Improving Video Over Wireless Network Performance

Overview This article describes how to improve video performance over wireless. Many companies are using various technologies today in search of new video content such as video streaming, webcasting, video conferencing and web conferencing. YouTube services continue to be popular and you use more than the width of banda as more and more companies are using video for training purposes and marketing. Google translation service can now convert the text, making video-based English text available in other countries as well. Keep in mind that with the proliferation of corporate VPN security purposes, employees may use wireless at work seamlessly at home or in a public network. They can access the same video services from anywhere. This is why access is so popular today and the need for infrastructure wireless video performance.The current grade 80.11a / g wireless access point is easily flooded when several clients start downloading large files, and running video applications. The best way to ensure acceptable performance video is now the wireless standard 802.11n. According to a forecast study for Cisco, the number of wireless devices will exceed wired devices on the Internet by 2015, accounting for 54% of IP traffic. In addition the video traffic will account for 90% of consumer Internet traffic 2015.Video Basic Video and voice are real-time traffic flows are naturally sensitive to network congestion that causes latency (delay). Video has both a date and an audio component. It should be noted that the same performance metrics considered as loss, jitter, latency, and packet voice and video traffic impact of the Internet and corporate network. The packet loss has a greater effect on the video, while the latency affects the voice much more. Ensure service levels for specific videos on the network may result in QOS implementation, increasing the bandwidth of the network, changes in network design and equipment changes. All these improvements are for the purpose of making the network "video ready." More and more companies use web conferencing, webcast and video conferencing for meetings and for training purposes. Colleges use it to offer courses as well. This is a very effective tool to reduce travel costs costs.Types VideoIt company is worth to discuss the various types of video services popular today and where, from a network perspective, consumers in the content source. Notice how the majority of services are on Internet.In live streaming video on the internet and broadcast television business webcasts usually delivered to your desktop.Web conferencing to the desktop with the applications they need, such as Skype and Go, a popular service Meeting.Video conferencing service that runs to and through the corporate network with Cisco TelePresence equipment, and companies seeking Polycom.Progressive as Tandberg and download YouTube videos for companies looking like desktop.Video broadcast multicast streams from one to many Netflix video as ricerca.Video PerformanceH.323 defines a set of protocols for audio and video traffic, including H.264 and G.729 protocols. It is a framework for developing multimedia applications on a corporate network. The G.729 protocol is a popular audio compression codec for audio traffic at 8 Kbps, with a delay of 10 ms. The H.264 video codec standard is the latest video compression standard adopted. It specifies 24, 30 and 60 frames per second (fps) for high definition (HD) video conferencing with compression from 1.5 Gbps to 4 Mbps of video traffic at a resolution of 1920 x 1080 and 30 fps.It is important to understand the performance metrics that affect video performance, including packet loss, latency, jitter and throughput. Video is sent as a steady stream of traffic counter data traffic that can be analyzed as email transmitted with some delay and have no significant effect on the level of service. Congestion is the core symptom of a network that is busy and network performance problems. The queues are committed during times of increased network activity. This causes an increase in latency, jitter, packet loss, throughput and decrease packet retransmission. The execution quality of service (QOS) sometimes actually cause data packets dropped to preventDefault voice / video packet loss. The data packets are then retransmitted with a certain delay. The following defines these standards metrics.Latency sector performance: Amount of time for a packet to travel from source to destinationJitter: Amount of change in average latency of each packet loss package: Percentage of lost packets from the source destinationThroughput: the average number of packets sent during a given period of time each video service requires different amounts of bandwidth. Some search services such as video conferencing are the most affected by an increase in latency, jitter and packet loss of desktop applications. Acceptable performance for video conferencing, packet loss should not exceed 1%, 30 ms jitter and a one-way latency of 300 ms (150 ms latency for video conferencing high definition resolution). When these thresholds are exceeded may worsen the picture. Requirements of bandwidth for video are linked to the specific type of service, the amount of resolution and frames per second. For example, a standard resolution of 704 x 576 video at 30 frames per second requires 768 Kbps - 1 Mbps of bandwidth, while a high-definition (HD) resolution of 1080 x 1920 at 30 fps requires 4 Mbps to 12 Mbps desktop search services, such as streaming video and web conferencing have the bandwidth requirements lower than those of video conferencing, but the same problems of loss of latency, jitter and packet affect video performance. And with all the services, you must add an average of 20% additional bandwidth overhead for Ethernet and IP protocol processing.Video Quality of Service (QOS) Implementing Quality of Service (QoS) on a corporate network is an end-to -end process, starting with the source video stream. Video conferencing end points are often connected to a switch board company in the desktop, while streaming video is based on the Internet. The process involves implementation of any QOS traffic priority for the privileged service. Considering videoconferencing, Cisco 3560 and 3750 access switches are often used on board for connecting video devices. The second layer frame of data has a header with 3 802.1p bits that can be set to eight different classes of service (CoS) values ​​from 0 - 7 For example, video is assigned CoS of 4 while the voice packets are assigned CoS of 5 and the highest number gets a better service. CoS high priority data is often assigned to 2.DSCP is a layer 3 protocol used