Technical reports

Elastic network control

Hendrik Jaap Bos

January 2000, 184 pages

This technical report is based on a dissertation submitted August 1999 by the author for the degree of Doctor of Philosophy to the University of Cambridge, Wolfson College.

Abstract

Connection-oriented network technologies such as Asynchronous Transfer Mode are capable, in principle, of supporting many different services. Control and management of these networks, however, are often rooted in the monolithic and inflexible design of a traditional telephone network. This is unfortunate as the speed at which new services can be introduced depends on the flexibility of the control and management system.

Recent attemps at opening up network control and management have achieved promising results. Using non-proprietary interfaces and strict partitioning of network resources, multiple control systems are allowed to be active simultaneously in the same physical network. Each control system controls a virtual network, i.e. a subset of the network resources. Success of this approach has been limited, however, due to the inflexibility of its software components. The way in which resources are partitioned, or virtual networks built, is determined once and for all at implementation time. Similarly, the control systems themselves are rigid. Building and running a specialised control system in a separate virtual network for each application area, although possible in principle, is too heavy-weight for many applications.

This dissertation presents a solution for these problems, the implementation of which is called the Haboob. It represents the next step in opening up the network, by permitting customisation of all aspects of network control, including the software components. For this purpose, an agent environment, called the Sandbox, was developed, which is both language and implementation independent, and general enough to be used for purposes other than network control as well. It includes a simple uniform way for agents on different nodes to interact. Various mechanisms enforce protection and access control.

Sandboxes have been successfully introduced to all components that make up the network control and management system. Code running in Sandboxes is able to extend or modify the functionality of the components. This is called elastic behaviour. The customisability of all aspects of network control and management eases the development of new services. It is shown how recursive repartitioning of resources allows for application-specific control at a very low level and even enables clients to differentiate the traffic policing associated with these partitions. Such low-level control by dynamically loadable code may lead to significant performance improvements. Elasticity has also been introduced to generic services, such as traders, and components on the datapath. Elastic behaviour allows network control and management to be completely open.

When multiple control systems are active, interoperability becomes extremely important. Existing solutions suffer from problems to do with translation of control messages from one domain into those of an incompatible neighbouring domain. These mappings are fixed and suffer from loss of information at the domain boundaries, leading to functionality degredation. This is solved by making the mappings between domains programmable and by establishing inter-domain signalling channels across control domains with only limited functionality. In other words, the interoperability between control domains has been made elastic as well.

It is concluded that elastic network control and management eases the introduction of new functionality into the network.

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BibTeX record

@TechReport{UCAM-CL-TR-483,
  author =	 {Bos, Hendrik Jaap},
  title = 	 {{Elastic network control}},
  year = 	 2000,
  month = 	 jan,
  url = 	 {https://www.cl.cam.ac.uk/techreports/UCAM-CL-TR-483.pdf},
  institution =  {University of Cambridge, Computer Laboratory},
  doi = 	 {10.48456/tr-483},
  number = 	 {UCAM-CL-TR-483}
}