 network and the transport system? For that case, the other option is to use the mechanism designed for the PTS case. 11.3.1 Partial Timing Support with G.8275.2 and GMs at the Edge The second network topology to consider is the case where the network provides either zero or only partial on-path support. For this case, the ITU-T G.8275.2 telecom profile is deployed as the method to carry frequency, phase, and time across the transport. The use of SyncE is optional but recommended if possible. As a rule, operators are deploying this approach only in limited circum- stances (where they have no other options), and in many cases, only in combination with APTS. Figure 11-7 illustrates what the network looks like in such a deployment. The timing signal is sourced from a PRTC (typically a GNSS receiver) either as a standalone device or embedded in some aggregation router. These signals are supplied to a T-GM function that generates the PTP mes- sage stream to carry phase and time. Optionally, SyncE is used to carry a frequency signal, but if SyncE is not available, then the frequency is also carried by the PTP. PTP-unaware PTP-unaware PTP-unaware network network network PRTC / T-GM PTP-unaware G.8275.2 T-TSC-P network element T-BC-P slave clock Figure 11-7 Transport of PTP and (Optional) SyncE Across a PTS Network If possible, network elements in the path between the T-GM and radio equipment should be con- figured either as a Telecom Boundary Clock with partial support (T-BC-P) (it can also be a Telecom Transparent Clock with partial support [T-TC-P]). Typically, the radio equipment has the last PTP clock in the chain embedded inside it and functions as a Telecom Time Slave Clock with partial support (T-TSC-P). The more nodes that can be configured as T-BC-P or T-TC-P, the easier it will be to make the solution work and the better the result will be. Because of the nondeterministic performance of the timing signal across such an unaware network, the GM needs to be quite close to the slave clock to reduce the amount of d