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A logical chaining of Virtual Network Functions (VNFs) enables toy-blocking style composition of various network services. VNFs are generally based on Virtual Machines (VMs) running on commodity servers. However, such VM-based VNFs have poor packet forwarding performance because of the virtual network I/O overhead, and therefore virtualization of the core network functions can degrade overall network...
The concept of network functions virtualization (NFV) has been embodied in commercial networks over the past years. Software-based virtual network functions have forwarding performance concerns in general, and various acceleration technologies have been developed so far, such as DPDK and vhost-user. Existence of several alternatives requires network engineers or operators to select appropriate technologies;...
Network Functions Virtualization (NFV) is now accepted in large production networks for agile introduction of various Network Functions (NFs). A service chaining technology that dynamically links multiple NFs over the entire network is a heart of the NFV concept. However, virtualizing NF-dedicated hardwares as virtual machines on IA servers brings performance problems, such as lower throughput, longer...
Network Functions Virtualization (NFV) has been expected to flexibly compose Virtual Network Functions (VNFs) by virtualizing existing network appliances and logically chaining them. Currently used VNFs are realized as VM-based appliances and shared by multiple users (VMs). However, the notion of NFV can be extended to reinforce network functionality of user VMs by introducing VM-dedicated VNFs. In...
Advanced public cloud datacenters have introduced an Edge-Overlay approach for multi-tenancy. This approach depends on L2-in-L3 tunneling protocols, however, existing protocols like VXLAN have performance problems. Stateless Transport Tunneling (STT) achieves high performance communications using offloading features, but STT has poor compatibility with existing network devices because of modified...
Overlay-based network virtualization has been getting attention to realize multi-tenant datacenters. But the multi-tenant property makes broadcast/multicast communications on virtual networks difficult. In this paper, we propose TE-Cast (Topology Embedded xCast) that supports generic broadcast/multicast communications on virtual networks. Unlike existing similar methods, TE-Cast can reduce traffic...
Many distributed systems use a replication mechanism for reliability and availability. On the other hand, developers have to consider minimum consistency requirement for each application. Therefore, a novel replication protocol that supports multiple consistency models is required. Multi-Consistency Data Replication (McRep) is a middleware-based replication protocol and can support multiple consistency...
The notion of Software-Defined Networking (SDN) has already been introduced into cloud datacenter networks for provisioning virtual network environment. Network virtualization of today is generally achieved by L2-in-L3 tunneling protocols like VXLAN (Virtual eXtensible LAN) and NVGRE (Network Virtualization using Generic Routing Encapsulation) in public cloud datacenters. Some leading production packages...
As the size of networks continues to increase, the scalability of the centralized controller becomes increasingly issues in Software Defined Networking. Distributed controllers have been proposed to solve the problem that the centralized controllers such as NOX and Floodlight suffer from. That logically centralized, but physically distributed architecture divide the network into zones with separate...
An Edge-Overlay model constructing virtual networks using both virtual switches and IP tunnels is promising in cloud datacenter networks. But software-implemented virtual switches can cause performance problems because the packet processing load is concentrated on a particular CPU core. Although multi queue functions like Receive Side Scaling (RSS) can distribute the load onto multiple CPU cores,...
Network Virtualization Overlays (NVO3) provides multi-tenancy services in cloud data centers with existing networking equipment. IP tunneling is an essential technology to logically separate each virtual traffic, in particular, Stateless Transport Tunneling (STT) is considered to achieve better performance using TCP Segmentation Offload (TSO) feature. Currently, there is no openly available implementation...
Network virtualization is an essential technology for cloud datacenters that provide multi-tenancy services. Cutting-edge SDN-enabled datacenters have introduced an edge-overlay (distributed tunneling) model to construct virtual tenant networks. The edge-overlay model generally uses L2-in-L3 tunneling protocols, and VXLAN is a representative of such protocols. However, the tunneling-based edge-overlay...
In current SDN paradigm, an edge-overlay (distributed tunneling) model using L2-in-L3 tunneling protocols, such as VXLAN, has attracted attentions for multi-tenant data center networks. The edge-overlay model can establish rapid-deployment of virtual networks onto existing traditional network facilities, ensure flexible IP/MAC address allocation to VMs, and extend the number of virtual networks regardless...
A management of large-scale data becomes more important, along with the spread of cloud service and the speed-up of networks. Since data management on a single machine can cause performance and scalability problems, data management across multiple machines has been proposed. Distributed Key Value Store(KVS) is a data store which manages data across multiple machines. Since distributed KVSs manage...
MapReduce is one of the major successful framework to process large-scale data efficiently. Distributed programs can be implemented easily by describing only two methods, Map and Reduce. In Hadoop which is an open source implementation of MapReduce, a Job Tracker (master program in Hadoop) assigns Map Tasks and Reduce Tasks to Task Trackers (slave programs which execute the tasks). In an environment...
A distributed file system is a scalable and reliable storage system. However, it has a problem that performance of the system is limited because a large number of metadata operations are concentrated in a single Metadata Server (MDS). To solve this problem, it is effective to cache metadata in client side memory but, consistency of the metadata cache needs to be guaranteed. There are mainly two methods...
Software-defined networks (SDN) has gradually been deployed on commercial networks such as datacenter networks. Current SDN is based on OpenFlow technology that is a set ofnetwork flow control API for switch devices. For instance, network reachability between end-hosts (or virtual machines), packet filtering mechanisms, and status management of switches are enabled by the API. In practice, however,...
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