TP sync messages to be multicast in large networks, the current ITU-T telecom profiles mandate unicast. However, they do specify automatically configuring slaves with IP addresses of potential master clocks via 1588's optional unicast discovery mechanism. 6.6.5.4.10 NFV/MEC As mentioned before (e.g. in Section 6.2), functionality virtualization is used in mobile net- works for the following types of NFs: 1. 3GPP-defined network nodes, e.g. AMF and CU; 2. Networking functionalities required by the transport network itself, e.g. wide area net- work (WAN) optimization, FM and performance monitoring probes and reflectors; 3. User-centric functionalities such as firewalls, support for location-based services, and IoT aggregation; 4. MEC (see Section 6.4). The first (and in many cases the fourth) of these involves functions belonging to the mobile operator, although the transport provider may provide the computational platform and 6 Enabling Technologies hosting services. The second function type focuses unambiguously on the needs of the trans- port provider (reducing costs, increasing automation), and is intended to be transparent to both mobile operator and end user. Items in the third category directly benefit the end user, and are frequently marketed by mobile operators, although they may be provided by third parties (a model facilitated by the 5G service-based architecture [SBA]). The first type is obviously tightly coupled with the functional split option being used, while the second type is only indirectly influenced by the split (being directly susceptible only to traffic characteristics such as data rate or delay constraints). In some cases type 2 VNFs may be slice-dependent, in which case they must be able to classify traffic to a slice as has been previously discussed. User functionalities are generally limited to backhauling (split option 1) where user IP packets are discernible. At NG interfaces these user packets are still transported in GTP-U tunnels, and there is a need to decapsulate (or at least snoop