to specify QOS various types of service (ToS) classes for data, voice and video traffic. DSCP values ​​are layer 3 and are examined as a set header in the first 6 bits of the IP Precedence field of IP. The recommendation of Cisco best practices is a video for the marking of DSCP AF41. The data traffic is assigned a lower priority than AF21 investigation, such as the entry is assigned a higher priority to DSCP EF. The video traffic is classified using access lists that define a class map and video traffic for video that is not defined in the access-list matches and points to a specific policy map. The political map is the DSCP traffic videos and the DSCP value is assigned to a queue. Class of Service (CoS), packets can be set with a political map, however, is often marked in the access switches with SRR and WRR with the distribution / core switches.Shaped Round Robin (SRR) is a hardware-based technique for distributed queuing with access switches. Allows SRR layer 2 class of service (CoS) and Layer 3 (TOS) mapping code. The layers of distribution and core switches typically have Cisco 6500 and using Weighted Round Robin (WRR) queuing hardware. WRR is the same idea but the tail architecture is a bit 'different and only layer 2 class of service values ​​are mapped to the routers are distributed queues.WAN with Low Latency Queuing (LLQ) and Class Based Weighted Fair Queuing (CBWFQ), which assigns traffic video the high priority queue, with a specific percentage priority tested to 15%. Guarantees that all traffic video obtain 15% of the bandwidth of the link. For example, a circuit of 1 Gbps wants to allocate Metro Ethernet 150 Mbps of bandwidth for video traffic less protocol overhead. Corporate WAN links as a best practice should never exceed about 33% of the available bandwidth for all voice and video traffic. That leaves room for protocol overhead and packet data. Data traffic will degrade performance, as the packets are discarded and video traffic QoS becomes less effective.Desktop applications use the same tools QOS but the internet company and the wireless network in the design factor. Moreover, the public wireless network you happen to use the video affects the overall network performance. The bandwidth of your home Internet and congestion affects performance as well as any points of congestion in the network. The wireless network is in most cases in which particularly degrades video performance of a thesis describing the public network.Wireless 802.11b industry standard wireless protocols currently standard wireless deployed.80.11bThis approved in 1999, specifies a maximum data transfer rate data of 11 Mbps using the 2.4 GHz unlicensed band in the United States. The band experimented with a lot of interference from commercial devices that use this frequency. The standard in the United States allocates 11 channels with a bandwidth of 80 MHz to 5 MHz per channel. The United States assigns 3 of non-overlapping channels 1, 6 and 11 with a distance of the center frequency of 25 MHz per channel. The modulation scheme is used with 802.11b Direct Sequence Spread Spectrum (DSSS) with CCK with features that minimize the effects associated with interference. The 802.11b data rates further include 1, 2 and 5.5 Mbps.802.11gThis wireless standard approved in 2003, specifies a maximum data transfer speeds of 54 Mbps using the same 2.4-GHz band as 802.11b. The 802.11g standard is popular with a higher throughput and better coverage. The same problems occur instead interference with the 2.4 GHz band The 802.11g is compatible with standard 802.11b and assigns the same channels 11 with 1, 6 and 11 as non-overlapping. The modulation scheme used with 802.11g is OFDM specifies that the data rates higher. Further 802.11g data rates include 1, 2, 5.5, 6, 9, 11, 12, 18, 24, 36 and 48 Mbps.802.11aThis wireless standard was approved in 1999 Definition of a maximum data rate of 54 Mbps using the 5 GHz unlicensed band in the United States. The advantage of 802.11a is higher throughput, but the cell coverage is smaller and additional access points will require the same coverage for 802.11g. There is less interference from devices tested, such as cordless phones, Bluetooth devices, microwave ovens and commercial devices that use the 2.4 GHz band there are 23 non-overlapping channels, with the current specification 802.11h. Some Cisco devices support both 2.4 GHz and 5 GHz transmitters on the same access point. The modulation scheme is used with 802.11a OFDM, with higher data rates and minimizing the effects of noise. Each country specifies the number of channels and frequencies at 5 GHz allows band.802.16This is a (MAN) metro wireless standard that provides wireless access at home and seamless business customers from anywhere. The line of sight of the specific technology a distance of about 27 km and speeds of up to 120 Mbps point-to-multipoint specification operates in the 10-66 GHz. There is a specific 802.16a with network topologies and not the line of sight with licensed and unlicensed frequencies from 2 GHz and 11 GHz with a speed of 70 Mbps The main problem with the use of frequencies without a license any implementation is the MAN 'interference from similar devices.802.11nThe new 802.11n wireless standard approved in 2009 defines the speeds much faster data transfer of 300-600 Mbps and 1000 Mbps network switch from the access point to increase the throughput from the client to access point to an access point and network switch. It operates in both bands at 2.4 GHz and 5 GHz with effective new performance improvements examined as Multiple Input Multiple Output (MIMO) channels and access points are less efficient bonding.Wireless contended essentially a style hub with shared media device broadcast domain pot. Contrast, with an Ethernet switch that has Cisco 100/1000 Mbps of bandwidth per port and the segmentation broadcast with VLAN. The switch uses a much more effective way of access media contention scheme of wireless access points. The wireless network uses an older less efficient access to multiple carrier sense collision avoidance (CSMA / CA) process to manage client access to the network. The effect of CSMA / CA is greater bandwidth utilization, packet loss and retransmits packets with these shared resources. In addition there are problems with the standard wireless 2.4 GHz-band interference and multipath fading signal that occurs when the signal is distorted by the curves of the building or structure. From a practical point of view 15-25 wireless client can be associated with a single access point at any time and maintain good performance. This of course changes as more video and broadband applications are used. The 802.11n can support customers