28,628 research outputs found
Service Chain (SC) Mapping with Multiple SC Instances in a Wide Area Network
Network Function Virtualization (NFV) aims to simplify deployment of network
services by running Virtual Network Functions (VNFs) on commercial
off-the-shelf servers. Service deployment involves placement of VNFs and
in-sequence routing of traffic flows through VNFs comprising a Service Chain
(SC). The joint VNF placement and traffic routing is usually referred as SC
mapping. In a Wide Area Network (WAN), a situation may arise where several
traffic flows, generated by many distributed node pairs, require the same SC,
one single instance (or occurrence) of that SC might not be enough. SC mapping
with multiple SC instances for the same SC turns out to be a very complex
problem, since the sequential traversal of VNFs has to be maintained while
accounting for traffic flows in various directions. Our study is the first to
deal with SC mapping with multiple SC instances to minimize network resource
consumption. Exact mathematical modeling of this problem results in a quadratic
formulation. We propose a two-phase column-generation-based model and solution
in order to get results over large network topologies within reasonable
computational times. Using such an approach, we observe that an appropriate
choice of only a small set of SC instances can lead to solution very close to
the minimum bandwidth consumption
A Scalable Approach for Service Chain (SC) Mapping with Multiple SC Instances in a Wide-Area Network
Network Function Virtualization (NFV) aims to simplify deployment of network
services by running Virtual Network Functions (VNFs) on commercial
off-the-shelf servers. Service deployment involves placement of VNFs and
in-sequence routing of traffic flows through VNFs comprising a Service Chain
(SC). The joint VNF placement and traffic routing is called SC mapping. In a
Wide-Area Network (WAN), a situation may arise where several traffic flows,
generated by many distributed node pairs, require the same SC; then, a single
instance (or occurrence) of that SC might not be enough. SC mapping with
multiple SC instances for the same SC turns out to be a very complex problem,
since the sequential traversal of VNFs has to be maintained while accounting
for traffic flows in various directions. Our study is the first to deal with
the problem of SC mapping with multiple SC instances to minimize network
resource consumption. We first propose an Integer Linear Program (ILP) to solve
this problem. Since ILP does not scale to large networks, we develop a
column-generation-based ILP (CG-ILP) model. However, we find that exact
mathematical modeling of the problem results in quadratic constraints in our
CG-ILP. The quadratic constraints are made linear but even the scalability of
CG-ILP is limited. Hence, we also propose a two-phase column-generation-based
approach to get results over large network topologies within reasonable
computational times. Using such an approach, we observe that an appropriate
choice of only a small set of SC instances can lead to a solution very close to
the minimum bandwidth consumption. Further, this approach also helps us to
analyze the effects of number of VNF replicas and number of NFV nodes on
bandwidth consumption when deploying these minimum number of SC instances.Comment: arXiv admin note: substantial text overlap with arXiv:1704.0671
2021 International Conference on Optical Network Design and Modeling (ONDM)
Producción CientíficaThe planning of multi-access edge computing (MEC) systems does not only consist in distributing MEC servers among the base stations (BSs) but also in designing the network to interconnect BSs, MEC resources and the wide area network (WAN) gateway. Due to their high bandwidth, fiber links are the best option for those connections in 5G environments. In contrast to previous works, which only solve the server placement problem, in this paper, an integer linear programming (ILP) formulation is proposed for solving both problems while reducing the installation cost (servers and fibers). The fiber deployment cost is especially important in sparsely populated areas as the distance between BSs are much longer than in urban environments. The model was tested using real BSs locations and population data showing that the formulation considerably reduces the installation cost.Interreg V-A Spain-Portugal (POCTEP) programme 2014- 2020 (project 0667_DISRUPTIVE_2_E)Ministerio de Economía, Industria y Competitividad (projects TEC2017-84423-C3-1-P and RED2018- 102585-T)Junta de Castilla y León - Fondo Europeo de Desarrollo Regional (project VA231P20
Traffic-Aware Deployment of Interdependent NFV Middleboxes in Software-Defined Networks
Middleboxes, such as firewalls, Network Address Translators (NATs), Wide Area Network (WAN) optimizers, or Deep Packet Inspector (DPIs), are widely deployed in modern networks to improve network security and performance. Traditional middleboxes are typically hardware based, which are expensive and closed systems with little extensibility. Furthermore, they are developed by different vendors and deployed as standalone devices with little scalability. As the development of networks in scale, the limitations of traditional middleboxes bring great challenges in middlebox deployments.
