1,224 research outputs found
A Multi-perspective Analysis of Carrier-Grade NAT Deployment
As ISPs face IPv4 address scarcity they increasingly turn to network address
translation (NAT) to accommodate the address needs of their customers.
Recently, ISPs have moved beyond employing NATs only directly at individual
customers and instead begun deploying Carrier-Grade NATs (CGNs) to apply
address translation to many independent and disparate endpoints spanning
physical locations, a phenomenon that so far has received little in the way of
empirical assessment. In this work we present a broad and systematic study of
the deployment and behavior of these middleboxes. We develop a methodology to
detect the existence of hosts behind CGNs by extracting non-routable IP
addresses from peer lists we obtain by crawling the BitTorrent DHT. We
complement this approach with improvements to our Netalyzr troubleshooting
service, enabling us to determine a range of indicators of CGN presence as well
as detailed insights into key properties of CGNs. Combining the two data
sources we illustrate the scope of CGN deployment on today's Internet, and
report on characteristics of commonly deployed CGNs and their effect on end
users
Multi-homing tunnel broker
A proper support for communications has to provide fault tolerance capabilities such as the preservation of established connections in case of failures. Multihoming addresses this issue, but the currently available solution based in massive BGP route injection presents serious scalability limitations, since it contributes to the exponential growth of the BGP table size. An alternative solution based on the configuration of tunnels between the multihomed site exit routers and the ISP border routers has been proposed for IPv6 in RFC 3178. However, the amount of manual configuration imposed by this solution on the ISP side prevents its wide adoption. In particular, this solution requires at the ISP the manual configuration of a tunnel endpoint per each multihomed client that it serves. We present a multihoming tunnel broker (MHTB) that provides automatic creation of the tunnel endpoint at the ISP side.This work was supported by the SAM (Advanced Servers with Mobility)project, funded by the Spanish National research and Development Programme as TIC2002-04531-C04-03.Publicad
Description and Experience of the Clinical Testbeds
This deliverable describes the up-to-date technical environment at three clinical testbed demonstrator sites of
the 6WINIT Project, including the adapted clinical applications, project components and network transition technologies
in use at these sites after 18 months of the Project. It also provides an interim description of early experiences with
deployment and usage of these applications, components and technologies, and their clinical service impact
A Survey on Handover Management in Mobility Architectures
This work presents a comprehensive and structured taxonomy of available
techniques for managing the handover process in mobility architectures.
Representative works from the existing literature have been divided into
appropriate categories, based on their ability to support horizontal handovers,
vertical handovers and multihoming. We describe approaches designed to work on
the current Internet (i.e. IPv4-based networks), as well as those that have
been devised for the "future" Internet (e.g. IPv6-based networks and
extensions). Quantitative measures and qualitative indicators are also
presented and used to evaluate and compare the examined approaches. This
critical review provides some valuable guidelines and suggestions for designing
and developing mobility architectures, including some practical expedients
(e.g. those required in the current Internet environment), aimed to cope with
the presence of NAT/firewalls and to provide support to legacy systems and
several communication protocols working at the application layer
IPv4 address sharing mechanism classification and tradeoff analysis
The growth of the Internet has made IPv4 addresses a scarce resource. Due to slow IPv6 deployment, IANA-level IPv4 address exhaustion was reached before the world could transition to an IPv6-only Internet. The continuing need for IPv4 reachability will only be supported by IPv4 address sharing. This paper reviews ISP-level address sharing mechanisms, which allow Internet service providers to connect multiple customers who share a single IPv4 address. Some mechanisms come with severe and unpredicted consequences, and all of them come with tradeoffs. We propose a novel classification, which we apply to existing mechanisms such as NAT444 and DS-Lite and proposals such as 4rd, MAP, etc. Our tradeoff analysis reveals insights into many problems including: abuse attribution, performance degradation, address and port usage efficiency, direct intercustomer communication, and availability
FAIR: Forwarding Accountability for Internet Reputability
This paper presents FAIR, a forwarding accountability mechanism that
incentivizes ISPs to apply stricter security policies to their customers. The
Autonomous System (AS) of the receiver specifies a traffic profile that the
sender AS must adhere to. Transit ASes on the path mark packets. In case of
traffic profile violations, the marked packets are used as a proof of
misbehavior.
