Facilitating Adaptive Placement of Management and Control Functions in Converged ICT Systems - Advances in Network-Embedded Management and Applications - page 57

The authors of [24] also motivate the coexistence of centralized and
distributed management approaches, and concrete hybrid management
architectures are proposed, for instance, in [25], [26]. In these architectures,
more traditional centralized and weakly distributed management frameworks,
e.g. SNMPv1, SNMPv1 + RMON, and TMN [27] (indicated in Fig. 1
according to [8], [9], [10]), are combined with distributed management
approaches that make use of mobile agent technology (e.g. [28], [29]). It is
clear from these hybrid approaches that coexistence is vital for achieving
optimal performance when different management functions are to be
combined, such as high-level versus localized management.
Of specific interest to network virtualization in particular is the recently
proposed OpenFlow network switching technology [1], [2], which is
characterized by a centralized controller that manipulates traffic flows by
parameterizing the flow tables of individual network elements, which hence is
in direct opposition to distributed management frameworks. Complementary,
virtual switching in virtual machine monitors (hypervisors), such as [30],
provide new abstractions to manipulate multiple virtual switches (Open
vSwitches in [30]) to be controlled via a single logical image from a central
point. At the same time, trends towards deeper embedding of control functions
from host to programmable network interface card (NIC) space are pushed by
new performance constraints that are dictated by virtual switching in the host.
Such transitions are facilitated by e.g. [31] and lead to a shift of general
networking functions [32] and in particular OpenFlow-related functions [33],
[34] to the NIC.
3 Adaptive Placement of Management and Control Functions
In this section we introduce the principles and the framework for
implementing a management and control system that is suitable for
converging ICT systems. In particular, this system is focusing on the
facilitation of different degrees of distribution and hierarchies as we will
explain.