HSL
From TBwiki
High Speed Link (HSL) refers to a single MTP2 link that uses the entire bandwidth of a trunk to transport MTP2 data. The difference between a HSL MTP2 link and a Nx64/56kbps MTP2 link is that the Nx64/56kbps link uses many (N) independent timeslots, each containing a HDLC receiver/transmitter, grouped logically into a single MTP2 link. On the other hand, the HSL link is really a single HDLC receiver/transmitter that is not bound by a timeslot's normal 7/8 bit boundary. Instead, it uses the complete trunk frame's potential bandwidth to transmit data. A Nx64/56kbps link can be switched via digital cross-connect equipment that handles the timeslot level (also referred to as 'channelized') while a HSL-type link cannot.
