Download system engineering and network architecture level

Systems Engineering and Network Architectures for Hybrid Communications
Figure 1 General Architecture Conceptualization
Overview
At the system engineering and network architecture level, our work has focused primarily
on the issue of mobile transient networks (ad-hoc and infrastructure networks) [1]. The
main thrust behind this approach is to separate the logical network infrastructure from the
physical one. In other words, and while the various components designed above are
connected physically to other components across a hybrid network, the logical network
aims at enabling seamless communication between mobile and stationary network entities
across multiple networks and through hybrid communication environments as depicted in
Figure 1. We have already exploited concepts such as persistent identification which we
believe is crucial to be able to connect a variety of heterogeneous devices in a network
that grows, and that is robust to failures. A vital characteristic of our architecture is the
ability to accommodate a variety of heterogeneous devices and subsystems, thus
providing an excellent candidate for designing and analyzing hybrid networks.
The integration of the heterogeneous networks depicted in Figure 1 is made possible
through a logical abstraction that constitutes of a set of systems, components and
mathematical notions. The most prominent of the concepts we introduced is the
conceptualization of networked entities as persistent transient mobile entities that are
uniquely and persistently addressed by the global system. In our approach to hybrid
network abstraction, each communicating resource is mapped into a digital abstraction,
which forms an entity that is uniquely identified by a persistent identifier. The digital
entities are considered persistent and independent of their current physical and
geographic attributes. This abstraction allows persistent addressing and communication
between these entities regardless of their current association, location or means of
communication in the hybrid environment. For example, the entity could move
seamlessly from one network environment to another and still be seamlessly
incorporated, provided it met the administrative requirements. Digital entities may be
networked sensors, end-points, users, applications, sessions, backbone building blocks
and even subsystems.
Part 1: Mobility and comm. across heterogeneous networks. [Henry/CNRI]
We have experimented with different kinds of digital entities. Specifically, we have
demonstrated in [2] a basic implementation of several systems and components that set
the ground for the existence of the hybrid aggregated network. We showed how mobile
and stationary network nodes (laptops, PDAs, …) can join the logical network and be
addressed uniformly and communicated with even when they moved between IPv4 and
IPv6 networks. We have also prototyped implementations of gateways that can expose
network devices using whatever communication mechanisms the devices support. Our
current implementation of the gateway allows devices (Laptops or limited resource
devices like PDAs and cell phones) to connect to the logical network and obtain their
global persistent identifiers, and thus become visible to other devices in the hybrid
network. The gateways can also translate traffic to these devices and interoperate with
current protocols and networks; for example, internet clients can reach the devices using
the traditional DNS protocol that is extended by a special type of gateway.
Part 2: SIP part with results [Ours]
In a parallel effort [3], we have experimented with users as digital entities in the context
of VoIP. We have implemented a test-bed that allowed roaming SIP users to be addressed
with persistent identifiers regardless of their domain bindings or network attachment
points. Users join the logical network to allow inter-domain registration, call routing and
authentication. In the same sense, we envision any entity (sensors for example) to be able
to seamlessly move between heterogeneous networks and still be reached and
communicated with independent of the particular communication details. Our approach
demonstrated more efficient security and routing mechanisms. So, as Figure 1 shows our
roaming model whereby the roaming user r_user is now able to securely use the closest
available SIP server instead of communicating back to his home server which could be in
another country. Figures 2and 3 show the registration/authentication model and the call
setup model respectively. In both figures, we depict the traditional sip flow (A) versus
our proposed flow (C). The performance results are depicted in Figure 4, where we
showed 5 to 7 times better performance for registration and as well a better call setup
performance. Our roaming approach can be extended across hybrid networks beyond the
constraints of SIP, for example, cell phones and sensors in communication devices.
