In this paper, we empirically demonstrate the growing importance of reliability by measuring its effect on user behavior. We present an approach for broadband reliability characterization using data collected by many emerging national initiatives to study broadband and apply it to the data gathered by the Federal Communications Commission's Measuring Broadband America project. Motivated by our findings, we present the design, implementation, and evaluation of a practical approach for improving the reliability of broadband Internet access with multihoming.
Beyond improvements in access link technology, one way to enhance the reliability of access networks is through redundancy. @cite_24 propose a detouring approach to recover from Internet path failures. improved web availability with their system, MONET, an overlay network of multihomed proxy servers @cite_1 . We have seen the recent introduction of consumer-grade residential gateways that support a second WAN connection (such as a 3G or 4G modem) @cite_52 and some work exploring the performance benefits of the on-loading of broadband traffic using a 3G connection @cite_30 . Det presented MiMBox, a system for translating between TCP and MPTCP connections at the middlebox @cite_3 . Other works have explored the benefits of using MPTCP on mobile devices @cite_12 @cite_34 and the possibility of bonding multiple access links (such as DSL and cable) to increase performance @cite_16 @cite_54 @cite_19 .
@cite_30 @cite_54 @cite_1 @cite_52 @cite_3 @cite_16 @cite_24 @cite_19 @cite_34 @cite_12
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Multipath TCP (MPTCP) is a major modification to TCP that enables a single transport connection to use multiple paths. Smartphones can benefit from MPTCP by using both WiFi and 3G 4G interfaces for their data-traffic, potentially improving the performance and allowing mobility through vertical handover. However, MPTCP requires a modification of the end hosts, thus suffers from the chicken-and-egg deployment problem. A global deployment of MPTCP is therefore expected to take years. To increase the incentives for clients and servers to upgrade their system, we propose MiMBox an efficient protocol converter that can translate MPTCP into TCP and vice versa to provide multipath benefits to early adopters of MPTCP. MiMBox is application agnostic and can be used transparently or explicitly. Moreover, a close attention was paid to the implementation's design to achieve good forwarding performance. MiMBox is implemented entirely in the Linux kernel so that it is able to more easily circumvent the bottlenecks of a user-space implementation. Measurements show that we always outperform user-space solutions and that the performance is close to plain IP packet forwarding. Despite the increasing degree of multi-homing, path and data redundancy, and capacity available in the Internet, today's clients experience outage rates of a few percent when accessing Web sites. MONET ("Multi-homed Overlay NETwork), is a new system that improves client availability to Web sites using a combination of link multi-homing and a cooperative overlay network of peer proxies to obtain a diverse collection of paths between clients and Web sites. This approach creates many potential paths between clients and Web sites, requiring a scalable way to selecting a good path. MONET solves this problem using a waypoint selection algorithm, which picks a good small subset of all available paths to actively probe. MONET runs on FreeBSD, Linux, and Mac OS X, and is deployed at six different sites. These installations have been running MONET for over one year, serving about fifty users on a daily basis. Our analysis of proxy traces shows that the proxy network avoids between 60 and 94 of observed failures, including access link failures, Internet routing problems, persistent path congestion, and DNS failures. The proxy avoids nearly 100 of failures due to client and wide-area network failures, with negligible overhead. Recent advances in signal processing have demonstrated in-band full-duplex capability at WiFi ranges. In addition to simultaneous two-way exchange between two nodes, full-duplex access points can potentially support simultaneous uplink and downlink flows. However, the atomic three-node topology, which allows simultaneous uplink and downlink, leads to inter-client interference. In this paper, we propose a random-access medium access control protocol using distributed power control to manage inter-client interference in wireless networks with full-duplex-capable access points that serve half-duplex clients. Our key contributions are two-fold. First, we identify the regimes in which power control provides sum throughput gains for the three-node atomic topology, with one uplink flow and one downlink flow. Second, we develop and