200 S Laurel Ave - Rm A5-1D35
Middletown, NJ
Subject matter expert in network restoration, network design, algorithms
I am a Lead Member of Technical Staff in the Network Evolution Research Departmet of AT&T Labs - Research. My research interests are in the areas of network restoration, design, and architecture. Prior to joining AT&T, I worked at the routing and signaling group of Ciena CoreDirector switches and before that at the Networking Research Department of Lucent Bell Laboratories.
I received my B.Tech. (Computer Science) from Indian Institute of Technology (I. I. T.), Kanpur, India and my Ph.D. (Computer Science) from University of Washington, Seattle.
Multi-Layer Design of IP over WDM Backbone Networks: Impact on Cost and Survivability
Kadangode Ramakrishnan, Rakesh Sinha, Byrav Ramamurthy
DRCN 2013,
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 2013. , 2013-03-04
{To address the reliability challenges due to failures
and planned outages, Internet Service Providers (ISPs) typically
use two backbone routers at each central office in a dual-
home configuration. Thus at the IP layer, redundant backbone
routers as well as redundant transport equipment to interconnect
them are deployed to provide reliability through node and path
diversity. However, adding such redundant resources increases
the overall cost of the network. Hence, a fundamental redesign of
the backbone network which avoids such redundant resources by
leveraging the capabilities of an agile optical transport network
is a highly desirable objective.
In this paper, we propose such a fundamental redesign of
IP backbones that avoids redundant routers by exploiting the
capabilities of agile optical transport. Our alternative design uses
only a single router at each office but uses the agile optical
transport layer to carry traffic to remote Backbone Routers (BRs)
in order to survive failures or outages of the single local BR.
Optimal mapping of local Access Routers (ARs) to remote BRs
is determined by solving an Integer Linear Program (ILP). We
describe how our proposed design can be realized using current
optical transport technology. We evaluate network designs for
cost and performability, a metric combining performance and
reliability. Significant reduction in costs accrue for approximately
the same level of reliability as current designs.}
Cost Optimization Using Regenerator Site Concentration and Routing in ROADM Networks
Rakesh Sinha, Angela Chiu, Mark Feuer, Guangzhi Li, Sheryl Woodward, Weiyi Zhang, Balagangadhar G Bathula, Keren Bergman, Robert Doverspike, Peter Magill
DRCN 2013,
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. , 2013-03-04
{The advent of colorless and non-directional reconfigurable
optical-add-drop multiplexers (ROADMs) will enable
flexible pre-deployment of optoelectronic regenerators in future
optical networks. Compared to the current practice of installing
regenerators only when a circuit needs them, pre-deployment
will allow service providers to achieve rapid provisioning and
restoration. The pre-deployed regenerators should be concentrated
in a selected subset of ROADM sites in order to attain high
utilization and to reduce operational costs. We prove that the
resulting optimization problem is NP-hard and present an efficient
heuristic for this problem that takes into account both the cost of
individual circuits (regenerator cost and transmission line system
cost) and the probability of a given circuit request, as well as
the number of regenerator sites. We provide various methods
to reduce the number of regenerator sites, if low probability
demands are allowed to have slightly costlier paths. Specific
network examples show that the proposed heuristic has near
optimal performance under most studied scenarios. We present
results for several different cost models. We have also evaluated
the heuristic for survivable optical networks, in which a second,
disjoint path must be supported for each circuit.}
Simulations of a Service Velocity Network Employing Regenerator Site Concentration
Mark Feuer, Balagangadhar Bathula, Daniel Bihon, Angela Chiu, Inwoong Kim, Guangzhi Li, Paparao Palacharla, Rakesh Sinha, Xi Wang, Sheryl Woodward, Weiyi Zhang
OFC/NFOEC2012 conference,
2012.
