Page 97 - 5G Basics - Core Network Aspects

Core network aspects 1

additional complexity and high data-processing costs such as a complex tunnel negotiation process in IPsec
[b-Burger]. Furthermore, there are considerable performance issues on mobility-related network
equipments such as home agents and mobile nodes [b-IETF RFC 4093] [b-IETFRFC 5265]. In the case of VLAN,
the membership of VLAN should be determined prior to deploying VLAN, which requires static and complex
manual configuration by the network administrator. Also, VLAN suffers from scalability problems due to the
size of address space [b-Yu].
In addition, control of availability and performance and bandwidth guarantee for VPN and VLAN is difficult.
If more users are operating on the networks, the bandwidth of the VPN tends to decrease and affect users
of the entire system.
Network virtualization can provide LINPs by interconnecting virtual resources, but the interconnections may
be realized by various mechanisms not limited to conventional mechanisms according to user and service
requirements. Also, network virtualization can provide secure isolation among LINPs from various aspects,
including security, performance or management, and support diversity of application, service, network
control, management, and architectures.

7.2 Simplified access to resources
Networks typically consist of multiple heterogeneous physical resources such as routers and switches, but
the heterogeneity causes a difficulty in accessing and managing the networks. In order to manage whole
networks, network operators have to manage network resources with multiple types of equipment that may
have different types of access interfaces. Also, FNs will contain not only the legacy components from
networks, but also emerging new components from the development of up-to-date technologies. Thus, the
interoperability among heterogeneous network resources will become important for FNs. For these reasons,
access interfaces for different vendors have to be converged and managed on a common platform.

Network virtualization allows the abstraction of physical resources' characteristics so that other systems,
applications, or users can access the capabilities of resources by using abstracted interfaces [b-Vermesan].
These interfaces can guarantee compatibility for accessing the virtual resources and provide an efficient
control of the virtual resources.

7.3 Flexibility in provisioning
Flexibility refers to a capability of building a system, and expanding it as needed in order to adapt internal or
external changes [b-Browne]. In legacy networks, it is difficult to rapidly provide networks appropriate for
the requirements of various services because the provisioning of networks requires the actual deployment
of physical resources. It is also difficult to adapt to the environmental changes such as sudden traffic demand
changes and network failures by dynamically changing their configurations. Network virtualization provides
quick reconfiguration of LINPs to enhance flexibility to environmental changes.
In legacy networks, the scale of a network is restricted by the number of physical resources, so scaling out,
i.e., adding additional physical resources to the network, is one of the simple methods to increase scalability.
However, this approach cannot be done in a flexible manner because adding physical resources implies not
only hardware cost, but also maintenance and operations costs for floor space, operations, rack occupancy,
etc. Also, if traffic demand is over-estimated in the network-design phase, existing networks will suffer from
under-utilization.
Network virtualization allows the reuse of such resources, thereby achieving scalability and efficiency in the
use of network resources. Network virtualization allows adding or aggregating additional logical resources to
a virtual resource in order to provide increased capability at a lower cost than by adding physical resources.

7.4 Evolvability
If network providers want to deploy new network technologies and services or to migrate to a new network
architecture, they need to build a separate test-bed so that the behaviour of the new technologies and
services does not affect the current services. After evaluating the new technologies and services, network
providers will deploy them to their networks in service.

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