Understanding multi-protocol label switching technology in VPN - 2

Figure 3.1

INTRODUCTION

Along with the trend of globalization, the expansion of international cooperation and exchanges is increasing, business cooperation is not only limited to a district, a province, a country but also expands to the whole world. A company can have branches, business partners in many countries and there is always a need to exchange information with each other. To ensure the confidentiality of the information exchanged, according to the traditional way of communication, people use private channels, but the disadvantage is that it is expensive, causing waste of resources when the data exchanged is not much and not regular. Therefore, people have researched other technologies that can still meet the need for information exchange but are less expensive and more convenient, that is the virtual private network solution.

VPN is defined as a network connecting customer sites that ensures security on a common network infrastructure with access control policies and security assurance like a private network. There have been many VPN implementation options such as: X.25, ATM, Framer Relay, ... However, when implementing these solutions, the cost of purchasing equipment, operating, maintaining, and managing is very high and must be borne by the business while service providers only ensure a private channel for data and are not sure about the security of this private channel.

Organizations and businesses using IP VPN services will save a lot of costs in connecting branch offices together, remotely accessing the internal network, and making VoIP calls. Currently, ADSL has become popular and low cost, so implementing IP VPN becomes very simple and effective because it takes advantage of high-speed Internet connection.

The purpose of this project is to understand the fundamental issues involved in implementing IP-VPN and MPLS – VPN. Evaluate these two technologies.

The project layout includes 3 chapters:

Chapter 1: TCP/IP protocol suite and virtual private network technology on the Internet IP-

VPN

Chapter 2: IPSec Protocol for IP-VPN

Chapter 3: Multiprotocol Label Switching in VPN

Despite receiving a lot of help from her instructor and her efforts,

but the project is not without mistakes so I hope to receive more contributions and opinions from teachers, friends and people interested in this field.

CHAPTER 1: TCP/IP PROTOCOL SUITE AND

VIRTUAL PRIVATE NETWORK TECHNOLOGY ON INTERNET IP-VPN

1.1 Internet concept

In June 1968, an agency of the US Department of Defense, the Advanced Research Projects Agency (ARPA), built a project to connect major research centers across the federal government with the goal of sharing and exchanging information resources, marking the birth of ARPANET - the predecessor of today's Internet. Initially, the communication protocol used in the ARPANET network was NCP (Network Control Protocol), but was later replaced by the TCP/IP protocol suite (Transfer Control Protocol/Internet Protocol) . Protocol suiteTCP/IP is a set of networking standards that specify how computerscommunication with each other, as well as conventions for interconnection and routing for

network.

Previously, people defined “Internet as the network of all networks using

IP protocol”. But today, that is no longer accurate because many networks have

different architectures but thanks to protocol bridges can still connect to each other

Internet and still be able to use full range of Internet services. The Internet is not just a

A collection of interconnected networks, Internetworking also means networks that are interconnected on the basis of mutually agreed conventions that allow computers to communicate with each other, even if the communication path will pass through networks to which they are not directly connected. Thus, Internet technology hides the details

network hardware, and allows computer systems to exchange information independently of each other.

their physical network links.

TCP/IP has the following features that have made it popular:

- Independent of network architecture: TCP/IP can be used in Ethernet, Token Ring architectures, in local area networks (LAN) as well as wide area networks (WAN).

- Open protocol standard: because TCP/IP can be implemented on any hardware or operating system. Therefore, TCP/IP is an ideal protocol set to combine different hardware and software.

- Global addressing scheme: each computer on the TCP/IP network has a unique address. Each data packet sent on the TCP/IP network has a Header that includes the address of the destination computer as well as the address of the source computer.

- Client - Server Framework: TCP/IP is the framework for powerful client - server applications that operate on local and wide area networks.

1.2 TCP/IP protocol suite layered model

The TCP/IP protocol suite is a combination of different protocols at different layers, not just TCP and IP protocols. Each layer has its own function. The TCP/IP model is organized into 4 layers (from the application side down to the physical layer) as follows:

Figure 1.1: TCP/IP protocol suite layered model

 Application layer: Controls the details of each specific application. It corresponds to the application layers, presented in the OSI model. It includes high-level protocols, encryption, conversation control ... Application services such as SMTP, FTP, TFTP ... Currently, there are hundreds or even thousands of protocols in this layer. Application programs communicate with protocols in the transport layer to transmit and receive data. Application programs transmit data in the form of requests to the transport layer for processing before transferring it to the Internet layer to find a route.

 Transport layer: Responsible for message transmission(message) from one process (a running program) to another. The transport layer ensures that the information arrives at the destination error-free and in order. It has two very different protocols: the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP).

 Internet layer: Provides hardware-independent addressing functionality that allows data to move between subnets with different physical architectures. This layer controls packet forwarding across the network, packet routing. (Supports inter-IP protocol - the concept of internetwork refers to a larger network: a network that connects networks

LAN). The protocols of this layer are IP, ICMP, ARP, RARP.

