Network Transmission frontier-mptcp Technology Analysis

Cutting-edge data transmission technology-Analysis of mptcp Technology

Liu honggang

School of computer and electronic information, Guangxi University 707

Summary

Multi-host environments have become increasingly common, especially for mobile users. In transmission files, mptcp (multi-path TCP) has been proposed to effectively use multiple access points for transmission. Mptcp is a new protocol released by IETF in January 2013. Mptcp can distribute data through multiple paths in a single connection. However, the deployment and adoption of a protocol is not a trivial matter. The deployment protocol must take into account all stakeholders as a sufficient and necessary condition for protocol deployment. In addition, the original multi-path TCP does not make full use of the bandwidth, and does not fully consider the energy efficiency and cost issues. This article mainly analyzes the opportunities and challenges in mptcp protocol deployment, as well as the existing problems and some improvement solutions in multi-path TCP.

Keywords: Mptcp deployment of multi-host atlb

I. Introduction

Multi-host environments have become increasingly common, especially for mobile users. Now, you can configure Ethernet, Wi-Fi, and Bluetooth interfaces for your laptop. Mobile users also have 2g, 3G, 4G, Wi-Fi, Bluetooth, and infrared interfaces. The emergence of these available network interfaces and users' demand for improved data transmission rates have forced the emergence of a new data transmission technology-mptcp (multi-path TCP ). Mptcp, as an extension of TCP, was precisely defined by IETF (Internet Engineering Project Team) in 2013. The mptcp technology allows data to be transmitted through multiple substreams during a connection, which improves the available bandwidth for data transmission. Mptcp can be well applied in wireless networks-using WiFi interfaces and mobile networks is a typical application. In addition, it increases the data throughput and solves the problem of vertical switching at the application layer. Mptcp also brings good benefits in data centers. However, the mptcp protocol deployment still faces some challenges. Currently, all standard protocols on the Internet use a path for data transmission between the source and destination. Therefore, to deploy a new protocol (such as mptcp), several factors must be taken into account: 1. compared with previous protocols, this protocol can better meet a specific requirement and solve a specific problem. For example, when downloading large files (videos or applications), it is better than other transport layer solutions. 2. This Protocol must be compatible with traditional protocols. It can be the same as traditional TCP and UDP, and can be connected to other middleware through firewalls. There are still many problems in mptcp. These problems are mainly manifested in the following aspects: 1. mpctp consumes more energy than traditional TCP, which is important to mobile users; 2. internet service providers have not yet provided mptcp services to end users; 3. mptcp does not consider network latency and congestion control; 4. mptcp does not guarantee load balancing. These problems all impede the rapid popularization of mptcp.

In this paper, we mainly analyze the problems in the deployment of mptcp and the problems in the specific mptcp technology, and the related improvement solutions and performance analysis that have been proposed. The following parts of the thesis are organized as follows: the second part briefly introduces the design model and transmission process of mptcp, and the key components of mptcp. The third part briefly introduces the factors to be considered in mptcp deployment; the fourth part describes the improved load balancing model in mptcp; the fifth part is the summary and prospects of the paper.

 

Ii. Composition and communication process of mptcp

This section describes the components of mptcp and the communication process.

The framework 1 of mptcp and the Framework Structure of mptcp.

 

Figure 1 Framework Structure of mptcp

From the Framework Structure of mptcp, we can see that mptcp is located under the application layer and over the IP layer, which replaces the original TCP layer and is divided into two sub-layers: mptcp layer and TCP layer. In mptcp, there are four key words:

• 1. Path: A connection sequence between the sender and receiver
• 2. substream: A single TCP connection. These connections constitute an mp tcp connection. The substream starts and ends with a conventional TCP connection.
• 3. mptcp: a set of one or more sub-streams through which two hosts can communicate.
• 4. Token: A unique local identifier in a path in a host. Actually, it is a connection ID.

The transmission process of mptcp is assumed 2, which contains an application layer and a transmission layer. The transport layer is divided into two child layers: mptcp and TCP. When you use mptcp for communication, it opens n TCP connections at the same time, and N is the number of paths between the sending end and the receiving end. The Application Layer sends data to the mptcp layer. Then, the mptcp layer divides the data into multiple segments and adds a control segment header to each segment. The control header contains a serial number, which is used to reorganize data at the receiving end. The mptcp layer then transmits the data to the TCP layer. When the receiving end receives the data sent from the peer end, the receiving end reads the data and reassembles the data according to the control header, and then transmits the data to the application layer.

