 (vDU/vCU, MEC) have yet to be adequately researched. Adopting cloud principles may lead to mobile and/or transport operator VNFs running on the same physical platform as third-party AFs, and even completely unrelated computational tasks. While economically attractive multi-tenant hosting introduces novel attack vectors, including denial of service, informa- tion leakage (potentially including discovery of passwords, shared secrets, and credentials), data manipulation, resource access, and even gaining complete platform control. Until lately virtualization technologies were thought to prevent these attacks, but the recent discovery of a plethora of attacks exploiting speculative execution, instruction pipelining, and paged memory have demonstrated that almost all modern CPUs are vulnerable. 6.6.5.4.9 Timing We previously discussed the requirements and physical layer aspects of delivering highly accurate timing to base stations over the transport network. For the most stringent require- ments the network's physical layer is utilized for stabilizing frequency (since bit rates are orders of magnitude higher than packet arrival rates) while the upper layers take care of time accuracy with some help from the physical layer. MPLS and IP can't provide any of the required physical layer functionalities, simply because they don't define physical layers. Ethernet defines both layer 1 and layer 2, and is thus almost universally used for on-path support, even when forwarding is performed by a different protocol. The IETF TICTOC working group seriously considered an MPLS PTP encapsulation, but this never progressed to standard status. The ITU-T telecom profiles (ITU-T G.8265.1, ITU-T G.8275.1, ITU-T G.8275.2) use UDP/IP PTP encapsulations in order to simplifying address- ing, but still assume well-engineered networks and the use of on-path support as required, which in most cases is accomplished by means of an Ethernet underlay network (at very least to provide accurate time stamping). While it is extremely advantageous for P