rieve (GET) or update (SET) the value of the Announce timeout on a port. This book does not cover management nodes in any more depth, as they are not widely used and their use is not allowed in the telecom profiles. See Chapter 15 of IEEE 1588-2008 for further de- tails on management nodes and management messages. 7.5 Profiles By now, you should realize that the IEEE 1588-2008 specification is like a Swiss Army knife in that it contains any number of tools that can be applied to a multitude of tasks. The earlier section "Gen- eral Overview" mentioned that PTPv2 introduced the concept of profiles to PTP. Profiles allow an organization to design a specific implementation of PTP to apply to a specialized use case or application. The multitude of possible options means there is no point requiring that a network element should "support 1588-2008" with no further elaboration of the details. The preceding sections should demonstrate how many different methods are available in the 1588 standard, SO getting two PTP clocks to talk to each other means agreeing on a range of implementation options. There are domain numbers, TLV and dataset values, message rates, encapsulation, transport, and much more. To say a device "supports 1588" is like saying that it "supports routing." There are many different routing protocols, and they do not readily talk to each other. Of course, there are many elements of 1588-2008 that must be followed, but no vendor will imple- ment, validate, and support all the 1588 options under all circumstances. It makes sense that a smal- ler subset of the available options is chosen to implement a specific solution. It also makes predict- ing the performance more straightforward and vastly simplifies interoperability. This section covers the most important profiles, although there is an emphasis on the telecom pro- files, because they are the ones you are most likely to encounter in WAN topologies. 7.5.1 Default Profiles When IEEE 1588-2008 introduced the concept of profiles, it planted a seed by proposin