FAIR introduces low bandwidth overhead and requires no per-packet and no
per-flow state for forwarding. We describe integration with IP and demonstrate
a software switch running on commodity hardware that can switch packets at a
line rate of 120 Gbps, and can forward 140M minimum-sized packets per second,
limited by the hardware I/O subsystem.
Moreover, this paper proposes a "suspicious bit" for packet headers - an
application that builds on top of FAIR's proofs of misbehavior and flags
packets to warn other entities in the network.Comment: 16 pages, 12 figure
A Demonstration Scenario for the NorNet Core Multi-Homed Network Testbed
There is extensive on-going research taking place with the goal of implementing transport layer protocols that are able to utilize multi-homing on machines (connection to multiple ISPs). Multi-homing has potential to improve resilience and increase total goodput compared to using a single connection. This would e.g. benefit the trend of more and more services being moved online and into the cloud. The NorNet Core multi-homed network testbed aims to facilitate this research by offering programmable virtual machines located at multiple different sites across the world, accessible for researchers. The aim of this project is the design and implementation of a demonstration platform for NorNet Core that enables the testbed to be illustratively demonstrated to potential new users. This is done by offering users interactive experiments, and geographical visualization of various communication scenarios between nodes in the NorNet Core network in real time. The demonstration platform puts emphasis on demonstrating the unique aspects of NorNet Core compared to other networking testbeds; namely the multi-homed nature and IPv6 support for all of the nodes. This thesis discusses the technical aspects of designing and implementing the platform, as well as demonstrating the finished result with various demonstration scenarios. The Qt programming framework was chosen as the primary development framework for this application
Use of locator/identifier separation to improve the future internet routing system
The Internet evolved from its early days of being a small research network to become a critical infrastructure many organizations and individuals rely on. One dimension of this evolution is the continuous growth of the number of participants in the network, far beyond what the initial designers had in mind. While it does work today, it is widely believed that the current design of the global routing system cannot scale to accommodate future challenges.
In 2006 an Internet Architecture Board (IAB) workshop was held to develop a shared understanding of the Internet routing system scalability issues faced by the large backbone operators. The participants documented in RFC 4984 their belief that "routing scalability is the most important problem facing the Internet today and must be solved."
A potential solution to the routing scalability problem is ending the semantic overloading of Internet addresses, by separating node location from identity. Several proposals exist to apply this idea to current Internet addressing, among which the Locator/Identifier Separation Protocol (LISP) is the only one already being shipped in production routers. Separating locators from identifiers results in another level of indirection, and introduces a new problem: how to determine location, when the identity is known.
The first part of our work analyzes existing proposals for systems that map identifiers to locators and proposes an alternative system, within the LISP ecosystem. We created a large-scale Internet topology simulator and used it to compare the performance of three mapping systems: LISP-DHT, LISP+ALT and the proposed LISP-TREE. We analyzed and contrasted their architectural properties as well.
The monitoring projects that supplied Internet routing table growth data over a large timespan inspired us to create LISPmon, a monitoring platform aimed at collecting, storing and presenting data gathered from the LISP pilot network, early in the deployment of the LISP protocol. The project web site and collected data is publicly available and will assist researchers in studying the evolution of the LISP mapping system.
We also document how the newly introduced LISP network elements fit into the current Internet, advantages and disadvantages of different deployment options, and how the proposed transition mechanism scenarios could affect the evolution of the global routing system. This work is currently available as an active Internet Engineering Task Force (IETF) Internet Draft.
The second part looks at the problem of efficient one-to-many communications, assuming a routing system that implements the above mentioned locator/identifier split paradigm. We propose a network layer protocol for efficient live streaming. It is incrementally deployable, with changes required only in the same border routers that should be upgraded to support locator/identifier separation. Our proof-of-concept Linux kernel implementation shows the feasibility of the protocol, and our comparison to popular peer-to-peer live streaming systems indicates important savings in inter-domain traffic.
We believe LISP has considerable potential of getting adopted, and an important aspect of this work is how it might contribute towards a better mapping system design, by showing the weaknesses of current favorites and proposing alternatives. The presented results are an important step forward in addressing the routing scalability problem described in RFC 4984, and improving the delivery of live streaming video over the Internet
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