Internet Traffic Management

Transcription

1 A Seminar Report On Internet Traffic Management Presented By Prafull Suryawanshi Roll No. 04IT6008

2 Table of Content: 1. Abstract 3 2. What of Internet Traffic? Why worry about Traffic?.5 4. Measuring Internet Traffic..6 a. Motivation b. What can we measure? c. What kind of traffic is it? d. Different approaches in measurement e. Different tools in market 5. Traffic Control and Management 9 a. Types of traffic control b. Internet Traffic Management Products c. QoS and Pricing Issues 6. Conclusion..11

3 Abstract The purpose of this seminar report is to discuss issues related to traffic in Internet. As we know today s computing world mostly rely on Internet for its day-to-day activity. Almost each organization in world use Internet for its operation. But as Internet provides limited resources, there is a sort of competition of accessing resources. It provides traffic in the Internet. If this traffic is not handled carefully then it will result in congestion. So one must consider the facts related measuring and handling Internet traffic. Measuring the traffic of Internet can start this traffic management. Anglicizing of output of previous step may provide good simulation. This further useful to model traffic and use certain ways to provide good traffic management. Traffic management is key for quality of service. So one must consider the importance of work in this field. As in real world traffic inspectors control the vehicle traffic on the roads, same in Internet this work is done by traffic engineers. They control the traffic to provide best quality of service.

4 What is Internet traffic? While discussing the issues of Internet traffic one must clear his concept about Internet traffic. Internet traffic can be defined in number of ways. But in simplest language we can define it as the density of data present in the Internet. In Internet the there are lots of communication devices accessing resources and getting request to carry out there work. Other type of communication devices may busy to respond the request by these devices. So there is lot of information exchange in Internet in form of request, response and control data. This data can produce an huge number of packets in Internet. Transforming such large data may cause load, which results slow down the operations of communication devices. Due to this other devices may get delay in communication activities. This ultimately results in congestion of Internet. This can be simple description of Internet traffic. In other words we can say that Internet traffic is load on communication devices or system. Why worry about traffic? As we travel from one place to other place in metro city, we pass no of roads and turns. Consider that there is some problem on road and you have to wait till that problem clears then you are jammed in traffic. In the same sense, when you send a request it is possible that due to some problem or other requests you have to wait for some time. If no of packets are queuing and waiting in network then it results in traffic. If once traffic created, you must wait till it over, which is definitely not fixed or depend upon current situation. So to deal with this situation, there must be some way to deal with this situation. Internet traffic is dynamic problem. Static solutions are not sufficient. Traffic management required even during overload. And also traffic management required for continuous media. The next whole document is dedicated to measuring the traffic, analyzing it and finding ways to deal or manage it.

5 Measuring Internet traffic Motivation of measurement The basic thing to motivate for Internet traffic measurement is the requirement by service providers and service users. Different tasks like monitoring, debugging, engineering, architecture development carried out by these factors strongly require efficient use of Internet so it ultimately leads to measurement of Internet traffic. To manage the Internet traffic, very first important step is to measure the traffic. There are many reasons to measure network traffic including Making sure things keep working Deciding when more capacity is needed Session times and traffic volumes can provide billing data An improved understanding of what s happening should allow us to improve network performance What can we measure and how? Most network hardware vendors provide some network management capability in their equipment. For example, they may support the Simple Network Management Protocol and implement some of the IETF standard Management Information Bases (MIBs). For example the IP and RMON MIBs provide counts of the packets and bytes flowing through each network interface. These MIBs can be used to monitor the amount of data flowing across an ISP s network links, which is certainly very useful, but it is not enough to give a detailed view of the traffic and the way it behaves. To collect more detailed information one needs to use more specialized methods or tools. This usually means running a measurement program on a host attached to the network, and it may also require the use of specialized hardware such as network interface cards with the ability to measure packet arrival times very accurately. These methods can allow us to measure things like Link behavior - packet loss rate, transit time and jitter (variation in transit time). These properties of the link can greatly affect the service quality as seen by users. Routing topology - how do packets get from A to B, what routes are available at any given time, how stable is the routing. The

6 skitter tool provides a way of measuring this for very large numbers of interconnected hosts. Traffic flows - how many packets/bytes flow, where do they flow from and to? Tools for measuring traffic flows are discussed in below. Basic performance metrics of Internet traffic can be listed as Packet loss Delay Throughput Availability Etc Also there are number of other drivers strongly deals with requirement of measurement are Pricing Service level agreements New services Applications What kind of traffic is it? Every packet in an IP traffic flow carries 'port numbers,' which are used by hosts to determine how to handle the flow's traffic. Some of port numbers are 'well-known,' i.e. they are fixed and they indicate the traffic type directly. Port 23, for example, identifies telnet traffic for every packet in a telnet session. This is not always the case - although ftp has two well-known ports, it may also use other ports. Again, www always uses a fixed port number (well-known port 80, web proxy servers often use others such as 8080), but the http (web) protocol may carry many different kinds of object, e.g. text, image, movie, e-commerce transaction, etc. The last two cases describe traffic information pertinent to the network application generating it. Measuring this would require the measuring system to understand the applications, rather than merely looking at individual packets. I'm not aware of any tools, which can measure application data like this in any general way. A further complication comes from the increasing use of data encryption. If the data part of a packet is encrypted it will not be possible to determine port numbers within it. In such a case one can observe that encrypted traffic is flowing between two hosts, but it is impossible to glean further information as to what kind of traffic it is.

