Performance Improvement of video based applications in WFQ using Committed Access Rate

Abstract

ABSTRACT In this paper, the video received, IP drop in WFQ is improved using committed access rate (CAR). The committed access rate is used for video and http applications and for WFQ queuing scheme. From results, it has been analyzed that the video received in WFQ shows much better improvement than the conventional. The significant results have been investigated for IP drop in case of WFQ with committed access rate and conventional which are 0.7 and 8.36 packets per second respectively. The result for video received in case of WFQ with committed access rate and conventional is 383.8 and 5.56 packets per seconds. Keywords Weighted Fair Queue, Committed Access Rate (CAR), IP QoS, ToS 1. INTRODUCTION Committed access rate is a method for managing unwanted traffic on the network without affecting the important traffic. CAR set high TOS for video traffic and low TOS for HTTP traffic. WFQ can prioritize the traffic and give the high bandwidth to the video traffic. CAR provides high bandwidth for video applications. CAR defines a rate-limiting feature for policing traffic, which helps managing the network's access bandwidth policy by ensuring that traffic falling within specified rate parameters is transmitted, while dropping packets that exceed the acceptable amount of traffic or transmitting them with a different priority. The input and output traffic on an interface or sub-interface may be selected based on a flexible set of criteria like all IP traffic or all traffic on an interface or based on IP precedence or MAC address or IP Access List, after which it applies the contracted rate limits, which are the parameters for a token bucket algorithm i.e. average rate, normal burst size and excess burst size. Once the packet is determined to be conforming or exceeding its limits the defined conform/ exceed action will be taken. Committed access rate can be used with the IP traffic. It doesn’t work for non-IP traffic like AppleTalk, IPX, SNA, DECNet [1]. CAR is a limiting or policing scheme which consists of certain rules based on attributes such as class of service (COS), data rate, normal burst size and excess burst size which sets a bandwidth limit for specific types of traffic on router interfaces. For example, you can create a policy that limits web traffic to 200 kilobits/sec. This puts a cap on the bandwidth available to that traffic, ensuring that the remainder of the interface’s bandwidth is available to other kinds of traffic. In this example, if web traffic does not fill 200 kilobits/sec, other kinds of traffic can use the unused bandwidth. Packets are dropped if traffic bursts exceed the limit. CAR limiting does not attempt to smooth or shape the traffic flow in the way that GTS or FRTS attempt to do. Because CAR does not buffer the traffic, there is no delay in sending it, unless the traffic flow exceeds your rate policy and it is dropped. One of the main uses for limiting policies is to ensure that traffic coming into the network is not exceeding agreed-upon rates. If the limiting policy for inbound traffic is defined, the traffic can be controlled before it gets into your network at the inbound interface [2]. Traffic policing controls the maximum rate of traffic sent or received on an interface. Based on the results of the token bucket measurement, an action can be configured to mark packets and separate packets into multiple classes or levels of service. Traffic polices provide two key benefits: Bandwidth management through rate limiting: It control the maximum rate of traffic sent or received on an interface. Traffic that falls within the rate parameters is sent, whereas traffic that exceeds the parameters is dropped, or sent with a different priority. Packet marking through IP precedence, QoS group, or DSCP value setting