benchmark PoCMAC, a full 802.11-based protocol that allows distributed selection of a three-node topology. The proposed MAC protocol is shown to achieve higher capacity as compared to an equivalent half-duplex counterpart, while maintaining similar fairness characteristics in single contention domain networks. We carried out extensive simulations and software-defined radio-based experiments to evaluate the performance of the proposed MAC protocol, which is shown to achieve a significant improvement over its half-duplex counterpart in terms of throughput performance. The latest large-scale data centers offer higher aggregate bandwidth and robustness by creating multiple paths in the core of the net- work. To utilize this bandwidth requires different flows take different paths, which poses a challenge. In short, a single-path transport seems ill-suited to such networks. We propose using Multipath TCP as a replacement for TCP in such data centers, as it can effectively and seamlessly use available bandwidth, giving improved throughput and better fairness on many topologies. We investigate what causes these benefits, teasing apart the contribution of each of the mechanisms used by MPTCP. Using MPTCP lets us rethink data center networks, with a different mindset as to the relationship between transport protocols, rout- ing and topology. MPTCP enables topologies that single path TCP cannot utilize. As a proof-of-concept, we present a dual-homed variant of the FatTree topology. With MPTCP, this outperforms FatTree for a wide range of workloads, but costs the same. In existing data centers, MPTCP is readily deployable leveraging widely deployed technologies such as ECMP. We have run MPTCP on Amazon EC2 and found that it outperforms TCP by a factor of three when there is path diversity. But the biggest benefits will come when data centers are designed for multipath transports. In this paper, we present an experiment- and simulation-based study to evaluate the use of full duplex (FD) as a potential mode in practical IEEE 802.11 networks. To enable the study, we designed a 20-MHz multiantenna orthogonal frequency-division-multiplexing (OFDM) FD physical layer and an FD media access control (MAC) protocol, which is backward compatible with current 802.11. Our extensive over-the-air experiments, simulations, and analysis demonstrate the following two results. First, the use of multiple antennas at the physical layer leads to a higher ergodic throughput than its hardware-equivalent multiantenna half-duplex (HD) counterparts for SNRs above the median SNR encountered in practical WiFi deployments. Second, the proposed MAC translates the physical layer rate gain into near doubling of throughput for multinode single-AP networks. The two results allow us to conclude that there are potentially significant benefits gained from including an FD mode in future WiFi standards. In conventional Wireless Mesh Networks (WMNs), multihop relays are performed in the backbone comprising of interconnected Mesh Routers (MRs) and this causes capacity degradation. This paper proposes a hybrid WMN architecture that the backbone is able to utilize random connections to Access Points (APs) of Wireless Local Area Network (WLAN). In such a proposed hierarchal architecture, capacity enhancement can be achieved by letting the traffic take advantage of the wired connections through APs. Theoretical analysis has been conducted for the asymptotic capacity of three-tier hybrid WMN, where per-MR capacity in the backbone is first derived and per-MC capacity is then obtained. Besides related to the number of MR cells as a conventional WMN, the analytical results reveal that the asymptotic capacity of a hybrid WMN is also strongly affected by the number of cells having AP connections, the ratio of access link bandwidth to backbone link bandwidth, etc. Appropriate configuration of the network can drastically improve the network capacity in our proposed network architecture. It also shows that the traffic balance among the MRs with AP access is very important to have a tighter asymptotic capacity bound. The results and conclusions justify the perspective of having such a hybrid WMN utilizing widely deployed WLANs. In theory, multi homed Internet hosts, that is, hosts simultaneously connected to multiple Internet service providers (ISP) should see increased access capacity, be able to circumvent possible last-mile congestion problems, and experience improved end-to-end quality of service (QoS). In practice however, the advantages one can gain from multi homing are highly dependent on the path switching mechanism used, that is, on dynamically deciding which ISP should be used as a first-hop. This paper is a first step toward understanding the trade-off between performance improvements multi homing can help achieve and the