 Network Access Network: Provides interface to the physical network. (Usually this layer includes device drivers in the operating system and corresponding network interface cards in the computer. This layer performs the task of controlling all hardware details or performing physical interface with the cable (or with any medium used)). Provides error control of data distributed over the physical network. This layer does not define any specific protocol, it supports all standard and proprietary protocols. For example: Ethernet, Token Ring, FDDI, X.25, wireless, Async, ATM, SNA…

1.3 Protocols in the TCP/IP model

1.3.1 Internet Protocol

1.3.1.1 General introduction

The purpose of the Internet protocol is to transfer information (data) from source to destination. IP uses datagrams. Each datagram contains a destination address and IP uses this information to route the packet to its destination via the appropriate path. Packets from the same pair of users use different information paths, routing is separate for each packet. The IP protocol does not maintain state, after a datagram is delivered the sender no longer stores any information about it, so there is no way to detect lost packets and can lead to duplicated and out-of-order packets.

1.3.1.2. IPv4 structure

Information received from the transport layer is added to the IP header. This header is 20 to 60 bytes long and travels along the path depending on the optional functions used. The structure of an IPv4 packet is shown in Figure 1.2.

00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

version

hdr length	Type of service	Total length (bytes)
Identification			Flags	Fragment offset
Time - to - live		Protocol	Header checksum
Source IP address
Destination IP address
Options and padding
Data

Maybe you are interested!

