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Optimizing Cloud Resources for Delivering IPTV Services through Virtualization
Vaneet Aggarwal, Vijay Gopalakrishnan, Rittwik Jana, Kadangode Ramakrishnan, Vinay Vaishampayan
Special Issue of IEEE Transactions on Multimedia: Cloud-Based Mobile Media: Infrastructure, Services,
2013.
[PDF]
[BIB]
IEEE Copyright
This version of the work is reprinted here with permission of IEEE for your personal use. Not for redistribution. The definitive version was published in 2012. , 2013-01-01
{Virtualized cloud-based services can take advantage of statistical
multiplexing across applications to yield significant cost savings. However, achieving similar savings with real-time services can be a challenge. In this paper, we seek to lower a provider's costs for real-time IPTV services through a virtualized IPTV architecture and through intelligent time-shifting of selected services.
Using Live TV and Video-on-Demand (VoD) as examples, we show that we can
take advantage of the different deadlines associated with each service to effectively multiplex these services. We provide a generalized framework for computing the amount of resources needed to support multiple services, without missing the deadline for any service. We construct the problem as an optimization formulation that uses a generic cost function. We consider multiple forms for the cost function (e.g., maximum, convex and concave functions) reflecting the cost of providing the service. The solution to this formulation gives the number of servers needed at different time instants to support these services. We implement a simple mechanism for time-shifting scheduled jobs in a simulator and study the reduction in server load using real traces from an operational IPTV network. Our results show that we are able to reduce the load by $sim24\%$ (compared to a possible $sim31.3\%$ as predicted by the optimization framework). We also show that there are interesting open problems in designing mechanisms that allow time-shifting of load in such environments.}
Path Inference in Data Center Networks
Aman Shaikh, Vijay Gopalakrishnan, Seungjoon Lee, Kyriaki Levanti, Hyong Kim, Emmanuil Mavrogiorgis
CNSM (Conference on Network and Service Management),
2012.
[PDF]
[BIB]
IFIP Copyright
The definitive version was published in 2012. , 2012-10-22, http://www.cnsm-conf.org/2012/index.html
{Data center networks have started to play increasingly important roles
in today's Internet. Popular web-based services and critical
enterprise applications are hosted in large data centers. More recent
advances like cloud computing and cellular-based data usage have only
increased the importance of data centers. With the increasing
importance, however, also comes increasing complexity. Supporting the
wide-array of applications and traffic types while meeting all
their performance and security requirements results in complex network
designs. The result of this complexity is that managing these networks
has never been more difficult.
In this paper, we focus on providing one of the key building blocks of
network management: the ability to determine how traffic flows in the
network. This information is fundamental to many different network
management tasks including troubleshooting, capacity
planning, and what-if analysis. Towards that end, we present Chartis, a
system which performs per-packet path inference in a data
center. Chartis takes as input device configurations and the
network's physical topology and outputs the path of a packet in the
network. Specifically, Chartis performs per-hop path inference based on a
simplified model of layer-3 routing, layer-2 switching, and the most
commonly used routing and forwarding mechanisms.
To show Chartis diverse applicability, we perform path inference
within a campus network and on multiple data centers serving the 3G
network of a major cellular service provider. Using routing information
collected from these networks, we validate the correctness of the inferred
paths. Our results show that Chartis can quickly and accurately
determine paths traversed by packets even in complex data center
networks, making it a valuable addition to a network operator's
toolbox.}
Optimizing Cloud Resources for Delivering IPTV Services through Virtualization
Vaneet Aggarwal, Rittwik Jana, Vijay Gopalakrishnan, Kadangode Ramakrishnan, Vinay Vaishampayan
FOURTH INTERNATIONAL CONFERENCE ON COMMUNICATION SYSTEMS AND NETWORKS (COMSNETS),
2012.
