ceiver obtains the right data at an appropriate speed.
In contrast, in an ICN, communications are made explicit within the
network stack: when a node sends a request for an object, it can understand if
that request has been satisfied. As such,
the communications model becomes
receiver-driven, without the need for
cooperation from the sender to achieve
in-order reliability. Through this, it
also becomes possible to perform flow/
congestion control by simply altering
the frequency of requests. Therefore,
sessions established between specific
parties become less necessary.
Scoping of content and location.
Currently, consumers are generally
identified by their location (IP address). Often, however, this is incorrectly used for scoping purposes. That
is, incorrect information is interpreted from the address. For instance,
the BBC iPlayer service can only be
accessed from U.K. IP addresses; consequently, this makes mobility difficult for legitimate U.K. residents who
may temporarily utilize connectivity
abroad. A similar problem emerges
in CDNs when attempting to utilize
IP addresses for selecting optimal
content replicas. This is because (at
request time) the CDN will utilize a
node’s location to resolve an optimal
source, even though the node may later
change its location.
In contrast, an ICN makes an explicit separation between the what (the
user or content) and the where (their
location). Thus, a node’s location can
seamlessly change while still maintaining a consistent name (and profile)
for the user. Through this, it would not
be necessary to (incorrectly) interpret
things from changing location-based
addresses; instead, such information
could be encapsulated within separate
node descriptions that the network
could then exploit (for example, for access control).
Resilience through replication. Information exchange in a host-centric
network is usually based on some
concept of location (for example, a
URL). As such, if the host identified in
the URL fails or, alternatively, if any
of the intermediate routers fail, the
content will become unavailable (this
is particularly prevalent in MANETs6
In contrast, an ICN does not bind
content to specific locations through
the use of host identifiers; instead, content is the key addressable entity. This
allows content to be stored anywhere,
potentially allowing local copies to be
retrieved. On the one hand, this can improve performance. 28 However, beyond
this, the effects of network failures can
also be mitigated. 31 This is because ICN
caching can increase the number of
potential end points for each request,
thereby adding redundancy.
Here, we briefly review some prominent ICNs, alongside their approaches
to handling mobility.
NDN14 is a prominent design (also
known as CCN and CCNx). Figure 1
provides an overview of its operation.
Content naming is based on a flexible
hierarchical structure, allowing a variety of namespaces. In NDN, a content
request is issued by sending an Interest packet, which is routed through the
network to an instance of the content.
figure 1. overview of nDn.
node A node B
figure 2. overview of Dona.