who run simulataneous live video streaming with 14 of them run high definition video streams.Data Distance FrequencySo rate and now I know there's warp speed with the old wireless. Data rate (speed) and performance metrics decrease as wireless clients move further away from the access point. Beyond an average of 50-60 meters, the speed decreases and the latency, packet loss and the increase in jitter. The deterministic wireless network site survey and how many mines where access points should be distributed Sun each cell (defined coverage area) has a signal strength with 54 Mbps coverage area can be extended with more powerful directional antenna . For example, these are generated approximate indications of distance, speed and frequency for the access point Cisco 1240AG indoors. Note the distance 802.11a is half that of a kind Radio 802.11g, however, this evaluation was stronger with a 3.5 dBi antenna.802.11a (5 GHz): 54 Mbps to 60 ft - 80 ft with 3.5 dBi omni antenna802.11g (2.4 GHz): 54 Mbps to 80 ft - 100 ft with 2.2 dBi dipole antennaAs speed data network increases the flow rate decreases effective. Customers who want a maximum continuous banda will need to deploy more access points to design. The increase of the transmission power will actually decrease the capacity of the network at higher rates of data, increasing the speed range with lower data rates examined as in the case of 802.11g. The problem is with the transmission power greater, decreases the sensitivity of the receiver with the carrier of a process called magnitude error. This does not apply to the wireless client, where the transmission power should be set at maximum to obtain the best results. The length of the wireless network or the maximum distance is about 100 meters from the client to access point, and drawings wired Ethernet to 100 meters from the access point to switch. The project campus may be extended with additional switch - switch connectivity of course.Wireless Specifies the maximum data throughput, however, that it is not a practical value. Mixed environments examined how the throughput is reduced for both 802.11b and 802.11g clients on the same network segment. As mentioned the client 802.11b and 802.11g are compatible and can associate with the access point using the same 2.4 GHz spectrum. Throughput for 802.11b is about 6 Mbps, however, that varies with the type of antenna, the distance from the access point and the transmission power. Configure the Access Point 802.11g 54 Mbps for customers and the basic 11 Mbps for 802.11b clients. That prevents the access point to operate at less than 11 Mbps Some access points can operate with dual-band 802.11a and 802.11g, however, are separate logical networks and wireless site must have a separate investigations. The access point 802.11a uses the frequency band of 5 GHz As wavelength range of frequency increases the network decreases. The design with 802.11a covers the distance much smaller than 802.11g with transmission data. The higher frequency (5 GHz), the signals do not pass through the structure of the building as easy as lower frequencies.These are some average values ​​of throughput of the bandwidth and the associated wireless standards. From a practical point of view all 24 channels will not be available with the access points 802.11h 802.11a standard because of interference of the channels overrun. Note the effect of mixed wireless environment equipment tested 802.11b / g on the same network and decrease speed. This occurs as well when there are access points with 802.11n access points older in the same network.802.11b - 6 x 3 channels802.11g Mbps - 22 Mbps x 3 channels802.11b / g - 8 Mbps x 3 channels802. 11a - channels802.11n 25 Mbps x 21 - 150 Mbps x 21 Mbps/300 channelsDecreasing the transmission power of an access point to minimize the interference channel. The effective range can be extended with network access points, repeaters, increasing access point power transmission or adjusting the position of the access point. Using a higher antenna gain on the access point is an option. Cisco access points have a lot of options for deploying antennas with higher gain and sensitivity. Note: you must reduce the length of the cable antenna. On cabling antenna attenuates the signal. Some countries restrict the access point transmitting power setting.RF PropagationAs said signal attenuation at high frequencies is worse. There is however a lot of environmental factors that distort, bend and to minimize the power of the signal. The result is something called multipath fading in which a signal takes many paths to a destination. These are some examples • Diffraction -. Signal drop due to the building structure • refraction angles - environmental factors like humidity can cause the signal that seek to break Reflection • - water, glass or any smooth surface can bounce a fade or distort the signal • Absorption - Absorption of the signal structures (trees) • EMI interference - cordless phones, microwave ovens, electric motors, Bluetooth devices fade margin is the amount of power that the receiver sensitivity can be reduced while maintaining acceptable network performance. This is a factor with the distribution outside of bridges with wireless point to point topologies examined the buildings on campus. Problems with rain fade and know the signals fade margin will avoid performance problems. Polarization is the orientation of the pattern radiated by the antenna as a key and must match the transmitter antenna and receiver. The most often used with antenna polarization access point is linear. Antenna capable of transmitting video horizontally or vertically polarized signal.Improving wireless performance when it comes to requirements for bandwidth and various video services, it is important to note that a wireless network will always need much more width of banda than your corporate LAN or Internet connection at home for the same video service. An example is streaming high definition video live where the effective wireless bandwidth required is much higher than the home LAN or Cable / DSL Internet connection. The internet connection at home would require 500 Kbps - 1 Mbps This is not a problem for the cable to the Internet from home, where the download speed is 10 Mbps on average. The wireless access network with multipath fading and contention problems are not as efficient and would use at effective bandwidth of 5-10 Mbps. Also, note that the packet loss affects the performance of video over wireless latency and jitter, but most of all parameters can be improved with the following improvements.1 recommended. Distribute the new 802.11n access point and client AdaptersThe new 802.11n wireless access point is