[PDF]
[BIB]
IEEE Copyright
This version of the work is reprinted here with permission of IEEE for your personal use. Not for redistribution. The definitive version was published in FOURTH INTERNATIONAL CONFERENCE ON COMMUNICATION SYSTEMS AND NETWORKS. , 2012-01-04
{Virtualized cloud-based services can take advantage of statistical multiplexing
across applications to yield significant cost savings to the operator. However,
achieving similar benefits with real-time services can be a challenge. In this
paper, we seek to lower a provider's costs of real-time IPTV services through a
virtualized IPTV architecture and through intelligent time-shifting of service
delivery. We take advantage of the differences in the deadlines associated with
Live TV versus Video-on-Demand (VoD) to effectively multiplex these services.
We provide a generalized framework for computing the amount of resources needed
to support multiple services, without missing the deadline for any service. We
construct the problem as an optimization formulation that uses a generic
cost function. We consider multiple forms for the cost function (e.g., maximum,
convex and concave functions) to reflect the different pricing options. The
solution to this formulation gives the number of servers needed at different time instants to support these
services. We implement a simple mechanism for time-shifting scheduled jobs in a
simulator and study the reduction in server load using real traces from an
operational IPTV network. Our results show that we are able to reduce the load
by $sim24\%$ (compared to a possible $sim31\%$). We also show that there
are interesting open problems in designing mechanisms that allow time-shifting
of load in such environments.}
MPLS-TE in Networks With Varying Capacity Constraints
Kyriaki Levanti, Vijay Gopalakrishnan, Hyong S. Kim, Seungjoon Lee, Aman Shaikh
Kyriaki Levanti's PhD Dissertation,
2012.
[LINK]
[BIB]
Kyriaki Levanti Copyright
Kyriaki Levanti's PhD Dissertation
{}
Understanding Couch Potatoes: Modeling Interactive Usage of IPTV at large scale
Vijay Gopalakrishnan, Rittwik Jana, Kadangode Ramakrishnan, Deborah Swayne, Vinay Vaishampayan
IMC 2011,
2011.
[PDF]
[BIB]
ACM Copyright
(c) ACM, 2011. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in IMC 2011, 2011-11-02.
{We investigate how consumers view content using Video on
Demand (VoD) in the context of an IP-based video distribution
environment. Users today can use advanced stream
control functions like skip and replay in addition to play,
fast-forward, rewind, pause etc., to interactively control their
viewing. Such stream control, however, places additional
demands on the distribution infrastructure (servers, network,
and set top boxes) and can be challenging to manage with a
large subscriber base. A model of user-interaction is useful
to provide key insights on their impact on server and bandwidth
requirements, client responsiveness, etc.
We capture user activity in their natural setting of viewing
video at home. We first develop a model for the arrival
process of requests for content. We then develop two stream
control models that accurately capture user interaction. We
show that stream control events can be characterized by a finite
state machine and a sojourn time model, parametrized
for major periods of usage (weekend and weekday). Our
semi-Markov (SM)model for the sojourn time in each stream
control state uses a novel technique based on a polynomial fit
to the logarithm of the Inverse CDF. A second Constrained
model (CM) uses a stick-breaking approach familiar in machine
learning to model the individual state sojourn time
distributions. The SM model seeks to preserve the sojourn
time distribution for each state while the CM model puts a
greater emphasis on preserving the overall session duration
distribution. Using traces across a period of 2 years from
a large-scale operational IPTV environment we validate the
proposed model and show that we are able to faithfully predict
the workload presented to a video server. We also provide
a synthetic trace developed from the model enabling
researchers to also study other problems of interest.}
Seamless Access Router Upgrades through IP/Optical Integration
Vijay Gopalakrishnan, Emmanuil Mavrogiorgis, Jennifer Yates, Susan Bailey, Jorge Pastor
OFC/NFOEC 2011 Technical conference,
2011.
[PDF]
[BIB]
Optical Society of America Copyright
The definitive version was published in proceedings of OFC 2011 (Optical Society of America). , 2011-03-06
{We describe RFC, a new capability that minimizes customer outages during software and hardware upgrades in ISP networks. RFC is being used by a large Tier-1 ISP to upgrade access routers supporting thousands of customers.}
Nemor: A Congestion-Aware Protocol for Anonymous Peer-based Content Distribution
Fang Yu, Vijay Gopalakrishnan, David Lee, K. K. Ramakrishnan
Proceedings of IEEE P2P,
Submitted to IEEE International conference on Peer-to-Peer Computing (P2P 2011),
2011.
