Local Area Networks (LANs) in Aircraft - FTP Directory Listing - FAA

Interface
Customer’s Application Layer
Customer’s Transport Layer
Customer’s IP Layer
Service Provider IP Layer
Data Link Layer
Original
Private
Customer
Network
Packet
Encapsulated
Packet
Header
from
Service
Provider
Figure 22. Customer’s L3VPN Protocol Stack Shown Within the Network Service
Provider’s Network
Specifically, the service provider provides an interface above its own IP layer for the customer to
use to access the service provider’s network. Figure 22 shows a common L3VPN protocol stack
example where two IP layer protocols exist: one for the virtual network (i.e., the underlying
service provider network) and one for the customer’s own IP. Because the service provider’s IP
layer is an encapsulating redundant IP instance, it ensures that end-systems within the two
network systems cannot communicate or be aware of each other (i.e., end-systems have only one
IP layer protocol, not two). In this manner, the customer uses the service provider’s network
without being aware of other traffic using that same network, because the network traffic within
the service provider’s network occurs at the encapsulating IP layer, which the customer cannot
see. It is similarly unable to access any devices directly attached to that network, nor can those
devices access the customer’s network because they only support a single IP layer and cannot
see an (encapsulated) two IP layer protocol stack. It should be explicitly noted that the virtual
part of the VPN occurs because of the abstraction that the service provider’s network is solely
supporting the customer: The other customers using that network infrastructure are not aware of
each other’s existence. L3VPNs are, therefore, an instance of multilevel network systems (see
section 5.4.3).
RFC 4110, RFC 4111, and RFC 4176 provide architectural guidance for the creation of L3VPN
network deployments. L3VPNs are an instance of multilevel network systems (see section
5.4.3).
5.7 SECURITY ZONES AND POLICY-BASED NETWORKING.
Policy-based networking (PBN) is a mechanism to create adaptive networking systems that
continuously tune the network to achieve goals established by the network administrator. For
example, it promises enterprises the ability to define business rules that can be translated into
security or QoS policies that configure and control the network and its services as they evolve
over time. While the approach sounds directly relevant to the topic of this study, this section
explains why that is not the case. The final conclusion is that all open PBN alternatives have
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