now rated at 300 Mbps with the new feature enhancement. This is 6 times faster than the nearest standard 802.11g. Deploying 802.11n in 5 GHz band and has 21 non-overlapping channels available as well. Which allows higher data transfer rates for coverage. The new enhancements include multiple input multiple output (MIMO), channel bonding, block acknowledgment MAC, and payload optimization and QOS priority unicast traffic classes.MIMO Explained802.11n uses multiple input / output antennas on the access point and wireless client to increase the data rates of decrease and retransmits and packet loss. The access point and clients can send traffic flows at the same time increasing the amount of data and extension of the range of the network (distance). The current most popular Cisco 1250 AP uses what is called a 2T x 3R MIMO. This transmitting antenna 2 is on the access point and three receiving antenna on the client. The best results occur when all clients using 802.11n wireless adapters and access points are all 80.11n without a mixed environment of 802.11b / g access technical BondingThe points.Channel hours of channel bonding allows the combination of two non-overlapping channels at 5 GHz required to send data at 2x the speed of standard data for a theoretical 300 Mbps In practice, the average rate data at 180 Mbps and 140 Mbps has been tested for streaming video. This is quite impressive comparison with 802.11g average speed of 22 characteristic OptimizationThe Mbps.Payload packet payload optimization or aggregation is basically put more data in each packet sent resulting in more effective use of transport blocks access points average. MAC AcknowledgmentPrevious required that each MAC packet-level package MPDU, each of which has recognized with ACK to. The new 802.11n standard now uses a single block ACK to acknowledge multiple MPDUs. This decreases the amount of protocol overhead and less bandwidth for unicast traffic required.Multicast video over wireless networks presents a particular problem with the wired world that has no multicasting. Thurs wireless access points do not support multicasting, however, 802.11n can now convert streams via multicast to unicast wireless clients to level 2.2. Structure Network access points without wires must always be connected to a 100 Mbps port full duplex access points 802.11n must be connected to a 1 Gbps or 10 Gbps switch port end points video must be connected to the neighboring distribution layer and a linecard less busy. The end point equipment video source can be located at the periphery of the network, but you must select a switch with all the performance characteristics and preferably located in the datacenter. Multiple wireless SSID should always be defined to segment traffic and VLAN assigned to match the same VLAN scheme implemented on a design hierarchy network.Use wired with all new implementations wireless / wired network where possible and spread across multiple access points and connect the switches instead of a single switch. Consider doing a little 'performance monitoring of the network to eliminate the inadequacies of the media. For example, a switch with a port that is gigabit uplinks to a switch with a 100 Mbps addition WAN circuits are very often the slowest link in compliance with the infrastructure switch.Avere a real network of wireless observation site done for each banda to minimize signal overhead and optimize the client adapter copertura.Distribuire internal rather than external style USB to your laptop for the best prestazioni.Quando 802.11a/b/g access points are distributed (mixed environment) with 802.11n access points, it is better to assign access points to 802.11n clients for the 5 GHz band, where there are more non-overlapping channels and less interferenze.Utilizzare all 802.11n access points and clients, where possible, instead of mixed environments and at least 2T x 3R x 2S flows spaziali.Utilizzare the additional access points for coverage area with the standard 5 GHz 802.11n for higher data transmission speed, range (distance), the number of customers rete.Distribuire and availability of more powerful extended range antennas to increase data rate and gamma.Pulire any problems with sub-optimal routing rete.Considerate on the distribution of the WLAN controller WLC 4400. This requires a firmware upgrade on all 1100 and 1200 series autonomous access points, however there are advantages such as looking for advanced management RF.Terzo End to End Quality of Service (QOS) Any good quality of service delivery must take into account both wired and wireless QoS techniques to ensure end-to-end performance. The Wired QOS has already been discussed here with Shared Round Robin (SRR) and Weighted Round Robin (WRR) queuing on the hardware switch. As well there is Low Latency Queuing (LLQ) and Class Based Weighted Fair Queuing (CBWFQ) deployed on the WAN router. CoS and DSCP packet marking is used to prioritize specific traffic types for preferential queuing. Wireless is now Wireless Multimedia Extensions (WMM), which classifies traffic into four categories depending on the type of traffic. These include voice, video, best effort and background. This set provides a guaranteed level of service for video traffic during periods of network congestion.The layer 2 data frame from the switch where the field has an 802.1p class of service (CoS) bits. The access point that examines code field and traffic with a specific setting CoS assigned to the queue. The tail of voice traffic is the highest priority queue and the queue is served first video and data traffic. All wireless clients that do not use VoIP will prevail the first video. Although note that the best effort queue 3 has a CoS of 0 tail that is quiet higher priority than the background traffic. Cisco Video Stream improvement at the application level allows the assignment of a priority for streaming video traffic according to an assigned VLAN or SSID for preferential queuing.Access Point Priority Queuing queue 1: traffic jams Voice CoS = 6.7 2 = 4.5 video traffic queue CoS 3 Best Effort (transactional data) = 0.3 CoS queue 4: Background Traffic (email) CoS = 1.2 Call admission control is a type of QOS which limits the number of video sessions to avoid oversubscription of priority queue at switches and routers. The use of a service gatekeeper controls the number of video sessions and additional sessions depending on the setting of Deny banda tail. The priority queue is configured with enough bandwidth for a specific number of sessions and any requests for additional sessions are denied if it exceeds the tail size.4. BandwidthAs said, making an evaluation of the performance of the current network to identify where the