[PDF]
[BIB]
IEEE Copyright
This version of the work is reprinted here with permission of IEEE for your personal use. Not for redistribution. The definitive version was published in IEEE International conference on Peer-to-Peer Computing (P2P 2011). , 2011-08-31
As content providers adopt peer-to-peer approaches for content sharing and distribution, they face new challenges in guaranteeing privacy to their clients. Participating peers can glean information from their communication with other peers, such as their identities or the shared data and use this information for malicious purposes. We present Nemor, a protocol that allows a requesting peer and a corresponding serving peer to communicate anonymously with each other and from other participating peers, while protecting the identity of the content being exchanged. Nemor relies on a trusted intermediary, such as a provider-managed tracker, to identify a potential serving peer. A peer in Nemor joins one or more trees. Using a combination of a random walk, a probabilistic jump from one tree to another and constrained flooding, the requesting and serving peer dynamically construct an overlay path between them. A key differentiator of Nemor is the integrated design of a congestion avoidance mechanism that yields significant performance benefits without compromising on anonymity. Using experimental results from PlanetLab and simulations with traces from an operational VoD system, we demonstrate that Nemor outperforms state of the art approaches like TOR and OneSwarm. Our results confirm that Nemor, while being resilient to attacks on anonymity, achieves high performance and scalability and is suitable for a range of applications, including distribution of large volume content, such as streaming video.
Exploiting Virtualization for Delivering Cloud-based IPTV Services
Vaneet Aggarwal, Xu Chen, Vijay Gopalakrishnan, Rittwik Jana, Kadangode Ramakrishnan, Vinay Vaishampayan
IEEE INFOCOM Workshop on Cloud Computing ,
2011.
[PDF]
[BIB]
IEEE Copyright
The definitive version was published in IEEE INFOCOM Cloud Computing Workshop , 2011-04-10
{Cloud computing is a new infrastructure environment
that delivers on the promise of supporting on-demand
services in a flexible manner by scheduling bandwidth, storage
and compute resources on the fly. IPTV services like Video
On Demand (VoD) and Live broadcast TV requires substantial
bandwidth and compute resources to meet the real time requirements
and to handle the very bursty resource requirements
for each of these services. To meet the needs of the bursts of
requests, each with a deadline constraint for both VoD and
LiveTV channel changes, we propose a resource provisioning
framework that allows these services to co-exist on a common
infrastructure by taking advantage of virtualization. We propose
an optimal algorithm that provides the minimum number of
servers needed to fulfill all requests for these services. We prove this
optimality in a general setting for any number of services with
general deadline constraints. By using real world data from an
operational IPTV environment, our results show that anticipating
and thereby enabling the delaying of VoD requests by up to 30
seconds gives significant resource savings even under conservative
environmental assumptions. We also experiment with different
scenarios (by varying the deadline constraints, changing the peak
to average ratios of the constituent services) to compute the
overall savings.}
Capacity Requirements for On-Demand IPTV Services
Kadangode Ramakrishnan, Pat Diminico, Vijay Gopalakrishnan, Rittwik Jana, Deborah Swayne, Vinay Vaishampayan
THE third International Conference on COMmunication Systems and NETworkS (COMSNETS 2011),
2011.
