Bandwidth on Demand
Overview
Researchers today often need dedicated channels to transport data at higher bandwidth with guaranteed quality. Internet Protocol (IP) networks provide always-on services for data transfer but cannot guarantee this quality. Bandwidth on Demand (BoD) balances the use of the network by highly demanding applications, and prioritises traffic so that a faster and better level of service is received. The GÉANT2 network supplies the ability to transfer large amounts of information quickly and effectively, with capacity available whenever needed.
BoD activity is central to the efforts to develop the next generation GÉANT2 network, using transport technologies to offer new services in addition to IP-based services. The GÉANT2 Joint Research Activity 3 (JRA3) Automated Bandwidth Allocation across Heterogeneous Networks (AutoBAHN) system is working towards providing a BoD service by configuring on-demand circuits across various networks. These circuits will be reserved in advance.
Background to AutoBAHN
A new generation of applications that exhibit unprecedented network utilisation patterns is becoming ready to make use of the pan-European networking infrastructure. The emergence of GRID applications and peer-to-peer computing imposes new requirements on network services. These applications require high volume transfers (terabytes) at high capacity (several hundred Mbps), for extended periods of time (at least several hours). This is in contrast to the current typical use of networks where sessions are normally short-lived and of relatively low volume (up to a few Mbps). In order to meet the needs of both advanced and traditional users of the network, control mechanisms will be required, both to manage and balance use of the networks by highly demanding applications, and to categorise and prioritise traffic flows so that they receive the agreed level of service from the network.
For these applications to operate efficiently, the assignment of appropriate service levels must be done automatically by the interaction of middleware with a network control plane, in accordance with policies agreed by the network’s management. The required services must be available, end-to-end, across multiple network management domains, and incorporate features such as advance reservations and comprehensive performance monitoring. In particular, the AutoBAHN system has been designed to allocate network bandwidth to applications both immediately and in advance. Allocations will be restricted to authenticated users, acting within authorised roles and the aggregate services made available must be monitored to ensure adherence to Service Level Agreements (SLAs), along with the performance delivered by the networks.
AutoBAHN at work
Networking resources are allocated, end-to-end, across multiple domains, creating a complex problem of coordination and dynamic re-configuration of resources within a number of administrative domains. The granularity of resource reservations in terms of bandwidth and duration is important, together with the required QoS parameters. Because not all National Research and Education Networks (NRENs) deploy the same type of technologies, there are different ways of providing BoD services. AutoBAHN is being designed to support:
- Extended Layer 2 Virtual Local Area Networks (VLANs)
based on gigabit-Ethernet (GE) connections. - Point-to-point switched Layer 1 connections (STM-1 to
optical wavelengths, 1GE, 10GE).
Typically, an end-point in a NREN A needs to make a connection to an end-point in NREN B, via the GÉANT2 network. To provide guaranteed end-to-end service with resource reservation, service requests must be co-ordinated across domains. This role is undertaken by instances of the AutoBAHN system deployed in each involved domain.
The AutoBAHN system will not act as a replacement for existing control plane, signalling and provisioning capabilities. Instead it provides an integrated business layer for co-ordinated inter-domain provisioning, complementing existing control plane capabilities (where they exist) with AAI, inter-domain routing functionality, inter-domain monitoring, and so on. It also substitutes for the control plane functions where those are not available. AutoBAHN, acting as the intermediary between users (or applications) and the network, interprets user requests and translates them to requests to the network. The network itself must specify to the middleware what services are available and their corresponding quality parameters.
Each network domain defines policies for use of networking resources as well as quality parameters and is able to express them through AutoBAHN. Users authenticated by identity and role may receive authorisation against the respective policies. The originality of AutoBAHN lies in ensuring that new network services are introduced to meet the requirements of next generation network users, overcoming the borders of physically and technically disjointed networks.
AutoBAHN Technical Overview
The AutoBAHN system is based on the Inter-Domain Manager (IDM), a module responsible for inter-domain operations of circuit reservation on behalf of a domain. This includes inter-domain communication, resource negotiations with adjacent domains, resource scheduling, and topology advertisements.
To build a real end-to-end circuit, the Domain Manager (DM) module is also required to manage intra-domain resources. This module is the part of the AutoBAHN system that needs to be tailored to the domain-specific conditions and has an interface to the local IDM which sits immediately above it.
The local Network Management System (NMS) or service provisioning system, monitoring infrastructure, administration policies, and security, may need to be adjusted for each networking domain making each DM implementation unique. However, the design of the DM has been optimised to support modular deployment and leverage the management infrastructure already deployed in any domain.
In each domain, the data plane is controlled by the DM module using a range of techniques, including interfaces to the NMS, signalling protocols, or network elements. A dedicated Technology Proxy module, as part of the AutoBAHN DM, allows the AutoBAHN system to support a range of technologies and vendors according to domain and global requirements.
AutoBAHN User Cases
The benefits of BoD services are most obvious where advanced requirements for network connectivity exist, especially when multiple domains are involved, capacity reservation needs to be supported in advance and circuits
must be realised and released in a dynamic manner. A number of user cases for AutoBAHN are under development, including scenarios involving the Large Hadron Collider (LHC) project – the latest and most powerful in a series of particle accelerators based at CERN in Geneva and the SCARIe project – aimed at building a distributed software correlator for real-time processing of astronomical electronically transmitted data. In these scenarios, reliable transfer of large amounts of critical data among multiple end-points will take place over AutoBAHN-enabled circuits. Dynamic allocation of BoD circuits will optimise the utilisation of the available network resources and will allow “on the fly” selection of the endpoints among which data is exchanged.
