4 research outputs found
SIMULATIVE ANALYSIS OF ROUTING AND LINK ALLOCATION STRATEGIES IN ATM NETWORKS
For Broadband Integrated Services Digital (B-ISDN) networks ATM is a promising technology,
because it supports a wide range of services with different bandwidth demands,
traffic characteristics and QoS requirements. This diversity of services makes traffic control
in these networks much more complicated than in existing circuit or packet switched
networks. Traffic control procedures include both actions necessary for setting up virtual
connections (VC), such as bandwidth assignment, call admission, routing and resource
allocation and congestion control measures necessary to maintain throughput in overload
situations.
This paper deals with routing and link allocation, and analyses the performance of
such algorithms in terms of call blocking probability, link capacity utilization and QoS
parameters. In our model the network carries out the following steps when a call is offered
to the network:
(1) Assign an appropriate bandwidth to an offered call (Bandwidth assignment)
(2) Find a transmission path between the source and destination with enough available
transmission capacity (Routing)
(3) Allocate resource along that path (Link allocation)
We consider an example 5-node network [7], conduct an extensive survey of routing,
and link allocation algorithms. Regarding step (1) we employ the equivalent link capacity
assignment presented by various interesting papers [1]-[5]. We find that the choice of routing
and link allocation algorithms has a great impact on network performance, and that
different routing algorithms perform best under different network load values. Shortest
path routing (SPR) is a good candidate for low, alternate routing (AR) for medium and
non-alternate routing (NAR) for high traffic load values.
Concerning link allocation strategies, we find that partial overlap (POL) strategies
that seem to be able to present near optimal performance are superior to complete sharing
(CS) and complete partitioning (CP) strategies. As a further improvement of the POL
scheme, we propose a 2-level link allocation algorithm, which yields highest link utilization.
In this scheme, not only the accesses of different service classes to different virtual
paths (VPs) are controlled, but also an individual VP's transmission capacity is optimally
allocated to the service classes according to their bandwidth requirements in order to
assure high link utilization. This method seems to be adjustable to the fine degree of
granularity of bandwidth demands in B-ISDN networks.
It is shown that in order to minimize cell loss the call level resource allocation
plays a significant role: networks with the same buffer size switches display different cell
loss probabilities in the nodes and impose different end-to-end delay on cells if the link
allocation and routing differ. Again, we find that when traffic is tolerable by the network,
SPR causes the least cell loss. This can be explained by the fact that SPR spreads the
incoming calls in the network. It eagerly seeks new routes instead of utilizing the already
used but still not congested routes. SPR obviously wastes more rapidly link and buffer
capacity as traffic load becomes higher than the AR, which chooses a new route only
when it has to, i.e. when the route of higher priority becomes congested. That is why
we experience that as soon as the SPR starts loosing cells, it indicates that available
resources have been consumed and it rapidly goes up to very high blocking probabilities
after a small further increase of load
Application-Aware Analysis of Network Neutrality: A Scalable Real-Time Method
Internet access subscribers expect a satisfying quality of experience for any accessed service, independently from time, place, and service- and content-type. Besides the everincreasing amount of Internet data, the spectrum of video service platforms offering sharing and streaming also got significantly more comprehensive. Internet access providers try to avoid the exhaustion of network bandwidth by investing in network capacity or setting up higher-level resource management within their infrastructure. The primary question in this domain is how resource management constrains the subscriber to access an arbitrary service and experience good service quality.This question directly relates to network neutrality fundamentals. This paper presents a real-time full-reference objective method to assess network neutrality. It contributes three novelties to support user-centric analysis of potential restraints affecting Internet access quality: i) the proposal supports application-specific measurements and involves real content and real traffic, ii) the measured traffic originates from the content provider’s cloud infrastructure, iii) reference is created in real time. Accordingly, the proposal introduces a novel measurement layout. The key component is the emulated client that provides the real-time reference by emulating the access properties of the real client and accessing the same content simultaneously. We demonstrate the method’s feasibility with an applicationaware proof-of-concept use case: video streaming from a public VoD provider. We have validated the method against the emulated network parameters using an extensive series of laboratory measurements