[PDF]
[BIB]
COMSNETS 2011 Copyright
The definitive version was published in COMSNETS 2011. , 2011-01-05, http://www.comsnets.org/
{Service providers are evolving to provide more video content on-demand. Customers like to watch a variety of entertainment content of their choice and at a time conducive
to their schedules. Catering to this ever-increasing user base requires careful provisioning by the providers to accommodate for both scale and interactivity. In this paper, we examine the usage pattern of several hundreds of thousands of consumers of a nationwide IPTV service, and confirm that viewers are indeed
migrating to what is called �time-shifted� viewing of television programming and movies using digital video recorders or on demand viewing. We also show how users of on-demand content interactively control their viewing experience using �stream control� functions such as fast-forward, rewind, skip, replay, etc. Through careful measurements on an IPTV server, we compute the load due to streaming and handling these stream control events. We then extrapolate from these micro-benchmark
measurement to predict the processing load imposed by users that would resort to using a �network-based� DVR capability if such a service were offered. We use both detailed trace-driven simulations and a simple operational-analysis based model to
predict the capacity requirements of the server complex in the VHO to serve a large population of customers (e.g. a densely populated city like Mumbai). We provide insights on the number of requests serviced by the server, the average time to service
these requests and the response time as perceived by the client.}
Optimal Content Placement for a Large-Scale VoD System
David Applegate, Aaron Archer, Vijay Gopalakrishnan, Seungjoon Lee, Kadangode Ramakrishnan
Proceedings of ACM CoNext 2010,
Submitted to ACM CoNext 2010,
2010.
[PDF]
[BIB]
ACM Copyright
(c) ACM, 2010. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in ACM CoNext 2010 , 2010-12-01
IPTV service providers offering Video-on-Demand (VoD) typically have many servers at each metropolitan office to store all the videos in the library. With the rapid increase in the VoD library size, it will soon become infeasible to replicate the entire library at each office. We present an approach for intelligent content placement that scales to large VoD library sizes (e.g., 100Ks of videos). We formulate the problem as a mixed integer program (MIP) that takes into account constraints
such as disk space, link bandwidth, and the skew in content popularity. To overcome the challenges of scale, we employ a Lagrangian relaxation-based decomposition technique that can find a near-optimal solution (e.g., within 1-2%) with orders of magnitude speedup, relative to solving even the LP relaxation via standard software. We also present simple strategies to address practical issues such as popularity estimation, content updates, short-term popularity fluctuation, and frequency
of placement updates. Using traces from an operational system, we show that our approach significantly outperforms simpler placement strategies. For instance, our MIP-based solution can serve all requests using only half the link bandwidth used by LRU cache replacement policy. We also investigate the trade-off between disk space and network bandwidth.
Characterizing Interactive Behavior in a Large-Scale Operational IPTV Environment
Vijay Gopalakrishnan, Rittwik Jana, Ralph Knag, Kadangode Ramakrishnan, Deborah Swayne, Vinay Vaishampayan
IEEE Infocom 2010,
2010.
[BIB]
{Interactivity is promised by IP-based content distribution, particularly with IPTV. We investigate the user viewing activity for broadcast TV, pre-recorded content using Digital Video Recording (DVR) and video on demand (VoD). Advanced stream control functions (play, pause, skip, rewind, etc.) provide users with a high level of interactivity, but place demands on the distribution infrastructure (servers, network, home-network) that can be difficult to manage at large scale. To support system design as well as network capacity planning, it is necessary to have a good model of user interaction. Using traces from a well-provisioned operational environment with a large user population, we first characterize interactivity for broadcast TV, DVR and VoD. We then develop parametric models of individual users stream control operations for VoD. Our analysis shows that interactive behavior is adequately characterized by two semi-Markov models, one for weekdays and another for weekends. We propose a parametric model for the underlying sojourn time distributions and show that it results in a superior fit compared to well known distributions (generalized Pareto and Weibull). In order to validate that our models faithfully capture user behavior, we compare the workload that a VoD server experiences in response to actual traces and synthetic data generated from our proposed models. }
The Effectiveness of Intelligent Scheduling for Multicast VoD
Vijay Gopalakrishnan, Rittwik Jana, Kadangode Ramakrishnan, Vaneet Aggarwal, Robert Calderbank, Fang Yu
ACM Multimedia 2009,
2009.