Figure 2 Roaming model
Figure 3 Registration model
Figure 4 Call setup model
Figure 5 Performance results
Part3: Abstraction of core components – routers [Cisco project and Henry/CNRI]
Part of the realization of the logical architecture abstraction handles the heterogeneity of
the network at the hardware level. In this part of our research, we have succeeded to
abstract a network core device - router - by separating the hardware from the intelligence
of the actual device. Unlike current implementations where each device’s functionality is
specific to its particular hardware implementation, this approach isolates the actual
components of the device abstraction, itself expressing it as a digital entity. This is
achieved through a hardware-specific uniform layer that the digital entity can use to
interface with the underlying hardware. This intermediate layer embraces the hybrid
characteristics of most of the current devices and provides a standard means for
interaction between higher logical layers and pure hardware platforms. Hence, a novel
approach to communication organization, reconfiguration, management and security is
allowed. The hybrid communication resources are then turned into reconfigurable
commodities with different added values and the particular local implementations of the
transmission and reception paradigms are masked to provide a stable logical
communication layer. Towards this end, we have implemented a prototyped network that
demonstrates this abstraction. A sketch is available in Figure 2. The current
implementation focuses on routing at the overlay level (on top of IP). In other words, we
have decoupled the router’s hardware from its brains through the unifying interface. With
this framework, we are able to control every operation of a router on the fly through the
dissemination of persistently identified mobile agents. This allowed us to easily configure
and manage routing in the prototyped network, creating multiple virtual networks on top
of a volatile set of hardware. The virtual networks are self-configurable, self-healing and
much easier to administer. We have demonstrated how hardware failures on a particular
router will keep communication undisrupted thus fostering resilience. We have also
demonstrated seamless communication between pure IPv4 networks and pure IPv6
networks where network hosts were oblivious to the underlying hybrid infrastructure. In
other words, an IPv4 client was able to communicate with an IPv6 client using the latter’s
persistent identifier and vice versa. The clients, which are part of our implemented
network, required no configuration at all. The overlay routing infrastructure handled the
seamless transmission of traffic across the heterogeneous environments (IPv4 and IPv6).
As the current implementation is only a prototype at the overlay level, we plan to
implement the necessary interfaces and protocols at lower levels to foster the hybrid
communication. At this homogenizing level, heterogeneous hardware platforms that
constitute hybrid networks, can be interfaced uniformly. This will allow the network
brains (agents) to migrate among heterogeneous hardware platforms, configuring them,
routing traffic through them, enabling QoS network paths, preventing malicious attacks
(security) etc. This allows, for example, data routing to exploit multiple redundant paths
across different available communication environments.
Figure 6 Fully mixed network
Our network and nodes are therefore dynamic and clever structures that maximize and
profit from their hybrid characteristics for their own needs, as well as of the networks that
they are involved in while providing a common interface that enables seamless routing
administration and coordination. This abstracts the complexities of hybrid systems and
avoids the issue of interoperability and interconnectivity at the conceptual network layer.
It does so by masking it behind the concepts of identity persistence, abstract
representation and aggregated network consolidation.
The resulting network welcomes heterogeneity at the physical communication level and
provides the hardware resources with a mechanism that allows them to implement their
particular hardware specific needs while providing a global neutral interface to the
network and its applications.
In summary, the outcome of our proposed approach is a set of digital entities organized in
a logical architecture and capable of relocating, migrating, being stored, streamed,
disseminated and coordinated by means of their persistent identifiers regardless of their
current physical implementation and location.
References
[1] H. Jerez, C. Abdallah, and J. Khoury, “A mobile transient network architecture,”
2006, pre-print available at https://dspace.istec.org/handle/1812/55.
[2] J. Khoury, H. Jerez, N. Nehme, and C. Abdallah, “An application of the mobile
transient network architecture: Ip mobility and inter-operability,” 2006, pre-print
available at https://dspace.istec.org/handle/1812/54.
[3] J. Khoury, H. Jerez, C. Abdallah, "H-SIP: An Approach to Inter-Domain SIP
Mobility", submitted to Consumer Communications and Networking Conference, CCNC
2007.