additional bandwidth is needed. The company is the most common source of problems with WAN bandwidth. The prevalence of low-cost, Gigabit Metro Ethernet circuits make today is a great opportunity to deliver on the company network.Copyright Shaun Hummel 2011 All rights reserved [EXTRACT] Overview This article describes how to improve video performance over wireless. Many companies use different technologies of today, video content such as video streaming, webcasting, videoconferencing and Web conferencing YouTube and services continue to be popular with bandwidth increasing, because companies are using video for training purposes and marketing . Google translation service can now convert the text, what the British-based video text and other countries. Note that with the proliferation of corporate VPN security purposes, employees in the workplace can be as easy access to your home or use the public network. You can use the same video services accessible from anywhere. Because access is so popular today and the need for video-grade wireless infrastructure performance.The current 80.11a / g Wireless Access Point is easily overwhelmed when you start downloading multiple clients to run large files, and video applications. The best way to ensure acceptable performance video is now the wireless standard 802.11n. According to a forecast from Cisco study, the number of wireless devices, the devices on the Internet via a crossover cable by 2015 and 54% of IP traffic. In addition to video traffic is 90% of internet traffic from consumers 2015.Video basic video and voice traffic is real-time account of the nature, causes that are sensitive to network congestion, latency (delay). Video has both a date and an audio component. It should be noted that to record the same performance as jitter, latency, packet loss and throughput of video traffic and voice over Internet and corporate networks. Packet loss has a greater effect on the video during latency voice influenced much more. Ensure service levels for specific videos on the network may include the QoS implementation and increases the bandwidth of the network changes the network design and equipment changes. All these improvements are for the purpose of the network "video ready." Companies are increasingly using web-conferencing, webcasts and video conferencing for meetings and for training purposes. University used to offer courses as well. This is a very convenient tool for business costs.Types VideoIt worth discussing different types of video services more popular today, and where, from a network perspective, to reduce the source of content for consumers. Notice how most of the services of Internet video streaming over the Internet from companies sind.Live webcast and TV shows in general conference Desktop.Web to desktop applications such as Skype and go to the very popular Dienst.Video conference service provided by meetings and through the corporate network with Cisco TelePresence and equipment from manufacturers such as Tandberg and Polycom video download läuft.Progressiven from companies such as YouTube to video multicast Desktop.Broadcast from one to multiple video streams, as Netflix.Video PerformanceH.323 defines a set of protocols for audio and video traffic, including H.264 and G.729 protocols. It is a framework for developing multimedia applications on a corporate network. The G.729 protocol is a popular audio compression codec for audio traffic at 8 Kbps, with a delay of 10 ms. The H.264 video codec standard is the latest video compression standard adopted. There are frames 24, 30 and 60 per second (fps) for high definition (HD) video conferencing with compression of 1.5 Gbps of video at 4 Mbps at a resolution of 1920 x 1080 and 30 fps.It important in order to understand the performance metrics that affect video performance, including packet loss, latency, jitter and throughput. The video is a steady stream of traffic as opposed to the traffic like e-mail that can be transmitted with some delay, and have no significant impact on service levels sent. Congestion is the core symptom of a network that takes advantage of experience and network performance issues. The tails are more frequent during periods of increased network activity. This results in increased latency, jitter, packet loss, a lower yield and the retransmission of packets. Implementing Quality of Service (QoS) is in fact at times lead to the fact that to prevent the data packets stored in the voice / video packet loss. The data packets are then retransmitted with a certain delay. Under the metrics.Latency performance standards in the industry: The time for a packet to travel from the source to destinationJitter: height of the average variation in the latency of each percentage of packet loss packets, discarded packets from the source destinationThroughput: the average number of packets sent during a certain period of time each video service requires different amounts of bandwidth. Some services such as video conferencing is more influenced by an increase in latency, packet loss and jitter as desktop applications. Acceptable performance for packet loss video conferencing, should not exceed 1%, jitter of 30 ms and a one-way latency of 300 ms (150 ms latency, high-definition resolution video conferencing). If these limits are exceeded, the image may deteriorate. Requirements of bandwidth for video are connected to the specific type of service, the level of resolution and frames per second. For example, a standard resolution of 704 x 576 video at 30 fps requires 768 Kbps - 1 Mbps of bandwidth, while a high-definition (HD) resolution of 1080 x 1920 at 30 fps requires 4 Mbps to 12 Mbps Services desktop such as streaming video and Web conferencing are the bandwidth requirements lower than those of video-conferencing, but the same problems of loss of latency, jitter and packet affect video performance. Furthermore, with all the services you need to add an average of 20% additional bandwidth overhead for Ethernet and IP protocol processing.Video Quality of Service (QoS) Implementing Quality of Service (QoS) on a corporate network, an end to terminate the process flow from the source video. Videoconferencing endpoints is often connected to a switch board stops, while the streaming video on the desktop via a web browser. The implementation process involves any traffic prioritization QOS for a preferred service. With videoconferencing, Cisco 3560 and 3750 edge switch access are often used to connect video devices. The second layer frame of data has a header with 3 802.1p bits that can be set to eight different classes of service (CoS) values ​​to be 0-7 Assigned as video-CoS of 4, while the voice packets are assigned CoS of 5 and the