Aman Shaikh

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Papers by Aman Shaikh

Design and implementation of a routing control platform

Networked Systems Design and Implementation, May 2, 2005

The routers in an Autonomous System (AS) must distribute the information they learn about how to ... more The routers in an Autonomous System (AS) must distribute the information they learn about how to reach external destinations. Unfortunately, today's internal Border Gateway Protocol (iBGP) architectures have serious problems: a "full mesh" iBGP configuration does not scale to large networks and "route reflection" can introduce problems such as protocol oscillations and persistent loops. Instead, we argue that a Routing Control Platform (RCP) should collect information about external destinations and internal topology and select the BGP routes for each router in an AS. RCP is a logicallycentralized platform, separate from the IP forwarding plane, that performs route selection on behalf of routers and communicates selected routes to the routers using the unmodified iBGP protocol. RCP provides scalability without sacrificing correctness. In this paper, we present the design and implementation of an RCP prototype on commodity hardware. Using traces of BGP and internal routing data from a Tier-1 backbone, we demonstrate that RCP is fast and reliable enough to drive the BGP routing decisions for a large network. We show that RCP assigns routes correctly, even when the functionality is replicated and distributed, and that networks using RCP can expect comparable convergence delays to those using today's iBGP architectures.

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Method and system for detecting common attributes of network upgrades

A system and method identify a set of rules for determining a commonality of attributes across di... more A system and method identify a set of rules for determining a commonality of attributes across different behavior changes for a network. The system performs the method by receiving a set of data correlating network triggers to performance changes of one or more network devices. The set of data further includes an indication of a sign of the performance change for each of the network devices based on the triggers. The method further includes extracting a set of rules relating to a set of relationships between the triggers and the performance changes. The rules identify a commonality of the performance changes for multiple network devices based on the triggers.

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Path inference in data center networks

Conference on Network and Service Management, Oct 22, 2012

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Advisor: R. K. Shyamasundar Thesis: Design and Implementation of Software Defined Radio PUBLICATIONS

RESEARCH INTERESTS • Systems and networks including design, management and security • Application... more

Analyzing the Hold Time Schemes to Limit the Routing Table Calculations in OSPF Protocol

2009 International Conference on Advanced Information Networking and Applications, 2009

OSPF is a popular interior gateway routing protocol. Commercial OSPF routers limit their processi... more OSPF is a popular interior gateway routing protocol. Commercial OSPF routers limit their processing load by using a hold time between successive routing table calculations as new link state advertisements (LSAs) arrive following a topology change. A large hold time value limits the frequency of routing table calculations but also causes large delays in convergence to the topology change. Hence,

Placing Relay Nodes for Intra-Domain Path Diversity

Proceedings IEEE INFOCOM 2006. 25TH IEEE International Conference on Computer Communications, 2006

‡ Chong-Dae Park is supported by Brain Korea 21 (BK21) project through the school of information ... more

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On the Resiliency of Virtual Network Functions

IEEE Communications Magazine, 2017

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Libra: Impact assessment of cellular load balancing

IEEE INFOCOM 2016 - The 35th Annual IEEE International Conference on Computer Communications, 2016

Load on cellular towers is one of the key metrics that cellular service providers monitor as part... more Load on cellular towers is one of the key metrics that cellular service providers monitor as part of their operational and management tasks. Increased load on the towers can lead to congestion, which in turn can severely degrade quality of service perceived by users. Hence, it is of great interest to cellular service providers to minimize the maximum load at cell towers, and thereby minimize chances of congestion in the event of a sudden increase in load due to user demand changes. This goal can be achieved by proactive load balancing among neighboring cell towers, i.e., proactively identify opportunities to balance the load through re-binding of users from heavily loaded cell towers to lightly loaded neighboring towers. In this paper, we propose a new tool Libra to effectively assess the impact of load balancing related parameter changes. Libra provides an objective measure of the degree of load imbalance across multiple network locations and identifies if the measure improves or degrades after parameter changes. Our evaluation of Libra using real-world data collected from a large cellular provider demonstrates its effectiveness in accurately capturing the degree of imbalance at multiple cell towers.

Positioning Relay Nodes in ISP Network

To increase reliability and robustness of mission-critical services in the event of network failu... more To increase reliability and robustness of mission-critical services in the event of network failures, it is often desirable and beneficial to take advantage of path diversity provided by the network topology. One way of achieving this inside a single Autonomous System (AS) is to use two paths between every Origin-Destination (OD) pair. One path is the default path defined by the intra-domain routing protocol running within the AS; the other path is defined as an overlay path that passes through a strategically placed relay node inside the AS. The key question then is how to place such relay nodes inside an AS, which is the focus of this work. We propose a simple greedy algorithm to find the number and positions of relay nodes such that every OD pair has an overlay path going through a relay node that is disjoint from the default path. When it is not possible to find completely disjoint overlay paths, we allow overlay paths to have overlapped links with default paths. Since overlapped links diminish the robustness of overlay paths against a single point of failure, we introduce the notion of penalty for partially disjoint paths. We apply our algorithm on an operational tier-1 ISP network and demonstrate that our method increases network-wide resiliency against a single link failure. Based on real failure scenarios obtained from the ISP network and hypothetical traffic matrix, we demonstrate that the relay nodes selected by our algorithm provide complete protection against 75.3% of failure events and allow less than 1% of traffic to be affected for 92.8% of failure events. †These authors are supported by Korea Science and Engineering Foundation (KOSEF) through Advanced Information Technology Research Center (AITrc). ‡This author is supported by Brain Korea (BK) 21 Project and the school of information technology in KAIST.

