Reaz Ahmed

A survey of naming and routing in information-centric networks

The concept of information-centric networking (ICN) defines a new communication model that focuses on what is being exchanged rather than which network entities are exchanging information. From the ICN perspective, contents are first class network citizens instead of hosts. ICNs primary objective is to shift the current host-oriented communication model toward a content-centric model for effective distribution of content over the network. In recent years this paradigm shift has generated much interest in the research community and sprung several research projects around the globe to investigate and advance this stream of thought. Content naming and content-based routing are core research challenges in this research community. In this survey, we analyze, compare, and contrast the naming and routing mechanisms proposed by some of the most prominent ICN research projects.

PayLess: A low cost network monitoring framework for Software Defined Networks

Software Defined Networking promises to simplify network management tasks by separating the control plane (a central controller) from the data plane (switches). OpenFlow has emerged as the de facto standard for communication between the controller and switches. Apart from providing flow control and communication interfaces, OpenFlow provides a flow level statistics collection mechanism from the data plane. It exposes a high level interface for per flow and aggregate statistics collection. Network applications can use this high level interface to monitor network status without being concerned about the low level details. In order to keep the switch design simple, this statistics collection mechanism is implemented as a pull-based service, i.e. network applications and in turn the controller has to periodically query the switches about flow statistics. The frequency of polling the switches determines monitoring accuracy and network overhead. In this paper, we focus on this trade-off between monitoring accuracy, timeliness and network overhead. We propose PayLess - a monitoring framework for SDN. PayLess provides a flexible RESTful API for flow statistics collection at different aggregation levels. It uses an adaptive statistics collection algorithm that delivers highly accurate information in real-time without incurring significant network overhead. We utilize the Floodlight controllers API to implement the proposed monitoring framework. The effectiveness of our solution is demonstrated through emulations in Mininet.

Dynamic Controller Provisioning in Software Defined Networks

Software Defined Networking (SDN) has emerged as a new paradigm that offers the programmability required to dynamically configure and control a network. A traditional SDN implementation relies on a logically centralized controller that runs the control plane. However, in a large-scale WAN deployment, this rudimentary centralized approach has several limitations related to performance and scalability. To address these issues, recent proposals have advocated deploying multiple controllers that work cooperatively to control a network. Nonetheless, this approach drags in an interesting problem, which we call the Dynamic Controller Provisioning Problem (DCPP). DCPP dynamically adapts the number of controllers and their locations with changing network conditions, in order to minimize flow setup time and communication overhead. In this paper, we propose a framework for deploying multiple controllers within an WAN. Our framework dynamically adjusts the number of active controllers and delegates each controller with a subset of Openflow switches according to network dynamics while ensuring minimal flow setup time and communication overhead. To this end, we formulate the optimal controller provisioning problem as an Integer Linear Program (ILP) and propose two heuristics to solve it. Simulation results show that our solution minimizes flow setup time while incurring very low communication overhead.

PolicyCop: An Autonomic QoS Policy Enforcement Framework for Software Defined Networks

Network management is becoming increasingly challenging with the relentless growth in network size, traffic volume, and the diversity in QoS requirements. Traditionally, the concept of predefined Service Level Agreements (SLAs) has been utilized to establish QoS parameters. However, most state-of-the-art technologies in this area are both proprietary and inflexible. To this end, Software Defined Networking (SDN) has the potential to make network management tasks flexible, scalable, and an open platform to encourage innovation. In this paper, we present the design of PolicyCop, an open, flexible, and vendor agnostic QoS policy management framework targeted towards OpenFlow based SDN. PolicyCop provides an interface for specifying QoS SLAs and then exploits the control planes API to enforce them. PolicyCop also monitors the network and autonomically readjusts network parameters to meet customer SLAs. We present experimental results to demonstrate PolicyCops effectiveness in ensuring throughput, latency, and reliability guarantees.

On orchestrating virtual network functions

Middleboxes or network appliances like firewalls, proxies, and WAN optimizers have become an integral part of todays ISP and enterprise networks. Middlebox functionalities are usually deployed on expensive and proprietary hardware that require trained personnel for deployment and maintenance. Middleboxes contribute significantly to a networks capital and operational costs. In addition, organizations often require their traffic to pass through a specific sequence of middleboxes for compliance with security and performance policies. This makes the middlebox deployment and maintenance tasks even more complicated. Network Function Virtualization (NFV) is an emerging and promising technology that is envisioned to overcome these challenges. It proposes to move packet processing from dedicated hardware middleboxes to software running on commodity servers. In NFV terminology, software middleboxes are referred to as Virtual Network Functions (VNFs). It is a challenging problem to determine the required number and placement of VNFs that optimize network operational costs and utilization, without violating service level agreements. We call this the VNF Orchestration Problem (VNF-OP) and provide an Integer Linear Programming (ILP) formulation with implementation in CPLEX. We also provide a dynamic programming based heuristic to solve larger instances of VNF-OP. Trace driven simulations on real-world network topologies demonstrate that the heuristic can provide solutions that are within 1.3 times of the optimal solution. Our experiments suggest that a VNF based approach can provide more than 4 χ reduction in the operational cost of a network.