7 Different approaches in traffic measurement Active Measurement of Traffic As name indicates, in this measurement approach users or providers are directly related to the activities to the measurement. There are number of different ways to carry out this measurement like following 1. Injection of probes into network by users and providers 2. Ping and Traceout Path connectivity Round-trip delay 3. User-application performance as seen from hosts Loss Delay Throughput 4. Distribute on measurement servers Probes are spread across mesh of paths through network to check scalability and growth of probe traffic Passive Measurement of Traffic In this approach user is indirectly deal with system using some hardware or software tools. Basically some historical data is used to find the current traffic measurement. The currently used techniques for this type of measurement are as follows 1. Packet monitors This can be achieved by recording packet headers on link It requires unique detail of protocol and architecture studies 2. Router / Switch traffic statistics. Analyzing router or switch, the intelligent devices installed at network, can provide network internal behavior. Using these devices we can get information about Packet drops Counts Flow statistics 3. Server and router logs

8 Measuring Tools These records or logs can perform well work in measuring. They provide summaries of dial session, routing updates or web-server log. There are many tools available in Internet. They are listed according their categories Local Systems o NETSTAT o TCPDUMP o ETHREAL o NTOP Remote (END) System o MIB o IF-MIB o SNMP o MRTG Routers o NETFLOW (CISCO) o LFAP (ENTERASYS) SNIFFERS o RMON o RMON2 o NETRAMET

9 Traffic Control and Management Types of traffic control (traffic_control.pdf) Macroscopic o Accomplished by restricting route topology or connectivity information. o Accomplished through the use of BGP and sometimes IGPs. o BGP implementations have per peer Announce and Accept filters o Filters can consider the route prefix, AS path and other criteria. Microscopic o Controls traffic at the point of forwarding rather than at point of information propagation. o Typically examines (TCP UDP) / IP headers and some times payload. o Firewalls o Intrusion Detection Systems with active response mechanisms. The above types of traffic control or management emphasize on single point traffic control rather considering the whole or entire network. In other words we can say that it is necessary to consider traffic management in distributed IP environment. As we know in Internet the mostly used resources are webservers. At the server site there are number of requests come to server each day. For popular websites this number may reach million or above. As such huge amount of request and response to them may cause traffic at server side. The one possible solution to this problem is creating server farm at server side. Means there are number of servers to provide service to the clients. The challenge presented by the server farm solution is that each server has a unique IP address. This means that users must remember, or have access to, more than one address. It also means that the traffic is not distributed between the servers in an efficient manner. Load balancing devices that manage local traffic, provide the solution to this challenge. When a load-balancing device is installed at a server site, it is assigned a Virtual IP address (VIP). Users access this IP address, and the load balancer routes traffic to the

10 servers in the server farm. Additionally, the load balancer monitors the load on each server, and routes the traffic accordingly. This means that users reference the site through a single URL (IP address) regardless of the number of physical servers that actually exist. In addition, since an intelligent load balancer is employed they access the site in the most efficient manner. Furthermore, unlike the strong server solution, server farms do not have a single point of failure, so if a server goes down, there is another server available for the traffic. The load-balancing device ensures that traffic is not routed to a server that is unhealthy, down or simply saturated with requests. In order to manage the traffic, effectivity of server farm can be improved by distributing servers in server farm in greater distance. This means spread servers physically long distance. To control the traffic for these globally distributed server, local load balancing algorithms cannot work. For it some global load-balancing appliance must be used. The possible work done for this approach can described as 1. Treat the corporate resources as single entity 2. Provide for distributed site fail over and redundancy. 3. Be able to balance load globally based on real time traffic. Internet Traffic Management Products After measuring the traffic and processing the data it is time to use some product or techniques to manage the traffic. The above paragraph already described some types and techniques. Along with it there are number of products present in Internet. They fall in mainly three categories 1. Load balancing switches 2. PC/Server based products 3. Server side agents. QoS and Pricing issues Quality of Service and pricing issues mainly depend on service provided by the ISP. ISP may present at different levels. Internet traffic greatly impact on data, voice, video services. Following traffic characteristics have great impact on SLA (Service Level Agreement).

11 1. Traffic Variations 2. Flow and Sessions 3. Streaming and elastic flows 4. Variable rate traffic streams Conclusion From this paper we can conclude that analysis of IP traffic characteristics and how these impact network performance leads us to question the appropriateness of currently proposed QoS architectures. We also doubt that pricing can be used to control congestion in a commercial setting where the main role of charging is return on investment. For achieving this purpose we must concentrate on proper techniques of traffic measurement and use that data to manage the traffic. Due to these activities it is helpful for corporate users to maintain their service qualities.