highest number gets a better service. Data is assigned high priority CoS 2.DSCP is often a Layer 3 QoS protocol used to specify different types of service (ToS) classes for data, voice and video traffic. DSCP values ​​are layer 3 and are as such in the first 6 bits of the IP precedence field of IP header. The best practice recommendation for the labeling of Cisco Video is a DSCP AF41. Traffic is a lower priority as assigned as AF21, while a higher priority is assigned to Voice DSCP EF. The video traffic with access lists, video traffic, and define a map class is divided by the video, a list of access points and corresponds to a map specific classes defined policies. The political map is the DSCP traffic videos and the DSCP value is assigned to a queue. Class of Service (CoS), packages can be a political map, however, is often marked on the access switches with SRR and WRR for the distribution / core switches.Shaped Round Robin (SRR) is a hardware-based switches with access code technology to be adjusted in use. SRR provides Layer 2 Class of Service (CoS) and Layer 3 (TOS) for allocation of code. The layers of distribution and core switches are generally used Cisco 6500 and Weighted Round Robin (WRR) hardware queues. WRR is the same idea, but the snake is only slightly different architecture and Layer 2 class of service values ​​will be displayed in the router queues.WAN with Low Latency Queuing (LLQ) and Class Based Weighted Fair Queuing (CBWFQ), video-on Traffic used to assign high priority queue, with a priority, as a percentage of 15%. In this way all the video traffic to be 15% of the bandwidth connection. For example, a circuit 1 Gbps Metro Ethernet as part of the bandwidth of 150 Mbps to video traffic to less protocol overhead. Corporate WAN connections as best practice should never be greater than about 33% of the available bandwidth for all voice and video traffic. That leaves room for protocol overhead and packet data. Traffic performance deteriorates as dropped packets, and video traffic is less effective.Desktop QOS applications share the same QoS tools, however, use the corporate Internet connection and wireless network-factor in the design. Happen to the public network using wireless network performance affects the entire video. The bandwidth of the Internet connection at home and congestion on the performance and potential bottlenecks throughout the network. The wireless network is usually where the video performance deteriorates approved in the first place on a public network.Wireless They describe 802.11b wireless standard protocols currently deployed.80.11bThis wireless standard in 1999, specifies a maximum transfer rate data of 11 Mbps using the 2.4 GHz unlicensed in the United States. The band undergoes a lot of interference from commercial devices at this frequency. The standard in the United States, has 11 channels, with a bandwidth of about 80 MHz to 5 MHz per channel. The United States offers three non-overlapping channels 1, 6 and 11, with a separation center frequency of 25 MHz per channel. The modulation method used is reduced to a minimum with 802.11b Direct Sequence Spread Spectrum (DSSS) with CCK with properties to the effects of interference. The prices include additional 802.11b 1, 2 and 5.5 Mbps.802.11gThis specified wireless standard approved in 2003, a maximum data transfer speeds of 54 Mbps using the same 2.4 GHz band as 802.11b. The 802.11g standard is popular with higher throughput and greater range. The same problems occur, however, with the banda 2.4-GHz 802.11g is compatible with standard 802.11b has the same 11 channels with 1, 6 and 11, as they do not overlap. The modulation method is used, with 802.11g OFDM, indicating higher speeds. Further 802.11g data rates of 1, 2, 5.5, 6, 9, 11, 12, 18, 24, 36 and 48 Mbps.802.11aThis wireless standard was approved in 1999 to specify a maximum speed of data transfer 54 Mbps the 5-GHz unlicensed band in the United States. The advantage of 802.11a is a higher throughput, however, the range of cells is smaller and additional access points will be needed for signaling the same 802.11g. There is less interference from devices such as cordless telephones, Bluetooth devices, microwaves and commercial units with the 2.4 GHz band there are 23 non-overlapping channels with the current specifications 802.11h. Some Cisco devices support both 2.4 GHz and 5GHz channels at the same access point. The modulation method is used, with 802.11a OFDM, with higher speeds and minimize the effects of interference. Each country sets the number of channels and frequencies that enable 5 GHz band.802.16This a metropolitan area (MAN) standard wireless, consumer and business customers, providing a continuous wireless access from anywhere. The line of sight technology, covers a distance of about 27 miles and speeds up to 120 Mbps point-to-multipoint specification operates in the range 10-66 GHz with 802.16a Is there a specific network connection topologies and non- view with licensed and unlicensed frequencies in the 2 GHz and 11 GHz band with a speed of 70 Mbps The main problem to implement a man with unlicensed spectrum disorders occur within the new 802.11n wireless standard similar devices.802.11nThe approved in 2009 defines the data transfer rate much faster from 300-600 Mbps and 1000 Mbps access point, network switches to increase the throughput from the client to access point and access point for network switches. It works in both 2.4 GHz and 5 GHz with effective new performance enhancements such as multiple-input multiple-output (MIMO) channel bonding.Wireless and access points are essentially fought a less efficient shared-media hub device with a domain broadcast dish. Compare this with a Cisco Ethernet, 100/1000 Mbps of bandwidth per port and the segmentation broadcast using VLAN. The switch uses a conflict far more effective means of access to media such as wireless access point. The wireless network uses an older, less efficient Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) procedures for managing client access to the network. The effect of CSMA / CA is transmitted using the bandwidth, packet loss and packet again increases with this support shared. There are also the Wi-Fi interference problems in 2.4 GHz band and the signal multipath fading signals when turning or changing the structure of the building will occur. From a practical point of view 15-25 wireless client can be associated with a single access point at any time and still good performance. This of course means that further changes in comparison video applications and are used with high bandwidth. 