many lines of various bandwidths encapsulated in that pair of fibres -- de/aggregation of things like STM-1/OC3 or faster bundles of PDH and SDH circuits to be done by the telco side -- SDH/SONET is cool, and worth paying for -- SDH/SONET is cheaper facilities-wise for telcos to provide Ultimately I would like to be able to divide telcos into two varieties: those that offer fast concatenated point-to-point bandwidth (STM-1c to STM-16c, for customer and inter-POP connections, for example), who will never need to worry about PDH equipment ever; and those who will aggregate large numbers of PDH circuits into SDH/SONET in the standard way (to talk to lower-speed customers). [*] This meshes nicely with the idea of evolving three principal types of IP routers: ones that handle a number of very fast POS ports (STM-16c is nice), ones that handle one or two very fast POS ports and have massive de/aggregation facilities, much like the Cisco CT3, only at larger scale, and ones that are "special case" boxes which trade off interface steroids for packet-per-second processing time and general computational steroids (right now these are generally what I would call "edge" boxes, for use principally in talking with peers and/or customers at exchange points where rate limiting and other policy issues; in the future they could be huge NAT boxes, or only heaven knows what :) ).

SDH and SONET are multiplexing technolodgies and I wish the router manufacturers would wake up and grab this idea.

Agreed! Talk to your vendors, I'll talk to mine. :-) Sean. Footnote: [*] For the sceptical, there are already alternative suppliers of high-speed concatenated SDH in Europe. The traditional PNOs so far Just Don't Get It, and will probably not take advantage of the potential revenue stream for a while yet (big hint: if you're a potential supplier of high-speed concatenated SDH and aren't seriously thinking of pricing a few percentage points off a linear extension of PTT tariffs, talk to me :) ). The traditional PNOs are also no longer the only options for offering up a bunch of PDH circuits concatenated into SDH/SONET, either, so they face competition on that front too.