[PDF]
[BIB]
Optical Society of America Copyright
The definitive version was published in OFC/NFOEC2012 conference. , 2012-03-04
{We use Monte Carlo simulations of quasi-static traffic growth to study concentration of regenerator sites in dynamic photonic networks supporting service velocity. Idle regenerators can be reduced by >60% compared to unrestricted regeneration sites.}
On Concentrating Regenerator Sites in ROADM Networks
Rakesh Sinha, Angela Chiu, Guangzhi Li, Weiyi Zhang, Mark Feuer, Sheryl Woodward, Balagangadhar G. Bathula, Keren Bergman, Inwoong Kim, Paparao Palacharla
OFC/NFOEC2012 conference,
2012.
[PDF]
[BIB]
Optical Society of America Copyright
The definitive version was published in OFC 2012. , 2012-03-04
{Concentrating optical regenerators in a subset of network nodes provides significant savings. We present a
heuristic for choosing this subset. Our results are within 1 or 2 of optimal in the studied cases.}
Cost and Reliability Considerations in Designing the Next-Generation IP over WDM Backbone Networks
Byrav Ramamurthy, Kadangode Ramakrishnan, Rakesh Sinha
International Conference on Computer Communication Networks (IEEE ICCCN 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 International Conference on Computer Communication Networks (IEEE ICCCN 2011). , 2011-07-31, http://icccn.org/icccn11/
To accommodate the increasing demands for bandwidth,
Internet Service Providers (ISPs) have deployed higherspeed
links and reconfigurable optical add drop multiplexers
(ROADMs) in their backbone networks. To address the reliability
challenges due to failures and planned outages, ISPs typically
use two backbone routers at each central office in a dualhome
configuration. Thus at the IP layer, redundant backbone
routers as well as redundant transport equipment to interconnect
them are deployed to provide reliability through node and path
diversity. However, adding such redundant resources increases
the overall cost of the network. Hence, a fundamental redesign
of the backbone network which avoids such redundant resources
by leveraging the capabilities of an intelligent optical transport
network is a highly desirable objective. It is clear that such a
redesign must lower costs without compromising on the reliability
achieved by today�s backbone networks. Modeling the costs and
reliability of the network at all layers is an important step in
achieving this objective. In this paper, we undertake an in-depth
investigation of the cost and reliability considerations involved
in designing the next-generation backbone network. Our work
includes a detailed analysis of the operation, cost and reliability
of the network at the IP layer and the multiple layers below it.
We discuss alternative backbone network designs which use only
a single router at each central office but use the optical transport
layer to carry traffic to routers at other offices in order to survive
failures or outages of the single local router. We discuss trade-offs
involved in using these designs.
A network design technique for selective restoration
Kostas Oikonomou, Robert Doverspike, Rakesh Sinha
OFC 2011,
2011.
[PDF]
[BIB]
Optical Society of America Copyright
The definitive version was published in proceedings of OFC 2011 (Optical Society of America). , 2011-03-09
{We outline a network design technique that exploits differences in the failure
rate and impact of network elements to produce a more efficient design. We
demonstrate its efficacy on a Tier-1 backbone network.}
Proactive Network Management of IPTV Networks
Rakesh Sinha, Kadangode Ramakrishnan, Robert Doverspike, Dahai Xu, Jorge Pastor, Aman Shaikh
2010.
[PDF]
[BIB]
{Consumer communications and entertainment services, including broadcast TV and VoIP require service providers to meet stringent availability and latency constraints. When a packet technology, such as IP, is used to transport these services, this also poses stringent packet loss requirement on the network. This aspect of IPTV, where impairments have consumer-visible impact and potential public relations consequences, creates new challenges in protocol design, as well as network management. The key to operating an effective network is to expand beyond the typical ?reactive? network management approach to be able to anticipate and manage potential network problems. This paper describes network management techniques deployed in a production IPTV network with over 2 million customers. }
Cross-layer Reconfiguration for Surviving Multiple-link Failures in Backbone Networks
Ajay Todimala, Kadangode Ramakrishnan, Rakesh Sinha
2008.
