Version 4.1 - 1.2 OSI Layers
The OSI Model is a very basic concept.
All People Seem To Need Data Processing.
Application
Presentation
Session
Transport
Network
Data Link
Physical
This topic is on the CCNA level and you are taking the CCIE level exam. You know they won't be asking you any kind of straight-forward or obvious question on this topic. That would be too easy. So it's going to be tough to come up with any ideas regarding preparation for this. It's a 15 minute review.
This will refresh your memory and get the rust out - just in case you get the gift of a question on this topic. The only tricky thing I can come up with is a question on a PHYSICAL address - which relates to the Data Link layer. Stop and remember - physical address is a MAC address. And of course, you know MAC addresses are Data Link.
Encryption - > Presentation Layer. PPP -> Data Link Layer. This stuff is easy. So I looked really hard for something that might provide a bit more meat on the bone. The Wikipedia site (about half way down) has a section on Cross-layer functions. These are services that are not tied to a given layer, but may affect more than one layer. MPLS is one that is mentioned. Yeah, remember that's at "layer 2.5" - since it's a little Layer 2-ish and a little Layer 3-ish. ARP (translates Layer 3 to Layer 2 addresses) and DNS are also mentioned. Note: I disagree with the DNS being cross-layer. Everyone always puts that into Application. And ARP is usually considered Layer 2. But I can see where it might be considered cross-layer. And there is also Cross MAC and PHY Scheduling in wireless networks. [The Wikipedia link to this leads to a page that does not exist.]
Perhaps any new material that you are looking at may get the "what layer" question. So you may want to keep that in your mind as you study. But other than that, I'm really at a loss as to why this is on the CCIE Security Written blueprint. But I'm going to mark it off as done.