• Multi Point Control Protocol (Mpcp)
• Mobile Phone Usage in Hanoi Inner City Area zt2i3t4l5ee zt2a3gsconsumer,consumption,consumer behavior,marketing,mobile marketing zt2a3ge zc2o3n4t5e6n7ts - Test the relationship between demographic variables and consumer behavior for Mobile Marketing activities The analysis method used is the Chi-square test (χ2), with statistical hypotheses H0 and H1 and significance level α = 0.05. In case the P index (p-value) or Sig. index in SPSS has a value less than or equal to the significance level α, the hypothesis H0 is rejected and vice versa. With this testing procedure, the study can evaluate the difference in behavioral trends between demographic groups. CHAPTER 4 RESEARCH RESULTS During two months, 1,100 survey questionnaires were distributed to mobile phone users in the inner city of Hanoi using various methods such as direct interviews, sending via email or using questionnaires designed on the Internet. At the end of the survey, after checking and eliminating erroneous questionnaires, the study collected 858 complete questionnaires, equivalent to a rate of about 78%. In addition, the research subjects of the thesis are only people who are using mobile phones, so people who do not use mobile phones are not within the scope of the thesis, therefore, the questionnaires with the option of not using mobile phones were excluded from the scope of analysis. The number of suitable survey questionnaires included in the statistical analysis was 835. 4.1 Demographic characteristics of the sample The structure of the survey sample is divided and statistically analyzed according to criteria such as gender, age, occupation, education level and personal income. (Detailed statistical table in Appendix 6) - Gender structure: Of the 835 completed questionnaires, 49.8% of respondents were male, equivalent to 416 people, and 50.2% were female, equivalent to 419 people. The survey results of the study are completely consistent with the gender ratio in the population structure of Vietnam in general and Hanoi in particular (Male/Female: 49/51). - Age structure: 36.6% of respondents are <23 years old, equivalent to 306 people. People from 23-34 years old accounting for the highest proportion: 44.8% equivalent to 374 people, people aged 35-45 and >45 are 70 and 85 people equivalent to 8.4% and 10.2% respectively. Looking at the results of this survey, we can see that the young people - youth account for a large proportion of the total number of people participating in the survey. Meanwhile, the middle-aged people including two age groups of 35 - 45 and >45 have a low rate of participation in the survey. This is completely consistent with the reality when Mobile Marketing is identified as a Marketing service aimed at young people (people under 35 years old). - Structure by educational level: among 835 valid responses, 541 respondents had university degrees, accounting for the highest proportion of ~ 75%, 102 had secondary school degrees, ~ 13.1%, and 93 had post-graduate degrees, ~ 11.9%. - Occupational structure: office workers and civil servants are the group with the highest rate of participation with 39.4%, followed by students with 36.6%. Self-employed people account for 12%, retired housewives are 7.8% and other occupational groups account for 4.2%. The survey results show that the student group has the same rate as the group aged <23 at 36.6%. This shows the accuracy of the survey data. In addition, the survey results distributed by occupational criteria have a rate almost similar to the sample division rate in chapter 3. Therefore, it can be concluded that the survey data is suitable for use in analysis activities. - Income structure: the group with income from 3 to 5 million has the highest rate with 39% of the total number of respondents. This is consistent with the income structure of Hanoi people and corresponds to the average income of the group of civil servants and office workers. Those People with no income account for 23%, income under 3 million VND accounts for 13% and income over 5 million VND accounts for 25%. 4.2 Mobile phone usage in Hanoi inner city area According to the survey results, most respondents said they had used the phone for more than 1 year, specifically: 68.4% used mobile phones from 4 to 10 years, 23.2% used from 1 to 3 years, 7.8% used for more than 10 years. Those who used mobile phones for less than 1 year accounted for only a very small proportion of ~ 0.6%. (Table 4.1) Table 4.1: Time spent using mobile phones Frequency Ratio (%) Valid Percentage Cumulative Percentage Alid <1 year 5 .6 .6 .6 1-3 years 194 23.2 23.2 23.8 4-10 years 571 68.4 68.4 92.2 >10 years 65 7.8 7.8 100.0 Total 835 100.0 100.0 The survey indexes on the time of using mobile phones of consumers in the inner city of Hanoi are very impressive for a developing country like Vietnam and also prove that Vietnamese consumers have a lot of experience using this high-tech device. Moreover, with the majority of consumers surveyed having a relatively long time of use (4-10 years), it partly proves that mobile phones have become an important and essential item in people's daily lives. When asked about the mobile phone network they are using, 31% of respondents said they are using the network of Vietel company, 29% use the network of of Mobifone company, 27% use Vinaphone company's network and 13% use networks of other providers such as E-VN telecom, S-fone, Beeline, Vietnammobile. (Figure 4.1). Figure 4.1: Mobile phone network in use Compared with the announced market share of mobile telecommunications service providers in Vietnam (Vietel: 36%, Mobifone: 29%, Vinaphone: 28%, the remaining networks: 7%), we see that the survey results do not have many differences. However, the statistics show that there is a difference in the market share of other networks because the Hanoi market is one of the two main markets of small networks, so their market share in this area will certainly be higher than that of the whole country. According to a report by NielsenMobile (2009) [8], the number of prepaid mobile phone subscribers in Hanoi accounts for 95% of the total number of subscribers, however, the results of this survey show that the percentage of prepaid subscribers has decreased by more than 20%, only at 70.8%. On the contrary, the number of postpaid subscribers tends to increase from 5% in 2009 to 19.2%. Those who are simultaneously using both types of subscriptions account for 10%. (Table 4.2). Table 4.2: Types of mobile phone subscribers Frequency Ratio (%) Valid Percentage Cumulative Percentage Valid Prepay 591 70.8 70.8 70.8 Pay later 160 19.2 19.2 89.9 Both of the above 84 10.1 10.1 100.0 Total 835 100.0 100.0 The above figures show the change in the psychology and consumption habits of Vietnamese consumers towards mobile telecommunications services, when the use of prepaid subscriptions and junk SIMs is replaced by the use of two types of subscriptions for different purposes and needs or switching to postpaid subscriptions to enjoy better customer care services. In addition, the majority of respondents have an average spending level for mobile phone services from 100 to 300 thousand VND (406 ~ 48.6% of total respondents). The high spending level (> 500 thousand VND) is the spending level with the lowest number of people with only 8.4%, on the contrary, the low spending level (under 100 thousand VND) accounts for the second highest proportion among the groups of respondents with 25.4%. People with low spending levels mainly fall into the group of students and retirees/housewives - those who have little need to use or mainly use promotional SIM cards. (Table 4.3). Table 4.3: Spending on mobile phone charges Frequency Ratio (%) Valid Percentage Cumulative Percentage Valid <100,000 212 25.4 25.4 25.4 100-300,000 406 48.6 48.6 74.0 300,000-500,000 147 17.6 17.6 91.6 >500,000 70 8.4 8.4 100.0 Total 835 100.0 100.0 The statistics in Table 4.3 are similar to the percentages in the NielsenMobile survey results (2009) with 73% of mobile phone users having medium spending levels and only 13% having high spending levels. The survey results also showed that up to 31% ~ nearly one-third of respondents said they sent more than 10 SMS messages/day, meaning that on average they sent 1 SMS message for every working hour. Those with an average SMS message volume (from 3 to 10 messages/day) accounted for 51.1% and those with a low SMS message volume (less than 3 messages/day) accounted for 17%. (Table 4.4) Table 4.4: Number of SMS messages sent per day Frequency Ratio (%) Valid Percentage Cumulative Percentage Valid <3 news 142 17.0 17.0 17.0 3-10 news 427 51.1 51.1 68.1 >10 news 266 31.9 31.9 100.0 Total 835 100.0 100.0 Similar to sending messages, those with an average message receiving rate (from 3-10 messages/day) accounted for the highest percentage of ~ 55%, followed by those with a high number of messages (over 10 messages/day) ~ 24% and those with a low number of messages received daily (under 3 messages/day) remained at the bottom with 21%. (Table 4.5) Table 4.5: Number of SMS messages received per day Frequency Ratio (%) Valid Percentage Cumulative Percentage Valid <3 news 175 21.0 21.0 21.0 3-10 news 436 55.0 55.0 76.0 >10 news 197 24.0 24.0 100.0 Total 835 100.0 100.0 When comparing the data of the two result tables 4.4 and 4.5, we can see the reasonableness between the ratio of the number of messages sent and the number of messages received daily by the interview participants. 4.3 Current status of SMS advertising and Mobile Marketing According to the interview results, in the 3 months from the time of the survey and before, 94% of respondents, equivalent to 785 people, said they received advertising messages, while only a very small percentage of 6% (only 50 people) did not receive advertising messages (Table 4.6). Table 4.6: Percentage of people receiving advertising messages in the last 3 months Frequency Ratio (%) Valid Percentage Cumulative Percentage Valid Have 785 94.0 94.0 94.0 Are not 50 6.0 6.0 100.0 Total 835 100.0 100.0 The results of Table 4.6 show that consumers in the inner city of Hanoi are very familiar with advertising messages. This result is also the basis for assessing the knowledge, experience and understanding of the respondents in the interview. This is also one of the important factors determining the accuracy of the survey results. In addition, most respondents said they had received promotional messages, but only 24% of them had ever taken the action of registering to receive promotional messages, while 76% of the remaining respondents did not register to receive promotional messages but still received promotional messages every day. This is the first sign indicating the weaknesses and shortcomings of lax management of this activity in Vietnam. (Table 4.7) div.maincontent .s1 { color: black; font-family:"Times New Roman", serif; font-style: italic; font-weight: normal; text-decoration: none; font-size: 14pt; } div.maincontent .s2 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 14pt; } div.maincontent .s3 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 14pt; } div.maincontent .p { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 14pt; margin:0pt; } div.maincontent p { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 14pt; margin:0pt; } div.maincontent .s4 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 9.5pt; vertical-align: 6pt; } div.maincontent .s5 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 14pt; } div.maincontent .s6 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 14pt; } div.maincontent .s7 { color: black; font-family:"Times New Roman", serif; font-style: italic; font-weight: normal; text-decoration: none; font-size: 14pt; } div.maincontent .s8 { color: black; font-family:"Times New Roman", serif; font-style: italic; font-weight: bold; text-decoration: none; font-size: 14pt; } div.maincontent .s9 { color: black; font-family:Arial, sans-serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 14pt; } div.maincontent .s10 { color: black; font-family:Arial, sans-serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 12pt; } div.maincontent .s11 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; font-size: 14pt; } div.maincontent .s12 { color: black; font-family:Arial, sans-serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 14pt; } div.maincontent .s13 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 14pt; } div.maincontent .s14 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 13pt; } div.maincontent .s15 { color: black; font-family:"Times New Roman", serif; font-style: italic; font-weight: normal; text-decoration: none; font-size: 9.5pt; vertical-align: 6pt; } div.maincontent .s16 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 5.5pt; vertical-align: 3pt; } div.maincontent .s17 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 8.5pt; } div.maincontent .s18 { color: black; font-family:"Times New Roman", serif; font-style: italic; font-weight: bold; font-size: 14pt; } div.maincontent .s19 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: bold; font-size: 14pt; } div.maincontent .s20 { color: black; font-family:"Times New Roman", serif; font-style: italic; font-weight: normal; text-decoration: none; font-size: 13pt; } div.maincontent .s21 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 14pt; } div.maincontent .s22 { color: black; font-family:"Courier New", monospace; font-style: normal; font-weight: normal; text-decoration: none; font-size: 14pt; } div.maincontent .s23 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 13pt; } div.maincontent .s24 { color: black; font-family:"Times New Roman", serif; font-style: italic; font-weight: normal; text-decoration: none; font-size: 13pt; } div.maincontent .s25 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 14pt; } div.maincontent .s26 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 14pt; } div.maincontent .s27 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 1.5pt; } div.maincontent .s28 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 11pt; } div.maincontent .s29 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 13pt; } div.maincontent .s30 { color: black; font-family:"Times New Roman", serif; font-style: italic; font-weight: bold; text-decoration: none; font-size: 13pt; } div.maincontent .s31 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 13pt; } div.maincontent .s32 { color: black; font-family:Arial, sans-serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 10.5pt; } div.maincontent .s33 { color: black; font-family:Arial, sans-serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 11pt; } div.maincontent .s35 { color: black; font-family:Arial, sans-serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 10.5pt; } div.maincontent .s36 { color: #F00; font-family:Arial, sans-serif; font-style: italic; font-weight: bold; text-decoration: none; font-size: 10.5pt; } div.maincontent .s37 { color: black; font-family:Arial, sans-serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 10.5pt; } div.maincontent .s38 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 