The BT Wholesale ISP Forum document (from 12th May) has a little to say about the subject of Retransmission on ECI:
- Openreach were removing retransmission on ECI
- The decision affects 260k lines
- Does not include multicast; decision due on those lines on 13th May
- The reason given: "we are experiencing a much higher than average fault rate for these lines"
- "Openreach working with its supplier"
- If I read it correctly, one item that BTW fed back to BTOR was: "ECI retransmission - why wasn’t it trialled more thoroughly?"
260,000 lines doesn't seem like a lot. Either there are a lot using multicast, or the rollout hadn't gone very far.
To check, I looked back at the cabinet composition data we got in Autumn 2014, as part of the application for unmetered power supplies. That data provided a snapshot for 34,000 cabinets (out of perhaps 55,000 that were installed at the time), of which 15,000 cabinets were ECI ones. The breakdown of ports in use suggested there were perhaps 750k lines on those 15,000 ECI cabinets at the time.
I would guess there has to be over a million lines in use now - even if most of the rollout since then has been Huawei.