th two separate T-GMs, each with its own IP address. One expects that the network, fully provisioned with boundary clocks between the T-GM (IP ad- dress of 10.2.2.2) and the slave, would deliver the most accurate clock. The unaware network between the slave and the T-GM (IP address of 10.1.1.1) is likely to be producing bad PDV with substantial asymmetry. However, with all else being equal, it is very likely the aBMCA will select the GM across the un- aware network because it is "closer" to the T-GM when comparing the steps Removed parameter. This situation would not arise with a deployment of the G.8275.1 profile. The operator must estim- ate and provision the best path manually using local priorities, or some other mechanism, because PTP does not know anything about the network path beyond an IP address. Managing the configur- ation on the slave to select the best path to the closest master is a significant operational burden in a large network. The other major difference between G.8275.1 and G.8275.2 is the treatment of the PTSF event, which is a means to signal the failure of the PTP messages on the slave. Although G.8275.1 relies on the Announce timeout mechanism to indicate loss of packet timing, the G.8275.2 mechanism is more thorough, which is not surprising considering the use of a wide-area routed network as a trans- port. Note that the very latest revisions to G.8275.1 are introducing the PTSF concept to this profile as well. The use case for G.8275.2 is those circumstances where an operator needs frequency and phase tim- ing and yet does not have the ability to have a network offering full on-path support. This situation arises when an operator may not own their own transport network and is relying on circuits carried over third-party networks. A very common scenario is to use G.8275.2 as a backup to a GNSS re- ceiver at the cell site using the APTS approach. Chapter 9 provides much more information on this topic. 7.5.1 Profiles for Other Industries This chapter has covered the original IEEE 1588-2008