[BIB]
{Multicast has seen a resurgence in the recent past, driven by the need to efficiently disseminate large volumes of real-time content, especially with the growth of IPTV. Video-on-Demand (VoD) delivery by multicasting still remains a challenge. Requests for popular content can be aggregated and served by multicast groups, but it has always been uncertain as to how much aggregation can be achieved. In this paper, we show that combining a good data model and an intelligent scheduler can help us realize significant benefits through multicast. Our design investigates an Earliest Deadline First-like (EDF) scheduler that aims to schedule the transmission of video ``chunks" according to their deadlines over multicast groups. We show through analysis that a dynamic multicast approach we term EDF-D is optimal, and minimizes the number of chunks sent from the VoD server. We use VoD request data from an operational service to quantify the benefit of multicasting and the amount of aggregation. Specifically, we observe a significant reduction in server bandwidth when compared to traditional techniques like unicast (65\%) and cyclic multicast (58\%). Finally, we show that even with 50\% of the requesting users performing some amount of fast forwarding, there is negligible reduction in the amount of aggregation. Version 3 reflects the changes made to conform for the camera ready manuscript for ACM Multimedia 2009 conference. The technical material in this version has only been slightly modified to account for reveiwers' comments. }
Loss-tolerant Real-time Content Integrity Validation for P2P Video Streaming
Vijay Gopalakrishnan, Kadangode Ramakrishnan, Fang Yu, David Lee
Comsnets 2009,
2009.
[BIB]
{The use of peer-to-peer (P2P) mechanisms for content delivery is attractive to content and service providers alike. P2P data transfers offload the demand on servers and reduce the bandwidth requirements, with corresponding benefits of improved scalability and performance. This, however, poses interesting challenges in ensuring content integrity. Peers may be malicious and attempt to send corrupt and/or inappropriate content to disrupt the service. Consequently, service providers must provide clients with the capability to validate the integrity of content delivered from peers. This goal is particularly challenging in the context of streaming video because the content needs to be validated in real time. A practical solution must provide high integrity assurance while incurring low communication and computation overhead. In this paper, we present a packet-based validation approach for ensuring the integrity of data obtained from peers. Our proposed scheme randomly selects packets and validates their correctness. Through detailed experiments, we show that this mechanism is not only lightweight but is also able to detect content corruption with very high probability, thus protecting a service provider's content delivery service. }
CPM: Adaptive VoD with Cooperative Peer Assist and Multicast
Kadangode Ramakrishnan, Vijay Gopalakrishnan, Rittwik Jana, Divesh Srivastava, Bobby Bhattacharjee
2008.
[PDF]
[BIB]
{We present CPM, a unified approach that exploits server multicast, assisted by peer downloads, to provide efficient video-on-demand (VoD) in a service provider environment. We describe our architecture and show how CPM is designed to dynamically adapt to a wide range of situations including highly different peer-upload bandwidths, content popularity, user request arrival patterns (including flash-crowds), video library size, and subscriber population. We demonstrate the effectiveness of CPM using simulations (based on the an actual implementation codebase) across the range of situations described above and show that CPM does significantly better than traditional unicast, different forms of multicast, as well as peer-to-peer schemes. Along with synthetic parameters, we augment our experiments using data from a deployed VoD service to evaluate the performance of CPM. Original document was a presentation. This is a paper we have written, and submitted to a conference. The first author has also been changed. }
Distributed Ranked Search
Vijay Gopalakrishnan, Ruggero Morselli, Bobby Bhattacharjee, Pete Keleher, Aravind Srinivasan
HIPC,
2007.
[BIB]
{P2P deployments are a natural infrastructure for building distributed search networks. Proposed systems support locating and retrieving all results, but lack the information necessary to rank them. Users, however, are primarily interested in the most relevant results, not necessarily all possible results. }
System And Method For Content Validation,
Tue Jan 31 12:50:22 EST 2012
A method of obtaining content includes receiving a playfile. The playfile includes a chunk ID corresponding to a chunk of the content, a packet ID corresponding to a packet of the chunk, and a hash of the packet. The method further includes obtaining the chunk from a peer, determining a calculated hash for the packet, and discarding the chunk when the calculated hash does not match the hash in the playfile.