[PDF]
[BIB]
{}
Performability analysis of multi-layer restoration in a satellite network
Kostas Oikonomou, Kadangode Ramakrishnan, Robert Doverspike, Angela Chiu, Rakesh Sinha, Miguel Martinez-Heath
2007.
[TXT]
[BIB]
{Abstract. The ability of an IP backbone network to deliver robust and dependable communications relies on quickly restoring service after failures. Service-level agreements (SLAs) between a network service provider and customers typically include overall availability and performance objectives. To achieve the desired SLA, we have developed a methodology for the combined analysis of performance and reliability (performability)of networks across multiple layers by modeling the probabilistic failure state space in detail and analyzing different restoration alternatives. This methodology has been used to analyze large commercial IP-over-Optical layer networks. In this paper we extend our methodology to evaluate restoration approaches for an IP-based satellite backbone network. Because of the environment in which they operate (long delay links, frequent impairments), satellite networks pose an interesting challenge to typical restoration strategies. We describe the potential multi-layer restoration alternatives and compare their performability. Interestingly, while it is commonly thought that SONET ring restoration at the lower layer improves overall reliability, we find that it may not always improve performability in this environment. }
Cross-Layer Reconfiguration Method For Surviving Multiple-Link Network Failures,
Tue Aug 14 16:11:25 EDT 2012
A second link in a network is reconfigured after failure of a first link, so that multiple-link failures may be survived. After receipt of an OSPF link state advertisement (LSA) indicating use of a backup path b.sub.l after the failure of link l, new backup paths are determined for each impacted link (x,y) that has a backup path sharing one or more links with the backup path b.sub.l. The new backup paths are computed while ignoring the failed link l, the impacted link (x,y), and links common to the backup paths b.sub.(x,y) and b.sub.l. The LSA protocol is modified to accommodate information used in determining whether a link is an impacted link.
Link Selection Schemes For Avoiding Channel Contention,
Tue Nov 29 16:06:39 EST 2011
A connection in an optical communication system is routed over a sequence of cross-connects and aggregated links comprising multiple links. A different link selection algorithm is used for service provisioning than is used for restoration, i.e., after a cable cut or other failure or incident has made one or paths in the network suddenly unavailable. In particular, a special link selection algorithm called the Interleave algorithm is used for restoration different from the well known Best-Fit algorithm used for provisioning. The Interleave algorithm substantially reduces the probability of glare while maintaining near-optimum capacity utilization.
Network Performance And Reliability Evaluation Taking Into Account Multiple Traffic Matrices,
Tue Aug 30 16:06:06 EDT 2011
Network performability characteristics with improved accuracy are derived by taking into account, in the various analyzed network failure states, attributes of elements at the logical level other than just the capacities of edges, as well as by taking into account one or more "abstract components," such as scheduled maintenance, and by using multiple traffic matrices.
Methods And Apparatus To Select Composite Link Cost-Out Thresholds,
Tue Jul 05 16:05:41 EDT 2011
Methods and apparatus to select composite link cost-out thresholds are disclosed. A disclosed example method comprises collecting traffic statistics for a communication network, computing, based on the collected traffic statistics, a plurality of flow rates for a composite link of the communication network for respective ones of a plurality of potential fault conditions for the composite link, computing a plurality of remaining capacities of the composite link for respective ones of the plurality of fault conditions, computing a plurality of differences between respective ones of the plurality of flow rates and the plurality of remaining capacities, and selecting a cost-out threshold for the composite link based on the plurality of computed differences.
Link selection schemes for avoiding channel contention,
Tue Nov 11 18:13:09 EST 2008
United States Patent: 7450516A connection in an optical communication system is routed over a sequence of cross-connects and aggregated links comprising multiple links. A different link selection algorithm is used for service provisioning than is used for restoration, i.e., after a cable cut or other failure or incident has made one or paths in the network suddenly unavailable. In particular, a special link selection algorithm called the Interleave algorithm is used for restoration different from the well known Best-Fit algorithm used for provisioning. The Interleave algorithm substantially reduces the probability of glare while maintaining near-optimum capacity utilization.
