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Research Interests
Current Projects
- RouteSeer: Overlay Node Placement
Service Overlay Networks have emerged as an important means of
providing new services on the Internet. Much of the current
research in designing such overlays assumes that the nodes
that comprise the network already exist on the Internet in
some form and do not go into the question of selecting the
nodes (more precisely, their location in the network
topology). We propose a two part technique for placing overlay
nodes in service overlays with the objective of ensuring that
each path between pairs of overlay nodes is ``protected'' by
an indirect path using an intermediate node. In our method,
overlay nodes are first placed ``close'' to the clients of the
service overlay. We then use a technique called
RouteSeer to place intermediate nodes by examining the routing
tables at the overlay nodes such that most overlay links are protected
by a disjoint path through an intermediate node. Using extensive
simulations, we show that RouteSeer can substantially reduce the
overlap between overlay links. We are currently extending this
technique to provide protection to overlay links in the face of
routing changes.
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RouteSeer: Topological Placement of Nodes in Service Overlays, Sridhar Srinivasan and Ellen Zegura, Georgia Tech College of Computing Technical Report GIT-CC-06-03, Jan 2006.
- Design of a distributed resource location service
We proposed a novel design for a service overlay to provide a resource
location service that maps resource names to network locations. The
service, called LUNA (for LookUp Network Addresses), can be used by
applications which need to store and retrieve highly dynamic user data
using queries on attributes such as network location, geographic
coordinates, etc. LUNA is intended to be a highly scalable and
reliable service which allows for searching on multiple attributes and
provides bounded response times for queries.
Past Projects
- Design of Overlay Multicast Trees
Overlay multicast trees are usually composed of end systems which can
have varying access links varying from a DSL line to gigabit links.
Previous research has mostly ignored the effect of serial access to
this link and its effects on overlay construction and use. We show
that the effect of this serialization can be significant when
constructing overlays for delay-sensitive data. We propose a technique
called Time Division Streaming (TDS) to optimize the use of
this access link by scheduling the data traversing this link among the
competing overlay links. TDS allows each overlay link to, in turn,
send large blocks of data through the access link. We show that
overlays constructed using TDS can substantially reduce the average
delay experienced by the nodes in the overlay.
- Evaluation of Landmark placement for Internet Coordinates
Several schemes for assigning coordinates to Internet hosts have been
proposed. These schemes work by using a small set of nodes called
"landmarks" to compute the coordinates of other hosts. We investigate
the effect of placement of landmarks on the performance of these
schemes. We show that with random placement, the estimation error of
these schemes varies widely and propose heuristics for placing
landmarks which work well in practice.
- Topology of unstructured peer-to-peer networks
I collaborated with Shashi Merugu on studying the topology of
unstructured peer-to-peer networks. We proposed a new method for
establishing connections in such networks which improves the
likelihood of finding files close to the query source while reducing
traffic on the network links.
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Adding Structure to Unstructured Peer-to-Peer Networks: the Role of
Overlay Topology, Shashi Merugu, Sridhar Srinivasan and Ellen Zegura,
Proceedings of ACM Networked Group Communications (NGC),
Springer-Verlag Lecture Notes in Computer Science, Vol. 2816, pp.
83-94, Munich, Germany, September 2003.
-
p-sim: A Simulator for Peer-to-Peer Networks, Shashi Merugu,
Sridhar Srinivasan and Ellen Zegura, Proceedings of IEEE/ACM
International Symposium on Modeling, Analysis and Simulation of
Computer and Telecommunication Systems (MASCOTS), Orlando, FL, October 2003.
- Study of DNS Performance
I collaborated with Richard Liston on a large-scale study of DNS
performance using active measurements. My role in the project involved
writing code for parsing logs and performing data analysis.
- M-coop: Distributed Network Measurements
Real-time network measurements can be used to improve performance of
existing Internet services and support the deployment of new services
dependent on performance information. Internet-wide measurement faces
numerous scaling-related challenges, including the problem of
deploying enough measurement endpoints for wide-spread coverage. We
proposed a distributed network measurement architecture called M-coop
for providing Internet-wide realtime performance measurements by using
a peer-to-peer network to both perform and distribute the performance
measurements.
-
M-coop:A Scalable Infrastructure for Network
Measurement, Sridhar Srinivasan and Ellen Zegura, Third IEEE Workshop
on Internet Applications (WIAPP '03), San Jose, CA, June 2003.
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Network Measurement as a Cooperative Enterprise,
Sridhar Srinivasan and Ellen Zegura, position paper in 1st International
Workshop on Peer-to-Peer Systems (IPTPS'02), Cambridge, MA, February 2002.
A revised version is available as part of the post-proceedings in
the LNCS Hot Topics (LNCS 2429) here.
