There is only the briefest mention in the Huawei docs to hand, but from what I see, the backplane remains unchanged. It's a dumb component anyway in the MA56xx.
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I take it to mean that the "subrack" is the cabinet or rack enclosure that holds the MA5616 chassis. Huawei sells such a beast - "an enhanced subrack" although why a different rack should be needed for vectoring?!
Thanks - I found the same hardware reference from that reference.
The subrack is indeed the steel box that the M5616 itself is mounted in, 19" x 3.5" (2U), and that all the linecards plug into. That kind of subrack is used to mount equipment in the 19" racks usually found in data-centres. Obviously our cabinets are cut & folded to provide the matching size of cutout, but vertically.
It is dumb, except for the backplane that the cards actually plug into - which help distribute comms and power between the various boards. Even the backplane might just be copper tracks on a PCB, or wires off sockets - but it is slightly less dumb than a steel box.
In some equipment, the external wiring goes to the backplane; in telco equipment the external wiring usually plugs into the front (as it does in our cabinets), leaving the backplane solely for wiring inter-board connections.
In this case it looks like the enhanced subrack contains an enhanced backplane, with additional communication channels between the boards - allowing the additional vectoring information to transfer between boards.
So it depends on the subracks that BT have ordered. If they're standard, there will be an outage while some hardware gets swapped in/out. It won't be a huge job, but it will be a site visit.
It looks like it employs a system level vectoring architecture. Though back in 2009, Huawei was prototyping node level vectoring with two or more cascaded MA5616 chassis. [2]
Excellent - that looks promising for a site with 2 Huawei cabinets then - we'll have to hope they don't mix vendor at different sites. It'd require some data transfer path between the 2 cabinets, presumably via the ducting.
[1] http://www.scribd.com/doc/126007087/Huawei-SmartAX-M...
[2] http://downloads.lightreading.com/wplib/huawei/Resea...
You always give excellent references. Much appreciated!