As with Openreach / BT / BT Openreach, the "handover node" terminology is troubled, as Bob and I have discussed by PM.
Openreach's own documentation uses "handover node" (see, for example, the picture in this
GEA Cablelink data sheet, where "NGA Hand Over Node" is used - NGA is "Next Generation Access", one of the acronyms applied to the Openreach FTTx system).
I chose to 'black box' BT Wholesale by saying:
An ISP must use the BT Openreach network to the BT Openreach handover node. From there, it's up to the ISP how much it provides itself and how much it buys from other companies.
In this context, I was merely trying to draw out that different ISPs use different backhaul, and it is the availability of the different backhaul networks at the relevant Openreach fibre handover node that determines which FTTC ISPs you can order from.
For anyone interested in opening the 'black box' and delving into the architecture of the BT Wholesale networks, I commend Bob's post.
Unfortunately,
BT SIN 472, which documents BT Wholesale WBC, is extremely technical. In
Section 5, the terminology used for the nodes Bob refers to is WBC PoSI node (Point of Service Interconnect), with an associated virtual router for the ISP termed an AP (Aggregation Point) and an EP (Extension Path) to connect the AP to the ISP's core network.
WBMC Shared, the service where BT Wholesale provide presence at the 20 WBC PoSI nodes and the 10 nodes where 20CN traffic is available for interconnect in a 21CN like manner (referred to as "IPStream Connect BRAS nodes" in section
3.3.3 of BT SIN 482) and aggregates the traffic on a shared network before delivering it across Host Links to the ISP adds a further level of complexity on top of WBC. There's a diagram in
section 4.1 of SIN 471 that gives a high level overview.
There's also a more bespoke version of WBMC called
WBMC Dedicated, which allows larger ISPs to have WBMC bandwidth dedicated to them from one or more of the WBC PoSI nodes and IPsC BRAS nodes. They can use WBMC Shared for any nodes where they don't have WBMC Dedicated presence, or they can use WBC at those nodes and haul that traffic back to their network themselves (though
a WBMC and WBC mixture is a complex setup that BT Wholesale don't recommend).
The more you delve into WBC, WBMC and IPsC, the more levels of complexity are revealed. What I don't see is "handover node" anywhere in the documentation, but I wouldn't be surprised if it was used somewhere.
In the context this arose - which ISPs are available from a particular FTTC line, I'm sure 'black boxing' BT Wholesale was the right decision!