8.5pt; vertical-align: 5pt; } div.maincontent .s39 { color: black; font-family:Arial, sans-serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 10.5pt; } div.maincontent .s40 { color: black; font-family:Arial, sans-serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 7pt; vertical-align: 4pt; } div.maincontent .s41 { color: black; font-family:Arial, sans-serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 10.5pt; } div.maincontent .s42 { color: black; font-family:Arial, sans-serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 11pt; } div.maincontent .s43 { color: black; font-family:Arial, sans-serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 7.5pt; vertical-align: 5pt; } div.maincontent .s44 { color: black; font-family:Arial, sans-serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 7pt; vertical-align: 5pt; } div.maincontent .s45 { color: #F00; font-family:Arial, sans-serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 10.5pt; } div.maincontent .s46 { color: black; font-family:Arial, sans-serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 7pt; vertical-align: 5pt; } div.maincontent .s47 { color: black; font-family:Arial, sans-serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 11pt; } div.maincontent .s48 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 14pt; } div.maincontent .s49 { color: black; font-family:"Times New Roman", serif; font-style: italic; font-weight: normal; text-decoration: none; font-size: 9.5pt; vertical-align: -2pt; } div.maincontent .s50 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 9.5pt; } div.maincontent .s51 { color: black; font-family:"Times New Roman", serif; font-style: italic; font-weight: normal; text-decoration: none; font-size: 9.5pt; vertical-align: -1pt; } div.maincontent .s52 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 9.5pt; vertical-align: -2pt; } div.maincontent .s53 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 13pt; } div.maincontent .s54 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 9.5pt; vertical-align: -1pt; } div.maincontent .s55 { color: black; font-family:Arial, sans-serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 10.5pt; } div.maincontent .s56 { color: #00F; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; font-size: 14pt; } div.maincontent .s57 { color: #00F; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 14pt; } div.maincontent .s58 { color: #00F; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; font-size: 14pt; } div.maincontent .s59 { color: #00F; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 13pt; } div.maincontent .s60 { color: #00F; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; font-size: 13pt; } div.maincontent .s61 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 14pt; } div.maincontent .s62 { color: black; font-family:"Times New Roman", serif; font-style: italic; font-weight: bold; text-decoration: none; font-size: 14pt; } div.maincontent .s63 { color: black; font-family:"Times New Roman", serif; font-style: italic; font-weight: bold; text-decoration: none; font-size: 14pt; } div.maincontent .content_head2 { color: #F00; font-family:"Times New Roman", serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 14pt; } div.maincontent .s64 { color: black; font-family:"Times New Roman", serif; font-style: italic; font-weight: bold; text-decoration: none; font-size: 13pt; } div.maincontent .s67 { color: black; font-family:Arial, sans-serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 9.5pt; } div.maincontent .s68 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 12pt; } div.maincontent .s69 { color: black; font-family:"Times New Roman", serif; font-style: italic; font-weight: normal; text-decoration: none; font-size: 12pt; } div.maincontent .s70 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; tex
• Qos Assurance Methods for Multimedia Communications zt2i3t4l5ee zt2a3gs zt2a3ge zc2o3n4t5e6n7ts low. The EF PHB requires a sufficiently large number of output ports to provide low delay, low loss, and low jitter. EF PHBs can be implemented if the output port's bandwidth is sufficiently large, combined with small buffer sizes and other network resources dedicated to EF packets, to allow the router's service rate for EF packets on an output port to exceed the arrival rate λ of packets at that port. This means that packets with PHB EF are considered with a pre-allocated amount of output bandwidth and a priority that ensures minimum loss, minimum delay and minimum jitter before being put into operation. PHB EF is suitable for channel simulation, leased line simulation, and real-time services such as voice, video without compromising on high loss, delay and jitter values. Figure 2.10 Example of EF installation Figure 2.10 shows an example of an EF PHB implementation. This is a simple priority queue scheduling technique. At the edges of the DS domain, EF packet traffic is prioritized according to the values ​​agreed upon by the SLA. The EF queue in the figure needs to output packets at a rate higher than the packet arrival rate λ. To provide an EF PHB over an end-to-end DS domain, bandwidth at the output ports of the core routers needs to be allocated in advance to ensure the requirement μ > λ. This can be done by a pre-configured provisioning process. In the figure, EF packets are placed in the priority queue (the upper queue). With such a length, the queue can operate with μ > λ. Since EF was primarily used for real-time services such as voice and video, and since real-time services use UDP instead of TCP, RED is generally not suitable for EF queues because applications using UDP will not respond to random packet drop and RED will strip unnecessary packets. 2.2.4.2 Assured Forwarding (AF) PHB PHB AF is defined by RFC 2597. The purpose of PHB AF is to deliver packets reliably and therefore delay and jitter are considered less important than packet loss. PHB AF is suitable for non-real-time services such as applications using TCP. PHB AF first defines four classes: AF1, AF2, AF3, AF4. For each of these AF classes, packets are then classified into three subclasses with three distinct priority levels. Table 2.8 shows the four AF classes and 12 AF subclasses and the DSCP values ​​for the 12 AF subclasses defined by RFC 2597. RFC 2597 also allows for more than three separate priority levels to be added for internal use. However, these separate priority levels will only have internal significance. PHB Class PHB Subclass Package type DSCP AF4 AF41 Short 100010 AF42 Medium 100100 AF43 High 100110 AF3 AF31 Short 011010 AF32 Medium 011100 AF33 High 011110 AF2 AF21 Short 010010 AF22 Medium 010100 AF23 High 010110 AF1 AF11 Short 001010 AF12 Medium 001100 AF13 High 001110 Table 2.8 AF DSCPs The AF PHB ensures that packets are forwarded with a high probability of delivery to the destination within the bounds of the rate agreed upon in an SLA. If AF traffic at an ingress port exceeds the pre-priority rate, which is considered non-compliant or “out of profile”, the excess packets will not be delivered to the destination with the same probability as the packets belonging to the defined traffic or “in profile” packets. When there is network congestion, the out of profile packets are dropped before the in profile packets are dropped. When service levels are defined using AF classes, different quantity and quality between AF classes can be realized by allocating different amounts of bandwidth and buffer space to the four AF classes. Unlike EF, most AF traffic is non-real-time traffic using TCP, and the RED queue management strategy is an AQM (Adaptive Queue Management) strategy suitable for use in AF PHBs. The four AF PHB layers can be implemented as four separate queues. The output port bandwidth is divided into four AF queues. For each AF queue, packets are marked with three “colors” corresponding to three separate priority levels. In addition to the 32 DSCP 1 groups defined in Table 2.8, 21 DSCPs have been standardized as follows: one for PHB EF, 12 for PHB AF, and 8 for CSCP. There are 11 DSCP 1 groups still available for other standards. 