Network Function Virtualization (NFV) technology provides a promising alternative, which enables flexible deployment of middleboxes, as virtual machines (VMs) running on standard servers. However, the flexibility also creates a challenge for efficiently placing such middleboxes, due to the availability of multiple hosting servers, capabilities of middleboxes to change traffic volumes, and dependency between middleboxes. In our first two work, we addressed the optimal placement challenge of NFV middleboxes by considering middlebox traffic changing effects and dependency relations. Since each VM has only a limited processing capacity restricted by its available resources, multiple instances of the same function are necessary in an NFV network. Thus, routing in an NFV network is also a challenge to determine not only via a path from the source to destination but also the service (middlebox) locations. Furthermore, the challenge is complicated by the traffic changing effects of NFV services and dependency relations between them. In our third work, we studied how to efficiently route a flow to receive services in an NFV network.
We conducted large-scale simulations to evaluate our proposed solutions, and also implemented a Software-Defined Networking (SDN) based prototype to validate the solutions in realistic environments. Extensive simulation and experiment results have been fully demonstrated the effectiveness of our design
Supporting distributed computation over wide area gigabit networks
The advent of high bandwidth fibre optic links that may be used over very large distances
has lead to much research and development in the field of wide area gigabit networking. One
problem that needs to be addressed is how loosely coupled distributed systems may be built over
these links, allowing many computers worldwide to take part in complex calculations in order
to solve "Grand Challenge" problems. The research conducted as part of this PhD has looked
at the practicality of implementing a communication mechanism proposed by Craig Partridge
called Late-binding Remote Procedure Calls (LbRPC).
LbRPC is intended to export both code and data over the network to remote machines for
evaluation, as opposed to traditional RPC mechanisms that only send parameters to pre-existing
remote procedures. The ability to send code as well as data means that LbRPC requests can
overcome one of the biggest problems in Wide Area Distributed Computer Systems (WADCS):
the fixed latency due to the speed of light. As machines get faster, the fixed multi-millisecond
round trip delay equates to ever increasing numbers of CPU cycles. For a WADCS to be
efficient, programs should minimise the number of network transits they incur. By allowing the
application programmer to export arbitrary code to the remote machine, this may be achieved.
This research has looked at the feasibility of supporting secure exportation of arbitrary
code and data in heterogeneous, loosely coupled, distributed computing environments. It has
investigated techniques for making placement decisions for the code in cases where there are a
large number of widely dispersed remote servers that could be used. The latter has resulted in
the development of a novel prototype LbRPC using multicast IP for implicit placement and a
sequenced, multi-packet saturation multicast transport protocol. These prototypes show that
it is possible to export code and data to multiple remote hosts, thereby removing the need to
perform complex and error prone explicit process placement decisions
Dynamic, Latency-Optimal vNF Placement at the Network Edge
Future networks are expected to support low-latency, context-aware and user-specific services in a highly flexible and efficient manner. One approach to support emerging use cases such as, e.g., virtual reality and in-network image processing is to introduce virtualized network functions (vNF)s at the edge of the network, placed in close proximity to the end users to reduce end-to-end latency, time-to-response, and unnecessary utilisation in the core network. While placement of vNFs has been studied before, it has so far mostly focused on reducing the utilisation of server resources (i.e., minimising the number of servers required in the network to run a specific set of vNFs), and not taking network conditions into consideration such as, e.g., end-to-end latency, the constantly changing network dynamics, or user mobility patterns. In this paper, we formulate the Edge vNF placement problem to allocate vNFs to a distributed edge infrastructure, minimising end-to-end latency from all users to their associated vNFs. We present a way to dynamically re-schedule the optimal placement of vNFs based on temporal network-wide latency fluctuations using optimal stopping theory. We then evaluate our dynamic scheduler over a simulated nation-wide backbone network using real-world ISP latency characteristics. We show that our proposed dynamic placement scheduler minimises vNF migrations compared to other schedulers (e.g., periodic and always-on scheduling of a new placement), and offers Quality of Service guarantees by not exceeding a maximum number of latency violations that can be tolerated by certain applications
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