The figure shows that the sender uses mptcp to send data, divides the data into five segments on the sender end, and then transmits the data to the receiver through 1, 2. The number in the box in the figure represents the serial number of the segment.

 

Figure 2 mptcp transmission process

Iii. Deployment of mptcp

This section describes the process of successfully deploying the mptcp framework. It is very important to differentiate deployment and adoption. Deployment refers to the network environment deployed in mptcp. Adoption refers to the addition of some additional steps when deployment is possible, which means that end users actually use this protocol when sending data.

Protocol deployment consists of three parts: 3. mptcp protocol deployment process:

 

Figure 3 mptcp deployment process

The first step of Protocol adoption is that it is highly efficient and deployable. The minimum requirement is that mptcp has some advantages over the previous protocol, it cannot be a sufficient and necessary condition for adoption. Internet is a responsible system, and deployment protocols usually need to consider some stakeholders. This is why it is feasible for every stakeholder. If a protocol is deployable, the actual deployment process must be considered. This step shows that the deployment behavior requires different stakeholders to allow such protocol deployment. Before mptcp is used, three requirements must be met. First, the operating system provider must implement mptcp and install it to end users. The second is that one user must have multi-host performance. For example, the operating system allows end users to connect to the Internet in multiple ways, and end users can connect to the Internet through different Internet interfaces. Third, other terminal systems must be gradually compatible with mptcp, so that mptcp can be used by end users.

After the protocol is deployed, it does not really mean it is adopted. Therefore, a deeper investigation is needed, which is mainly related to key stakeholders and potential business models that can facilitate adoption of mptcp.

 

 

Iv. mptcp Load Balancing Improvement Plan

Although traditional mptcp can transmit data through multiple paths, congestion control is not taken into account during data transmission, because traditional data distribution is unconscious, therefore, this may cause congestion of a path. Because the receiving end needs a data block to arrive completely before it can be sorted and then submitted to the application layer, congestion will cause data to not arrive in order, which will affect the transmission speed, and because of waiting, the subsequent data continues to arrive, which leads to an increasing number of receiving windows at the receiving end, resulting in window overflow. To solve this problem, this paper proposes an improved solution.

The core idea of this solution is to assess the degree of path congestion at the sending end, and choose the path with the lowest congestion each time. Because the path with the lowest congestion is selected every time, the data can be delivered in order, which solves the bottleneck of receiving end sorting.

In order to assess the Congestion Degree of the path, we propose 4 solutions. At the transport layer, set an atlb (Server Load balancer with Time-of-arrival matching) operation. This operation selects the data distribution path by evaluating the path score each time. This method is used to evaluate the path score every time: score = the length of the transmission queue of path I/the throughput of the smooth path I + the round-trip delay/2 after the smooth. The formula shows that the lower the score, the lower the congestion level. Therefore, select a path with low congestion level to transmit data.

 

Figure 4 atlb Data Distribution

The mathematical expression of the formula is as follows:

 

It indicates the score of path I, which is the length of queue I, GI is the smooth throughput of queue I, and it is the smooth RTT.

 

Gj is the J-th throughput value, which is jointly determined by the Gj-1 and tputj. α (0 <α <1) is a constant, and tputj is the throughput calculated per beta millisecond.

V. Summary

This paper mainly analyzes the transmission process of mptcp and the challenges and opportunities of mptcp deployment. In deployment, there are three steps: Deployment protocol design, deployment process, and adoption. Protocol deployment is a complex process and many factors must be taken into account. For example, the Protocol itself has more advantages than the previous protocol, and the protocol must take relevant stakeholders into account, consider operating system providers and related business providers. Then we analyze atlb, a method of mptcp to improve load balancing. This method is to always find the least blocking path to distribute data before each data distribution, which ensures data load balancing and solves the data sorting problem at the receiving end.

 

Vi. References

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[9] C. raiciu, M. Handley, and D. wischik. Coupled multipath-aware congestion control draft-raicu-mptcp-congestion-01. Internet Engineering Task Force Internet Draft, 2010.

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Network Transmission frontier-mptcp Technology Analysis