802.11n support in reality, all these customers with simultaneous live video streaming with 14 of them run high-speed video of streams.Data definition, the distance and FrequencySo now know there is no warp speed with the old wireless. To reduce the data rate (speed) and performance parameters, such as wireless clients further away from the access point. Furthermore, an average of 50-60 meters, reduces the speed and the latency, jitter and packet loss. The inspection of the wireless network to determine where and how many points of access should be used so that each cell (service area defined) must be a power of the signal at 54 Mbps The coverage area with a directional antenna can be strong extended. For example, these are approximate nominal distance, speed and frequency for the inside of the access point Cisco 1240AG. Note the 802.11a distance is usually half the size of a radio 802.11g, but this evaluation with a more powerful 3.5dBi antenna.802.11a (5 GHz) was 54 ft Mbps to 60 - 80 ft with 3, 5 dBi antenna802 omni .11 g (2.4 GHz): 54 Mbps ft with 80 to 100 ft with 2.2 dBi dipole antennaAs increases the speed of data transmission network effectively from their area. Customers who want to have a maximum bandwidth continues, more access points used for design. Increasing the transmission power actually reduce the area of ​​the network at higher transmission speed, increasing the flow rate, with data transfer rate lower as the case of 802.11g. The problem is, with transmission power increased, the sensitivity of the receiver is reduced by a process called vector error quantity. This does not, to the wireless clients that should be considered established when the maximum transmission power for best results. The length of the wireless network or the maximum distance is about 100 meters from the client get to the point, and go with the drawings wired Ethernet to 100 meters from the access point. The campus project can be extended with additional switch - switch to specify the connectivity of the maximum data throughput rates course.Wireless, but this really does not matter. Mixed environments such as the throughput is reduced for both 802.11b and 802.11g clients on the same network segment. As clients are not compatible and 802.11b and 802.11g use the same access point with banda of 2.4 GHz spectrum allocated. The flow rate is about 6 Mbps for 802.11g but with the antenna will vary from the access point and power transmission. Configure the Access Point 802.11g 54 Mbps for customers and the basic 11 Mbps for 802.11b clients. This prevents the access point, which is less than 11 Mbps Some access points with dual-band 802.11a and 802.11g work but are separate logical networks, and must have separate wireless inspections. The Access Point 802.11a uses the frequency band of the 5 GHz frequency increases as the network of wavelength decreases. The design with 802.11a covers less distance than standard 802.11g to the same data rates. The higher frequency (5 GHz) signals can not simply pass through the building structure, rather than lower frequencies.These some average values ​​of data throughput and related wireless standards. From a practical point of view, all 24 channels will not be for 802.11h access points 802.11b overwhelmed by interference available channel. Note the effect of mixed environment, wireless devices, such as 802.11 b / g in the same network and decreased productivity. This happens even when access points are equipped with 802.11n access points older in the same network.802.11b - 6 x 3 channels802.11g Mbps - 22 Mbps x 3 channels802.11b / g - 8 Mbps x 3 channels802. 11a - 25 Mbps x channels802.11n 21-150 x 21 Mbps Mbps/300 channelsDecreasing the transmission power of a channel of access point to minimize interference. The effective range is in network with repeater access points will be expanded, better access point transmit power or set the position of the access point. If you have an antenna gain greater on the access point is an option. Cisco access points have a lot of options for deploying antennas with higher gain and sensitivity. Note, it should minimize the length of the antenna cable. The antenna cable as attenuate signals. Some countries limit the maximum transmission power of the access point setting.RF PropagationAs said signal attenuation is worse at high frequencies. There are, however, minimize many environmental factors that bend and distort the signal strength. The result is something called multipath fading, where a signal takes multiple paths to a destination. These are some examples of diffraction • -. Signal decrease due to the construction of angle of refraction structure • - Environmental factors such as moisture can cause the bow to signal • Reflection - water, glass or any smooth surface can distort a signal or fade • absorption jump - Signal structures absorption (trees) • EMI interference - cordless phones, microwave ovens, electric motors, Bluetooth devices, fade margin, the amount of energy, reduces the sensitivity of the receiver, may be acceptable network performance. This is a factor, with the use of bridges with external wireless point to point topology of such buildings in a campus. Problems with rain fade signals and to know the fade margin to avoid performance problems. The polarization is the orientation of the model of the antenna and radiated as a key must coincide with the antenna transmission and reception. The polarization more common with the access point antenna is linear. Antenna capable of transmitting both horizontally and vertically polarized signal.Improving video performance over wireless networks When it comes to requirements of bandwidth and a variety of video services is to be noted, it is important that the wireless network requires a band much more than ever the LAN or Internet in your company for your home videos on the service itself. An example is the high definition live video streaming, which requires the wireless bandwidth is much higher than the actual LAN or home cable / DSL Internet connection. The house requires an Internet connection at 500 Kbps - 1 Mbps This is not a problem, even to the internet at home, where the download speed cable is an average of 10 Mbps wireless network with the conflict of access and multipath problems fading are not as efficient and effective bandwidth used would be 5-10 Mbps. Also, note that no loss of video packets of wireless performance can affect more than latency and jitter, however, all parameters are improved with the following improvements.1 recommended. Spread is the new 802.11n access point and client AdaptersThe new 802.11n wireless access point is now rated at 300 Mbps with the function of the expansion. This is 6 times faster than the nearest standard 802.11g. Deploying 802.11n in 5 GHz band, and it has 21 