Page 82 - 5G Basics - Core Network Aspects

1 Core network aspects

if the nodes have several network interfaces between them. Since different types of access networks have
different scopes in terms of coverage, one link failure due to movement outside the link coverage can be
compensated for by another link that is still connected to the other network.
Furthermore, application developers can benefit from DAN because of easy programming for network
application because they are not required to worry about the specification of network interfaces.

7.10 Traffic engineering of DAN
This service scenario takes advantage of the awareness feature of DAN, which inherently enables DAN
elements to identify not only individual flows of data objects on the network level, but also their features
such as the size or the service requirements of data objects. Thus, flows of data objects can be treated
differently by forwarding them through different paths depending on their service requirements. In IP
networks, an additional system component, e.g., deep packet inspection, is required to support such a
function. For instance, the problem of mice and elephant flows is well known: mice flows are short-lived data
flows such as emails, web pages, and data requests; on the other hand, elephant flows are long lived, such
as video streaming and data migrations, which significantly impact on network bandwidth and performance.

For dynamic operation of the service scenario when confronted with substantial data flow, DAN can be
managed in a centralized manner. A central management unit of DAN recognizes substantial data flow
coming into the network and dynamically sets up routes for the flow. For this reason, DAN elements are
deployed by operators for efficient use of network resources and fine control over user traffic.
Figure 7-19 depicts a sample scenario for DAN traffic engineering. This scenario assumes two types of
application: making phone calls; and downloading files. From the quality of service point of view, a phone
call service has higher priority than a file download service, since the phone call service requires minimum
packet loss and latency. To optimize data flows in this scenario, the two data flows are identified with their
names including labels specifying their service requirements: "Phone" for phone calling; and "FDS" for file
downloading.

1) User A requests User B for a telephone call. By the label "Phone" in the request message, e.g.,
"/Phone/UserA" and "/Phone/UserB", DAN elements are aware that the traffic is delay sensitive and
so forward the request message following the shortest path.
2) User B responds to the request and forwards the voice data objects to the DAN network. The voice
data objects are routed through the path that minimizes the delay. The caching function of DAN
elements on the path is disabled since it is a phone service.
3) During the phone conversation, User A requests an NDO from its file downloading service provider
with its name "/FDS/NDO", which represents delay insensitive traffic.

4) The service provider responds to the request and forwards the NDO to the DAN element. By the
name of "/FDS/NDO", the DAN element identifies that this is delay insensitive traffic flow and routes
it to the path that is not overlapped with the path taken by the voice data traffic flow, and that is
possibly having wider broadband. The cache function of the DAN elements on the path is enabled
to cache the NDO.

Figure 7-19 – Traffic engineering of DAN data flows

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