I recollect a table I saw last year, showed that the Huawei 288 is the largest FTTC cabinet.

The back-plane in the local one, has 300 sockets, split in to groups of 25.

Those groups are 5 rows of 5 sockets, the 5th, lowest, row being a different colour; and for some unknown reason, the right-most socket in that 5th row, is not used.

There are two columns of 6 groups each, giving 12 groups.

So in practical terms, it has 12 groups of 24 employable sockets, amounting to 288.

again locally, when first Released For Service in March 2014, only the the first and second groups in the left-hand column had the necessary Filter-Links plugged in, so only a temporary maximum of 48 Upgrades were possible.

I upgraded in June 2014.

About June 2015, the third and fourth groups in the left-hand column had Filter-Links added, raising the temporary maximum to 96 - assuming all were functional.

The technician adding those two groups had about 20 to 25 FTTCs scattered over quite a large, disparate area, to do.

In the next two months, there appeared to be a small flurry of upgrades done followed by very few.

About May 2016, talking to a different technician at the associated PCP, doing an upgrade, only about 63 were operational; and judging by the few subsequent visits, the total might be about 70.

The PCP appears to have 287 lines from a recent observation.


Hence "temporary maximums" lurching along until the FTTC is fully in use.

In reply to a post by eckiedoo:

I recollect a table I saw last year, showed that the Huawei 288 is the largest FTTC cabinet.

I believe Openreach now have higher port density cards which allow a single Huawei DSLAM to have more than 288 ports. These are used in situations where a 288 port configuration cabinet is full and it is more cost-effective to expand the existing cabinet than build a second fibre twin.

I can't find a reference quickly - can anyone else?

Huawei DSLAM 384HD.

Upgrades from 288 to 384 ports.

Apparently PCP199 in Basingstoke has had the upgrade to it already.

In reply to a post by eckiedoo:

Those groups are 5 rows of 5 sockets, the 5th, lowest, row being a different colour; and for some unknown reason, the right-most socket in that 5th row, is not used.

The connectors on the front of each DSLAM linecard in the 288 (2 connectors per card) each carry wires for 24 ports.

The layout of the filters, in groups of 24, means that the wiring (from filter to connector) follows a predictable pattern, and doesn't get mixed up. It makes the pre-cabling job a little easier, more predictable and repetitive, and likely to be higher quality and easier to test.

Why they chose a 5x5 layout rather than 6x4 or 8x3 remains unknown. Perhaps the available space was an a issue. Perhaps the sockets are cheaper in rows of 5.

Yes - 64 ports per card, instead of the original 48 ports.

http://www.ispreview.co.uk/index.php/2016/06/bt-open...

Thanks, WWWombat - another bit of the jig-saw now in place!

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With that 288 to 384 upgrade, is this done literally to an existing, say (approaching) fully-occupied 288; or is the 288 modified "in factory" before actual installation?

It seems a relatively extensive job to be done "in situ" in the street, as it would appear to require the temporary disconnection of all existing upgrades through that FTTC, possibly change of all Link Cable connectors etc; and the addition of two more Link Cables to the PCP.

Bearing in mind that for all the existing upgraded lines, their access back to the Exchange is now through the FTTC.

Loss of service?

Duct capacity?

Edited by deleted (Wed 20-Jul-16 19:32:33)

I'd expect it to be more of an in-place upgrade, though it is certainly possible for the factory to have started to churn out cabinets pre-built for 384 lines. If they did, I'd also guess they would do the wiring as properly built-in, rather than an add-on pod on the side.

There has been some debate about how you'd go about the upgrade in-situ.

The current style of connector can handle up to 32 ports - and the smaller Huawei DSLAMs are wired with 4 cards of 32 ports each, with a single connector.

Huawei certainly have used a 2-connector linecard for not just the 48-port linecards but 64-port cards too ... these would appear, on the face of it, to require the cabinet to be rewired.

Rewiring sounds like too much of an outage, so it has been suggested that an adapter cable could be used, which knows how to separate the spare 8 lines from the card connector towards the new wiring. Less disturbance, but more prospect of failure in future decades.

We've also seen Huawei use an entirely different style of connector for some 64-port cards; these certainly would need an adapter.

In either case, the adapter would be fitted at the same time as the card swapped, so probably wouldn't result in much extra outage for existing lines, while the new tie cables (to PCP) can be added at leisure.

My thanks again.