non-overlapping channels available. This enables higher data transmission rate for each coverage area. The new extensions are multiple input multiple output (MIMO), channel bonding, MAC block recognition, optimization, and payload unicast traffic prioritization and QoS classes.MIMO Explained802.11n uses multiple input / output antennas of access point and wireless client in order to increase data rates and decrease retransmits, and packet loss. The access point and the client can send traffic simultaneously increasing the amount of data and the development of the network (remote). The current most popular Cisco 1250 AP uses a so-called MIMO-2T x 3R. It is two transmit antennas at the access point and 3 receiving on the client. The best results are obtained when using network cards and wireless client 802.11n access points, all without 80.11n mixed environment of 802.11b / g access channel bonding technology points.Channel BondingThe now allows the combination of two non-overlapping channels banda in the 5 GHz data with standard 2x speed data for the sending of a theoretical 300 Mbps In practice, the average rate of data is tested to 180 Mbps and 140 Mbps for streaming video. This is quite impressive when compared to 802.11g speeds averaging 22 feature OptimizationThe Mbps.Payload payload optimization or packet aggregation is essentially putting more data per packet sent to a more effective use to block access transport media.MAC AcknowledgmentPrevious points required for each MAC packet level MPDU has been recognized separately with an ACK packet. The new 802.11n standard now uses a single block ACK to acknowledge several MPDUs. This reduces the amount of protocol overhead and less bandwidth for unicast traffic required.Multicast the video over wireless networks presents a particular problem with multicasting, that the world in the network. Wireless access points do not support multicasting, but 802.11n can now convert the multicast flows for unicast wireless client layer to 2.2. Network Design Wireless Access Point should be connected to a 100 Mbps full-duplex switch port. 802.11n access points must be connected to a switch port 1 Gbps or 10 Gbps. Video endpoints should be closer linked to the level and distribution of a line card less busy. The end-point video source devices to the network edge, as can also be localized, but you should choose a switch with all the features and preferably in the data center is located. Multiple wireless SSID should always assigned to segment traffic and VLANs can be defined to implement the program on the same VLAN-wired network.Use a hierarchical design with each new implementations wireless / wired, and if possible to meet and connect the access points distributed across multiple network switch, instead of a single switch. Here you should delete a part of the monitoring of network performance to the misalignment of media. For example, a switch with a gigabit port coupled to a switch with a 100 Mbps interface uplink. In addition to the WAN circuits are usually the slowest link in comparison with the Infrastruktur.Werfen switch you have done an actual inspection of the wireless network for each band in order to optimize the signal and follow-up report by client adapter minimieren.Bereitstellen internal rather than external style USB to your laptop for the best distribution of Leistung.Bei 802.11a/b/g access point (mixed environment) with 802.11n access points, it is best 802.11n access points and clients with the 5 assigned GHz band, where there are more non-overlapping channels and less Störungen.Nutzen all 802.11n access points and clients, if possible, rather than mixed environment, and at least 2T x 3R x 2S spatial Streams.Verwenden you the access points Additional for each coverage area with 802.11n 5 GHz band for high speed data transmission, range (distance), the number of customers and the availability of powerful antennas Netzwerks.Bereitstellen extended range, erhöhen.Bereinigen to the transmission rate data and problems with a range of sub-optimal routing in the disposal Netzwerk.Betrachten The WLC-4400 wireless controller. This requires a firmware upgrade for all 1100 and 1200 series autonomous access points, but there are advantages, such as advanced RF management FUNCTIONS.3. End-to-Quality of Service (QoS) Stop a good quality of service must include both wired and wireless QoS techniques to ensure the performance end to end. The QOS was here already wired with Shared Round Robin (SRR) and Weighted Round Robin (WRR) queuing to discuss hardware switch. There are also low latency queuing (LLQ) and Class Based Weighted Fair Queuing (CBWFQ) to implement router WAN. CoS and DSCP packet marking is used to prioritize certain types of traffic preferential for a queue. Wireless is now Wireless Multimedia Extensions (WMM), traffic with 4 categories classified by type of traffic. These include voice, video, best effort and background. This provides a guaranteed level of service for video traffic in the network time has set congestion.The layer two data frames from the switch through a field of 802.1p, where class of service (CoS) bits. The access point checks the box and in traffic with a CoS queue on the queue assigned specific setting. The voice traffic is queued, the highest priority queue, all traffic is waiting in the queue in front of the video and data. All wireless clients will not have to prioritize VoIP over the first video. Note that, although best-effort queue 3 has a CoS of 0 to priority queue even greater than the background traffic. Cisco Video Stream mapping application extension in traffic video makes a priority of current or SSID to VLAN mapping for priority queuing point favorite queuing.Access: Coda 1: Voice traffic queue CoS = 6.7 2: Video traffic CoS = 4.5 Queue 3: Best Effort (transactional data) = 0.3 CoS queue 4: Background Traffic (email) CoS = 1.2 Admission Control is a sort of QOS that limits the number of video sessions of oversubscription priority queue to prevent the switches and routers. The use of a service gatekeeper controls the number of video sessions and refused further vertices of the setting of the bandwidth of the tail. The priority queue is enough bandwidth for a certain number of sessions configured, any request for additional meetings may be denied if it is greater than the queue size.4. BandwidthAs mentioned, evaluate the performance of the current network to identify where you need additional bandwidth. The WAN society is the most common cause of problems with bandwidth. The costs and the low prevalence of Metro-Gigabit Ethernet circuits make today is a great opportunity to use it on the company in 2011 Shaun Hummel network.Copyright All rights reserved