2.2.5.Example of Differentiated Services We will look at an example of the Differentiated Service model and mechanism of operation. The architecture of Differentiated Service consists of two basic sets of functions: Edge functions: include packet classification and traffic conditioning. At the inbound edge of the network, incoming packets are marked. In particular, the DS field in the packet header is set to a certain value. For example, in Figure 2.12, packets sent from H1 to H3 are marked at R1, while packets from H2 to H4 are marked at R2. The labels on the received packets identify the service class to which they belong. Different traffic classes receive different services in the core network. The RFC definition uses the term behavior aggregate rather than the term traffic class. After being marked, a packet can be forwarded immediately into the network, delayed for a period of time before being forwarded, or dropped. We will see that there are many factors that affect how a packet is marked, and whether it is forwarded immediately, delayed, or dropped. Figure 2.12 DiffServ Example Core functionality: When a DS-marked packet arrives at a Diffservcapable router, the packet is forwarded to the next router based on Per-hop behavior is associated with packet classes. Per-hop behavior affects router buffers and the bandwidth shared between competing classes. An important principle of the Differentiated Service architecture is that a router's per-hop behavior is based only on the packet's marking or the class to which it belongs. Therefore, if packets sent from H1 to H3 as shown in the figure receive the same marking as packets from H2 to H4, then the network routers treat the packets exactly the same, regardless of whether the packet originated from H1 or H2. For example, R3 does not distinguish between packets from h1 and H2 when forwarding packets to R4. Therefore, the Differentiated Service architecture avoids the need to maintain router state about separate source-destination pairs, which is important for network scalability. Chapter Conclusion Chapter 2 has presented and clarified two main models of deploying and installing quality of service in IP networks. While the traditional best-effort model has many disadvantages, later models such as IntServ and DiffServ have partly solved the problems that best-effort could not solve. IntServ follows the direction of ensuring quality of service for each separate flow, it is built similar to the circuit switching model with the use of the RSVP resource reservation protocol. IntSer is suitable for services that require fixed bandwidth that is not shared such as VoIP services, multicast TV services. However, IntSer has disadvantages such as using a lot of network resources, low scalability and lack of flexibility. DiffServ was born with the idea of ​​solving the disadvantages of the IntServ model. DiffServ follows the direction of ensuring quality based on the principle of hop-by-hop behavior based on the priority of marked packets. The policy for different types of traffic is decided by the administrator and can be changed according to reality, so it is very flexible. DiffServ makes better use of network resources, avoiding idle bandwidth and processing capacity on routers. In addition, the DifServ model can be deployed on many independent domains, so the ability to expand the network becomes easy. Chapter 3: METHODS TO ENSURE QoS FOR MULTIMEDIA COMMUNICATIONS In packet-switched networks, different packet flows often have to share the transmission medium all the way to the destination station. To ensure the fair and efficient allocation of bandwidth to flows, appropriate serving mechanisms are required at network nodes, especially at gateways or routers, where many different data flows often pass through. The scheduler is responsible for serving packets of the selected flow and deciding which packet will be served next. Here, a flow is understood as a set of packets belonging to the same priority class, or originating from the same source, or having the same source and destination addresses, etc. In normal state when there is no congestion, packets will be sent as soon as they are delivered. In case of congestion, if QoS assurance methods are not applied, prolonged congestion can cause packet drops, affecting service quality. In some cases, congestion is prolonged and widespread in the network, which can easily lead to the network being "frozen", or many packets being dropped, seriously affecting service quality. Therefore, in this chapter, in sections 3.2 and 3.3, we introduce some typical network traffic load monitoring techniques to predict and prevent congestion before it occurs through the measure of dropping (removing) packets early when there are signs of impending congestion. 3.1. DropTail method DropTail is a simple, traditional queue management method based on FIFO mechanism. All incoming packets are placed in the queue, when the queue is full, the later packets are dropped. Due to its simplicity and ease of implementation, DropTail has been used for many years on Internet router systems. However, this algorithm has the following disadvantages: − Cannot avoid the phenomenon of “Lock out”: Occurs when 1 or several traffic streams monopolize the queue, making packets of other connections unable to pass through the router. This phenomenon greatly affects reliable transmission protocols such as TCP. According to the anti-congestion algorithm, when locked out, the TCP connection stream will reduce the window size and reduce the packet transmission speed exponentially. − Can cause Global Synchronization: This is the result of a severe “Lock out” phenomenon. Some neighboring routers have their queues monopolized by a number of connections, causing a series of other TCP connections to be unable to pass through and simultaneously reducing the transmission speed. After those monopolized connections are temporarily suspended, Once the queue is cleared, it takes a considerable amount of time for TCP connections to return to their original speed. − Full Queue phenomenon: Data transmitted on the Internet often has an explosion, packets arriving at the router are often in clusters rather than in turn. Therefore, the operating mechanism of DropTail makes the queue easily full for a long period of time, leading to the average delay time of large packets. To avoid this phenomenon, with DropTail, the only way is to increase the router's buffer, this method is very expensive and ineffective. − No QoS guarantee: With the DropTail mechanism, there is no way to prioritize important packets to be transmitted through the router earlier when all are in the queue. Meanwhile, with multimedia communication, ensuring connection and stable speed is extremely important and the DropTail algorithm cannot satisfy. The problem of choosing the buffer size of the routers in the network is to “absorb” short bursts of traffic without causing too much queuing delay. This is necessary in bursty data transmission. The queue size determines the size of the packet bursts (traffic spikes) that we want to be able to transmit without being dropped at the routers. In IP-based application networks, packet dropping is an important mechanism for indirectly reporting congestion to end stations. A solution that prevents router queues from filling up while reducing the packet drop rate is called dynamic queue management. 