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Method, apparatus and computer readable medium storing a software program for selecting routes to be distributed within networks

TowardsAutomatedPerformanceDiagnosisinaLarge

In the past several years, IPTV has been rapidly deployed and offered as a commercial service to ... more In the past several years, IPTV has been rapidly deployed and offered as a commercial service to residential broadband customers. Compared to traditional ISP networks, IPTV distribution network typically adopts a different structure (tree-like multicast as opposed to mesh), imposes more restrictive service constraints (both in reliability and performance), has different traffic patterns and distribution protocols (multicast versus unicast), and often faces a much larger scalability issue (managing millions of residential gateways versus thousands of provider-edge routers). All of these pose tremendous challenges in the effective management of IPTV network and service. In this paper, we focus on characterizing and troubleshooting faults and performance impairments in one of the largest IPTV providers in North America. We collect massive amounts of measurement data both in provider network and residential part of the IPTV network, ranging from device usage / error logs, user activity ...

Considerations When Using Basic OSPF Convergence Benchmarks

This document discusses the applicability of various tests for measuring single router control pl... more This document discusses the applicability of various tests for measuring single router control plane convergence, specifically in regard to the Open Shortest First (OSPF) protocol. There are two general sections in this document, the first discusses advantages and limitations of specific OSPF convergence tests, and the second discusses more general pitfalls to be considered when routing protocol convergence is tested. Manral, et al.

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Quantifying the Extent of IPv6 Deployment

Lecture Notes in Computer Science, 2009

Our understanding of IPv6 deployment is surprisingly limited. In fact, it is not even clear how w... more Our understanding of IPv6 deployment is surprisingly limited. In fact, it is not even clear how we should quantify IPv6 deployment. In this paper, we collect and analyze a variety of data to characterize the penetration of IPv6. We show that each analysis leads to somewhat different conclusions. For example: registry data shows IPv6 address allocations are growing rapidly, yet BGP table dumps indicate many addresses are either never announced or announced long after allocation; Netflow records from a tier-1 ISP show growth in native IPv6 traffic, but deeper analysis reveals most of the traffic is DNS queries and ICMP packets; a more detailed inspection of tunneled IPv6 traffic uncovers many packets exchanged between IPv4-speaking hosts (e.g., to traverse NAT boxes). Overall, our study suggests that from our vantage points, current IPv6 deployment appears somewhat experimental, and that the growth of IPv6 allocations, routing announcements, and traffic volume probably indicate more operators and users preparing themselves for the transition to IPv6.

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Integer Linear Programs for Routing and Protection Problems in Optical Networks

Encyclopedia of Optimization

Impact of prefix-match changes on IP reachability

Proceedings of the 9th ACM SIGCOMM conference on Internet measurement conference - IMC '09, 2009

Although most studies of Internet routing treat each IP address block (or prefix) independently, ... more Although most studies of Internet routing treat each IP address block (or prefix) independently, the relationship between prefixes is important because routers ultimately forward packets based on the "longest-matching prefix." In fact, the most-specific prefix for a given destination address may change over time, as BGP routes are announced and withdrawn. Even if the most-specific route is withdrawn, routers may still be able to deliver packets to the destination using a less-specific route. In this paper, we analyze BGP update messages and Netflow traffic traces from a large ISP to characterize both the changes to the longest-matching prefix over time and the resulting effects on end-to-end reachability of the destination hosts. To drive our analysis, we design and implement an efficient online algorithm for tracking changes in the longest-matching prefix for each IP address. We analyze the BGP message traces to identify the reasons for prefix-match changes, including failures, route flapping, sub-prefix hijacking, and load-balancing policies. Our preliminary analysis of the Netflow data suggests that the relationship between BGP updates and IP reachability is sometimes counterintuitive.

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Route oracle

ACM SIGMETRICS Performance Evaluation Review, 2010

Many network-management problems in large backbone networks need the answer to a seemingly simple... more Many network-management problems in large backbone networks need the answer to a seemingly simple question: where does a given IP packet, entering the network at a particular place and time, leave the network to continue on its path to the destination? Answering this question at scale and in real time is challenging for several reasons: (i) a destination IP address could match several IP prefixes, (ii) the longest-matching prefix may change over time, (iii) the number of IP prefixes and routing protocol messages is very large, and (iv) network-management applications often require answers to this question for a large number of destination IP addresses in real time. In this paper, we present an efficient algorithm for tracking prefix-match changes for ranges of IP addresses. We then present the design, implementation, and evaluation of the Route Oracle tool that answers queries about routing changes on behalf of network management applications. Our design of Route Oracle includes sev...

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Experience in black-box OSPF measurement

Proceedings of the First ACM SIGCOMM Workshop on Internet Measurement - IMW '01, 2001

OSPF (Open Shortest Path First) is a widely used intra-domain routing protocol in IP networks. In... more OSPF (Open Shortest Path First) is a widely used intra-domain routing protocol in IP networks. Internal processing delays in OSPF implementations impact the speed at which updates propagate in the network, the load on individual routers, and the time needed for both intradomain and inter-domain routing to reconverge following an internal topology or a configuration change. An OSPF user, such as an Internet Service Provider, typically has no access to the software implementation, and no way to estimate these delays directly. In this paper, we present blackbox methods (i.e., measurements that rely only on external observations) for estimating and trending delays for key internal tasks in OSPF: processing Link State Advertisements (LSAs), performing Shortest Path First calculations, updating the Forwarding Information Base, and flooding LSAs. Corresponding measurements are reported for production routers from Cisco Systems. To help validate the methodology, black-box and white-box (i.e., measurements that rely on internal instrumentation) are reported for a open source OSPF implementation, GateD.

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Method and apparatus for generating a set of aggregates

Methods and apparatus to analyze autonomous system peering policies

Peering Dragnet: anti-social behavior amongst peers, and what you can do about it

Aman Shaikh

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