complexity of the decisions that must be made. We measure changes in end-to-end network layer metrics (loss, latency, jitter) over the different paths available from a multi homed host to a large population of Internet hosts. Our measurements indicate that (1) in over 60 of the cases, one only needs to reevaluate the service provided by each ISP every minute to improve the performance of a specific metric, and that (2) in approximately 85 of the cases, decisions to switch from one ISP to another can be treated independently of the service metric of interest. We conclude that multi homing could in practice result in noticeable performance improvements. Datacenter networks provide high path diversity for traffic between machines. Load balancing traffic across these paths is important for both, latency- and throughput-sensitive applications. The standard load balancing techniques used today obliviously hash a flow to a random path. When long flows collide on the same path, this might lead to long lasting congestion while other paths could be underutilized, degrading performance of other flows as well. Recent proposals to address this shortcoming incur significant implementation complexity at the host that would actually slow down short flows (MPTCP), depend on relatively slow centralized controllers for rerouting large congesting flows (Hedera), or require custom switch hardware, hindering near-term deployment (DeTail). We propose FlowBender, a novel technique that: (1) Load balances distributively at the granularity of flows instead of packets, avoiding excessive packet reordering. (2) Uses end-host-driven rehashing to trigger dynamic flow-to-path assignment. (3) Recovers from link failures within a Retransmit Timeout (RTO). (4) Amounts to less than 50 lines of critical kernel code and is readily deployable in commodity data centers today. (5) Is very robust and simple to tune. We evaluate FlowBender using both simulations and a real testbed implementation, and show that it improves average and tail latencies significantly compared to state of the art techniques without incurring the significant overhead and complexity of other load balancing schemes. Continuously enriched distributed systems in data centers generate much network traffic in push-style one-to-many group mode, raising new requirements for multicast transport in terms of efficiency and robustness. Existing reliable multicast solutions, which suffer from low robustness and inefficiency in either host-side protocols or multicast routing, are not suitable for data centers. In order to address the problems of inefficiency and low robustness, we present a sender-initiated, efficient, congestion-aware and robust reliable multicast solution mainly for small groups in SDN-based data centers, called MCTCP. The main idea behind MCTCP is to manage the multicast groups in a centralized manner, and reactively schedule multicast flows to active and low-utilized links, by extending TCP as the host-side protocol and managing multicast groups in the SDN-controller. The multicast spanning trees are calculated and adjusted according to the network status to perform a better allocation of resources. Our experiments show that, MCTCP can dynamically bypass the congested and failing links, achieving high efficiency and robustness. As a result, MCTCP outperforms the state-of-the-art reliable multicast schemes. Moreover, MCTCP improves the performance of data replication in HDFS compared with the original and TCP-SMO based ones, e.g., achieves 101 and 50 improvements in terms of bandwidth, respectively. In wireless ad hoc networks (WANets), multihop routing may result in a radio knowing the content of transmissions of nearby radios. This knowledge can be used to improve spatial reuse in the network, thereby enhancing network throughput. Consider two radios, Alice and Bob, that are neighbors in a WANet not employing spread-spectrum multiple access. Suppose that Alice transmits a packet to Bob for which Bob is not the final destination. Later, Bob forwards that packet on to the destination. Any transmission by Bob not intended for Alice usually causes interference that prevents Alice from receiving a packet from any of her neighbors. However, if Bob is transmitting a packet that he previously received from Alice, then Alice knows the content of the interfering packet, and this knowledge can allow Alice to receive a packet from one of her neighbors during Bob's transmission. In this paper, we develop overlapped transmission techniques based on this idea and analyze several factors affecting their performance. We then develop a MAC protocol based on the IEEE 802.11 standard to support overlapped transmission in a WANet. The resulting overlapped CSMA (OCSMA) protocol improves spatial reuse and end-to-end throughput in several scenarios.