Resource and service discovery in large-scale multi-domain networks

With the increasing need for networked applications and distributed resource sharing, there is a strong incentive for an open large-scale service infrastructure operating over multidomain and multi-technology networks. Service discovery, as an essential support function of such an infrastructure, is a crucial current research challenge. Although a few survey papers have been published on this subject, our contribution focuses on comparing and analyzing key discovery approaches in the context of large-scale and multidomain networks. The comparison is conducted based on a set of well-defined criteria, leading to a selection of few approaches that can serve as the guide in designing a global service discovery system for large-scale and multi-technology networks.

Design considerations for managing wide area software defined networks

SDN has the potential to simplify network configuration and reduce management complexity. In today¿s networks control and forwarding functions are tightly coupled and embedded within each switch/router. SDN, in contrast, accumulates the control functionality in one or more dedicated network entities called controllers, which provide a unified interface to configure and control the network. Packet forwarding, on the other hand, remains the responsibility of the switches/routers. Many datacenter networks have benefited from the abstraction provided by SDN. However, in a Wide Area Network (WAN) a single controller becomes a performance bottleneck. Multiple controller solutions are proposed as a natural consequence. In this article we present the requirements, design alternatives, and a possible management architecture for a single administrative domain WA-SDN. We also discuss the functional components that should be present in a multi-controller architecture for managing WA-SDN deployments.

Orchestrating Virtualized Network Functions

Middleboxes or network appliances like firewalls, proxies, and WAN optimizers have become an integral part of todays ISP and enterprise networks. Middlebox functionalities are usually deployed on expensive and proprietary hardware that require trained personnel for deployment and maintenance. Middleboxes contribute significantly to a networks capital and operation costs. In addition, organizations often require their traffic to pass through a specific sequence of middleboxes for compliance with security and performance policies. This makes the middlebox deployment and maintenance tasks even more complicated. Network function virtualization (NFV) is an emerging and promising technology that is envisioned to overcome these challenges. It proposes to move packet processing from dedicated hardware middleboxes to software running on commodity servers. In NFV terminology, software middleboxes are referred to as virtualized network functions (VNFs). It is a challenging problem to determine the required number and placement of VNFs that optimizes network operational costs and utilization, without violating service level agreements. We call this the VNF orchestration problem (VNF-OP) and provide an integer linear programming formulation with implementation in CPLEX. We also provide a dynamic programming-based heuristic to solve larger instances of VNF-OP. Trace driven simulations on realworld network topologies demonstrate that the heuristic can provide solutions that are within 1.3 times of the optimal solution. Our experiments suggest that a VNF-based approach can provide more than 4× reduction in the operational cost of a network.

Elastic virtual network function placement

Nowadays, many cloud providers offer Virtual Network Function (VNF) services that are dynamically scaled according to the workload. Enterprises enjoy these services by only paying for the actual consumed resources. From a cloud providers standpoint, the cost of these services must be kept as low as possible, while QoS is maintained and service downtime is minimized. In this paper, we introduce Elastic Virtual Network Function Placement (EVNFP) problem and present a model for minimizing operational costs in providing VNF services. In this model, the elasticity overhead and the trade-off between bandwidth and host resource consumption are considered together, while the previous works ignored this perspective of the problem. We propose a solution called Simple Lazy Facility Location (SLFL) that optimizes the placement of VNF instances in response to on-demand workload. Our experiments suggest that SLFL can accept two times more workload while incurring similar operational cost compared to first-fit and random placements.

Design and management of DOT: A Distributed OpenFlow Testbed

With the growing adoption of Software Defined Networking (SDN), there is a compelling need for SDN emulators that facilitate experimenting with new SDN-based technologies. Unfortunately, Mininet [1], the de facto standard emulator for software defined networks, fails to scale with network size and traffic volume. The aim of this paper is to fill the void in this space by presenting a low cost and scalable network emulator called Distributed OpenFlow Testbed (DOT). It can emulate large SDN deployments by distributing the workload over a cluster of compute nodes. Through extensive experiments, we show that DOT can overcome the limitations of Mininet and emulate larger networks. We also demonstrate the effectiveness of DOT on four Rocketfuel topologies. DOT is available for public use and community-driven development at dothub.org.