3.2. Random elimination method – RED 3.2.1 Overview RED (Random Early Detection of congestion; Random Early Drop) is one of the first AQM algorithms proposed in 1993 by Sally Floyd and Van Jacobson, two scientists at the Lawrence Berkeley Laboratory of the University of California, USA. Due to its outstanding advantages compared to previous queue management algorithms, RED has been widely installed and deployed on the Internet. The most fundamental point of their work is that the most effective place to detect congestion and react to it is at the gateway or router. Source entities (senders) can also do this by estimating end-to-end delay, throughput variability, or the rate of packet retransmissions due to drop. However, the sender and receiver view of a particular connection cannot tell which gateways on the network are congested, and cannot distinguish between propagation delay and queuing delay. Only the gateway has a true view of the state of the queue, the link share of the connections passing through it at any given time, and the quality of service requirements of the traffic flows. The RED gateway monitors the average queue length, which detects early signs of impending congestion (average queue length exceeding a predetermined threshold) and reacts appropriately in one of two ways: − Drop incoming packets with a certain probability, to indirectly inform the source of congestion, the source needs to reduce the transmission rate to keep the queue from filling up, maintaining the ability to absorb incoming traffic spikes. − Mark “congestion” with a certain probability in the ECN field in the header of TCP packets to notify the source (the receiving entity will copy this bit into the acknowledgement packet). Figure 3. 1 RED algorithm The main goal of RED is to avoid congestion by keeping the average queue size within a sufficiently small and stable region, which also means keeping the queuing delay sufficiently small and stable. Achieving this goal also helps: avoid global synchronization, not resist bursty traffic flows (i.e. flows with low average throughput but high volatility), and maintain an upper bound on the average queue size even in the absence of cooperation from transport layer protocols. To achieve the above goals, RED gateways must do the following: − The first is to detect congestion early and react appropriately to keep the average queue size small enough to keep the network operating in the low latency, high throughput region, while still allowing the queue size to fluctuate within a certain range to absorb short-term fluctuations. As discussed above, the gateway is the most appropriate place to detect congestion and is also the most appropriate place to decide which specific connection to report congestion to. − The second thing is to notify the source of congestion. This is done by marking and notifying the source to reduce traffic. Normally the RED gateway will randomly drop packets. However, if congestion If congestion is detected before the queue is full, it should be combined with packet marking to signal congestion. The RED gateway has two options: drop or mark; where marking is done by marking the ECN field of the packet with a certain probability, to signal the source to reduce the traffic entering the network. − An important goal that RED gateways need to achieve is to avoid global synchronization and not to resist traffic flows that have a sudden characteristic. Global synchronization occurs when all connections simultaneously reduce their transmission window size, leading to a severe drop in throughput at the same time. On the other hand, Drop Tail or Random Drop strategies are very sensitive to sudden flows; that is, the gateway queue will often overflow when packets from these flows arrive. To avoid these two phenomena, gateways can use special algorithms to detect congestion and decide which connections will be notified of congestion at the gateway. The RED gateway randomly selects incoming packets to mark; with this method, the probability of marking a packet from a particular connection is proportional to the connection's shared bandwidth at the gateway. − Another goal is to control the average queue size even without cooperation from the source entities. This can be done by dropping packets when the average size exceeds an upper threshold (instead of marking it). This approach is necessary in cases where most connections have transmission times that are less than the round-trip time, or where the source entities are not able to reduce traffic in response to marking or dropping packets (such as UDP flows). 3.2.2 Algorithm This section describes the algorithm for RED gateways. RED gateways calculate the average queue size using a low-pass filter. This average queue size is compared with two thresholds: minth and maxth. When the average queue size is less than the lower threshold, no incoming packets are marked or dropped; when the average queue size is greater than the upper threshold, all incoming packets are dropped. When the average queue size is between minth and maxth, each incoming packet is marked or dropped with a probability pa, where pa is a function of the average queue size avg; the probability of marking or dropping a packet for a particular connection is proportional to the bandwidth share of that connection at the gateway. The general algorithm for a RED gateway is described as follows: [5] For each packet arrival Caculate the average queue size avg If minth ≤ avg < maxth div.maincontent .s1 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 15pt; } div.maincontent .s2 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 15pt; } div.maincontent .p { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 14pt; margin:0pt; } div.maincontent p { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 14pt; margin:0pt; } div.maincontent .s3 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 14pt; } div.maincontent .s4 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 14pt; } div.maincontent .s5 { color: black; font-family:"Times New Roman", serif; font-style: italic; font-weight: normal; text-decoration: none; font-size: 14pt; } div.maincontent .s6 { color: black; font-family:"Times New Roman", serif; font-style: italic; font-weight: bold; text-decoration: none; font-size: 14pt; } div.maincontent .s7 { color: black; font-family:Wingdings; font-style: normal; font-weight: normal; text-decoration: none; font-size: 14pt; } div.maincontent .s8 { color: black; font-family:Arial, sans-serif; font-style: italic; font-weight: bold; text-decoration: none; font-size: 15pt; } div.maincontent .s9 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 14pt; } div.maincontent .s10 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 9pt; vertical-align: 6pt; } div.maincontent .s11 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 13pt; } div.maincontent .s12 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 10pt; } div.maincontent .s13 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-d
• Assessment of the Impact of Land Acquisition on Employment and Multi-Employability of People
• Introduction to the Development Process of Dong A Multi-Function Card:

Figure 1.2: IPv4 packet structure

Explanation of the fields:

 Version: indicates the version of the IP protocol used to create datagrams, used for the sender, receiver, and routers to agree on the data schema format. Here the version is IPv4.

 IP header length: provides information about the length of the datagram header measured in 32-bit words.

 Type of service: the 8-bit service type field consists of two parts, the priority field and the service type. The 3-bit priority field is used to assign a priority level to the datagram, providing a mechanism for controlling packets over the network. The remaining bits are used to determine the type of datagram traffic as it travels over the network, such as throughput, delay, and reliability. However, the Internet itself does not guarantee quality of service, so this field is only a requirement, not a requirement for routers.

 Total length: this field consists of 16 bits, it is used to determine the length of the entire IP datagram.

 Identification: 16-bit identification field. This field is used by the host to detect and group fragmented packets. Routers will fragment datagrams if the packet's maximum transmission unit (MTU) is larger than the MTU of the transmission medium.

 Flags: contains 3 bits used for segmentation control, the first bit indicates to the routers to allow or not allow packet segmentation, the 2 low value bits are used for segmentation control, combined with the identification field to identify the packet received after the segmentation process.

 Fragment offset: the network information about the number of times a packet is fragmented, the size of the packet depends on the underlying transmission network, that is, the packet length cannot exceed the MTU of the transmission medium.

 Time - to - live: is used to prevent packets from looping on the network. It acts as a countdown timer, preventing packets from taking too long on the network. Any packet with a time to live of 0 will be discarded by the router and an error message will be sent to the station that sent the packet.

 Protocol: This field is used to identify the next higher layer protocol that is using the IP service in numerical form.

 Header checksum: the header checksum field is 16 bits long, calculated

calculated in all fields of the IPv4 header. When a packet passes through routers, the fields in the header may change, so this field needs to be recalculated and updated to ensure the reliability of the routing information.

 Source Address - Destination Address: used by routers and gateways to route data units, always accompanying packets from source to destination.

 Option and Padding: variable length, used to add selection and filling information to ensure data starts within 32 bits.

1.3.1.3. IP fragmentation and data consolidation

The IP protocol must always have algorithms for dividing and merging data when implemented. Because each datagram is specified with a maximum allowable frame size on a point-to-point connection, called the MTU. When passing through different networks with different MTUs, the packet will be divided according to the MTU value of that network. Determining the MTU of a network depends on the characteristics of the network so that the packet is transmitted at the highest speed.

During the journey from source to destination, a datagram may traverse multiple networks. Each router unpacks the IP datagram from the data frame it receives, processes it, and then encapsulates it in another data frame. The resulting datagrams are numbered for later reassembly. The format and size of the received data frame depend on the protocol of the physical network the data frame travels over. If IP needs to transmit a datagram larger than the MTU, it sends the datagram in fragments, which are reassembled at the receiving end to return to the original state.

When fragmented, most fields are repeated, with only a few changes, and each fragment is further fragmented if it encounters a network with an MTU smaller than its size. Only the destination host has the ability to reassemble the fragments. Since each fragment is processed independently, it can traverse many different networks and nodes to reach its destination.

1.3.1.4. IP Addressing and Routing

Address:Each station in the network is identified by a unique number called an IP address. IP addresses are used in the network layer to route packets through the network. Due to the different organization and size of subnets in the internetwork, IP addresses are divided into classes A, B, C, D, E.

Routing in the Internet:Routing in a packet-switched network refers to the process of selecting a path to send a data packet through the system. A router is a component that performs the routing function. Routing creates a virtual network consisting of multiple physical networks that provide packet delivery services in a connectionless manner. There are many different protocols and software used for routing. The selection of a channel for a packet is based on two criteria: the state of the nodes and links or the distance to the destination (the length or number of hops on the path). Once the distance criterion is selected, other parameters such as: delay, bandwidth or packet loss probability ... are taken into account when selecting a route.

1.3.1.5. IPv6 packet structure

The world is facing a shortage of IP addresses for network devices, the 32-bit address length is not enough to meet the explosion of the network. In addition, IPv4 is an old protocol, not meeting the new requirements of security, flexibility in routing and traffic support. The IPv6 Forum was started in July 1999 by 50 leading Internet service providers with the aim of developing the IPv6 protocol, which is designed to include functions and formats that are more advanced than IPv4 to address the problem of improving the quality and security of the Internet. IPv6 is especially important as mobile computing devices continue to participate in the Internet in the future.

Due to the changing nature of the Internet and commercial networks, the IP internetworking protocol has become obsolete. Previously, the Internet and most TCP networks provided support for relatively simple distributed applications such as file transfer, mail, and remote access TELNET. However, today, the Internet has increasingly become a medium and application-rich environment, led by the World Wide Web (www) service. All of these developments have far surpassed the ability of IP to meet the functions and services. An internetworking environment needs to support real-time traffic, flexible congestion control schemes, and security features that IPv4 currently does not fully meet. Figure 1.3 illustrates the IPv6 packet structure.