De-ossifying the Internet Transport Layer : A Survey and Future Perspectives

ACKNOWLEDGMENT The authors would like to thank the anonymous reviewers for their useful suggestions and comments.Peer reviewedPublisher PD

NEAT : A Platform- And Protocol-Independent Internet Transport API

ACKNOWLEDGMENT The authors would like to thank the anonymous reviewers for their useful remarks. This work has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 644334 (NEAT). The views expressed are solely those of the authors.Peer reviewedPostprin

High Availability using Reliable Server Pooling

Providing fault tolerancy is crucial for a growing number of IP-based applications. There exist a lot of proprietary solutions for this problem, but free alternatives are rare. Currently, the IETF RSerPool working group is standardizing a protocol suite for Reliable Server Pooling, which copes with the challenge of providing high availability by using redundant servers. Servers for the same service are grouped into a server pool. A server in a pool is called pool element (PE), a user of a pool is called pool user (PU). When a PE fails, its PUs simply select another one from the pool and initiates an application-specific failover procedure. This fail-over is supported by the RSerPool protocol suite. Each PE registers at a name server and is then continously supervised by that specific name server. All name servers of an operational scope provide a redundant system for name resolution from pool handles to transport addresses of pool elements to pool users. RSerPool uses SCTP to provide network fault tolerance and address scoping functionality. The RSPLIB is a prototype implementation of the RSerPool protocol suite, developed under the GNU Public License in cooperation between Siemens and the Computer Networking Technology Group of the University of Essen. It currently runs under Linux, FreeBSD and Darwin

Load Distribution Performance of the Reliable Server Pooling Framework

The Reliable Server Pooling~(RSerPool) protocol suite currently under standardization by the IETF is designed to build systems providing highly available services by providing mechanisms and protocols for establishing, configuring, accessing and monitoring pools of server resources. While availability is one main aspect of RSerPool, load distribution is another. Since most of the time a server pool system runs without component failures, optimal performance is an extremely important issue for the productivity and cost-efficiency of the system. In this paper, we therefore focus especially on the load distribution performance of RSerPool in scenarios without failures, presenting a quantitative performance comparison of the different load distribution strategies (called pool policies) defined in the RSerPool specifications. Based on the results, we propose some new pool policies providing significant performance enhancements compared to those currently defined in the standards documents

Congestion and Flow Control in the Context of the Message-oriented Protocol SCTP

Abstract. Congestion and flow control are key mechanisms used to regulate the load in modern packet networks. The new IETF Stream Control Transmission Protocol (SCTP) inherited these algorithms from the Transmission Control Protocol (TCP). Although the principles used are the same, some issues arise from the fact that SCTP operates messageoriented whereas TCP operates byte-stream oriented. SCTP also supports bundling of multiple small user messages into one SCTP packet. As a consequence, the overall overhead of an SCTP packet depends on the user message size and the number of user messages that are bundled into the packet. RFC 4960 defining SCTP does not specify whether the message specific headers have to be considered when updating the parameters for congestion control. We will show that neglecting the additional headers when calculating outstanding bytes can lead to unfairness towards TCP connections. We will also show that incorrect handling of the additional memory needed to process each message in the flow control calculations will lead to an exhaustion of the receiver window resulting in a huge amount of unnecessary retransmissions. Based on experiments with the flow control of the SCTP implementations available in several operating systems, we will identify the issues and analyze them by using simulations. As a result, we will present solutions that will lead to fairness towards TCP and reduce the number of retransmissions substantially. Although we will focus on SCTP, the results are also true for other message-oriented protocols using bundling

A new Scheme for IP-based Internet-Mobility

In this contribution we present a new type of mobility management for IP-based networks that, contrary to conventional approaches, does not focus on the network layer, but on the transport and session layers. At the heart of this new mobility concept is the reliable transport protocol SCTP, with an enhancement for dynamic address reconfiguration. This is described in this paper. A session layer based on the reliable server pooling (RSerPool) protocol suite provides for sessionmonitoring and control. The suggested solution is transparent for applications,requires no changes in the network infrastructure, and is evaluated with a real-world implementation. Finally, we present first results from the application of this mobility concept to different mobility scenarios. These were obtained from working SCTP and RSerPool implementations that have been developed within our group

On the Use of Concurrent Multipath Transfer over Asymmetric Paths

With the deployment of more and more resilience-critical Internet applications, there is a rising demand for multihomed network sites. This leads to the desire for simultaneously utilising all available access paths to improve application data throughput. This is commonly known as Concurrent Multipath Transfer (CMT); approaches for several Transport Layer protocols have been proposed. Combined with Resource Pooling (RP), CMT can also fairly coexist with concurrent non-CMT flows. Current approaches focus on symmetric paths (i.e. similar bandwidth, delay and error rate). However, asymmetric paths are much more likely – particularly for realistic Internet setups – and efficient CMT usage on such paths is therefore crucial. In this paper, we first show the challenges of plain as well as RP-aware CMT data transport over asymmetric paths. After that, we introduce mechanisms for efficient transport over such paths. Finally, we analyse the performance of our approaches by using simulations