716 research outputs found
Application layer multicast algorithm
This paper presents a multicast algorithm, called MSM-s, for point-to-multipoint transmissions. The algorithm, which has
complexity O(n2) in respect of the number n of nodes, is easy to implement and can actually be applied in other point-to multipoint systems such as distributed computing. We analyze the algorithm and we provide some upper and lower bounds for
the multicast time delay.Peer Reviewe
Application Layer Multicast Extensions to RELOAD
Native multicast deployment is relatively slow and linked with a number of issues. However, there are a number of native multicast regions. Application Layer Multicast (ALM) can be used in areas of the network where there is no native multicast available. The SAM (Scalable Adaptive Multicast) Research group within the IRTF is investigating hybrid approaches to multicast, involving native deployments were available and ALM in other regions. SAM is using a P2P overlay to connect the nodes. Here we describe a protocol and API extensions to RELOAD for constructing Scalable Adaptive Multicast (SAM) sessions using hybrid combinations of ALM, native multicast, and multicast tunnels. The Automatic Multicast Tunneling (AMT) relay and gateway elements are employed for interoperation between native regions and ALM regions
Analysis of the NICE Application Layer Multicast Protocol
Application layer multicast protocols organize a set of hosts into
an overlay tree for data delivery. Each host
on the overlay peers with a subset of other hosts. Since
application layer multicast relies only on an underlying
unicast architecture, multiple copies of the same packet
can be carried by a single physical link or node on the
overlay. The stress at a link or node is defined as the
number of identical copies of a packet carried by that
link or node. Stretch is another important metric in
application layer multicast, which measures the relative
increase in delay incurred by the overlay path between
pairs of members with respect to the direct unicast path.
In this paper we study the NICE application layer multicast
protocol to quantify and study the tradeoff between these
two important metrics --- stress and stretch in scalably building application layer multicast paths.
Also UMIACS-TR-2002-6
Flexible Application-Layer Multicast in Heterogeneous Networks
This work develops a set of peer-to-peer-based protocols and extensions in order to provide Internet-wide group communication. The focus is put to the question how different access technologies can be integrated in order to face the growing traffic load problem. Thereby, protocols are developed that allow autonomous adaptation to the current network situation on the one hand and the integration of WiFi domains where applicable on the other hand
Application-layer multicast algorithms for bounded delay transmissions
This work shows the design and study of a family of algorithms that solves the
multicast routing problem. In this problem, a given node called root has to send
information to a certain group of receiving nodes. Although the algorithm can
be applied at any level of the protocol stack, this paper studies its performance
in the application level. This family of algorithms provides optimal routing tables
between nodes belonging to the same multicast group, in such a way that the
total transmission time is minimum.
The algorithms take benefit from the delay time in the transmission of a
message between one peer and another to forward the data to a third peer.
Beginnig with a first algorithm, defined to send only one packet, some other
algorithms has been described under certain conditions to send more than a
packet with the maximum possible cadence and without congestion problems.
With this purpose, we have restricted the number of times that the root may
send a packet and also the maximum cadence time for the rest of the nodes.
Moreover, we have applied mechanisms to guarantee full connectivity.
With the aim of evaluating the performance of the different algorithms, we have
calculated theoretically a set of bounds for transmission delays. Moreover, we
present a serie of simulations over a virtual network that models an IP network.
Over that first network, we have defined a second network of user nodes,
which has been created at application level (so we can call it overlay network).
We have applied the algorithms over the overlay networks, obtaining delay
times, cadence times, number of nodes with congestion problems, and routing
trees.
Finally, we compare the results to check the best algorithm in any case. As
expected, the fastest algorithms can usually have important congestion issues
(more than a 50% of affected nodes). Moreover, the algorithm defined to avoid
congestion has at most 50% bigger delay than the fastest algorithms, and
hence we finally advice its application in multicast transmissions
An adaptive membership management algorithm for application layer multicast
Due to deployment difficulty of network layer multicast, application layer multicast is considered to be a good substitute for massive P2P video/audio streaming in large networks. However, in application layer multicast, the participating users join and leave the on-going session at will. Therefore, a scalable and reliable group membership management algorithm is necessary due to the highly dynamic nature of the overlay network, built on top of the Internet. Gossip-based algorithms seem to be a solution. However, most gossip-based membership management algorithms lack flexibility, and are unable to adapt to the everchanging network dynamics, imposing roughly the same amount of overhead on the network. A new adaptive gossip-based membership management algorithm is proposed to bridge the gap. This algorithm captures the changes of the network and adjusts the parameter settings dynamically, bringing adaptivity and reducing overhead. Simulation results indicate a maximum of 50% reduction can be achieved in terms of network overhead on core network components, such as backbone links and attached routers, without sacrificing reliability and scalabilit
Web Conferencing Traffic - An Analysis using DimDim as Example
In this paper, we present an evaluation of the Ethernet traffic for host and
attendees of the popular opensource web conferencing system DimDim. While
traditional Internet-centric approaches such as the MBONE have been used over
the past decades, current trends for web-based conference systems make
exclusive use of application-layer multicast. To allow for network dimensioning
and QoS provisioning, an understanding of the underlying traffic
characteristics is required. We find in our exemplary evaluations that the host
of a web conference session produces a large amount of Ethernet traffic,
largely due to the required control of the conference session, that is
heavily-tailed distributed and exhibits additionally long-range dependence. For
different groups of activities within a web conference session, we find
distinctive characteristics of the generated traffic
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