QoS in VOIP and Other Networks - Report Example

QoS in VOIP and other Networks Student’s Name Institution’s Name Executive Summary This report discusses various techniques that can be applied to ensure high QoS in a Cisco based network system as well as Cisco VOIP system. The paper discusses Implementation of QoS in a simple network, where various techniques are discussed based on Cisco available software algorithms. The discussed techniques include marking and classification, congestion management, congestion avoidance, traffic shaping and policing, link efficiency, signalling, traffic conditioning, and link competence mechanisms. The paper also discusses queue management for high QoS using first-in, first-out queuing (FIFO), custom queuing (CQ), priority queuing (PQ), class-based weighted fair queuing (CBWFQ), and flow-based weighted fair queuing (FBWFQ) techniques. It also discusses on how to ensure QoS in a VOIP system and also in an Ethernet system using various configurations and algorithms. Finally, the paper gives brief summary of the discussion. Table of Contents Introduction 5 QoS with Cisco 5 Implementation of QoS in a Simple Network 5 Queue Management 7 VOIP QoS 7 QoS on Ethernet 8 QoS with Netgear 9 AutoQoS 9 Manual Configuration 10 23.Class-map is a command used to generate a specific class-map, match protocol command is used to match a particular protocol, match cos command is employed o match a particular value of CoS and match dscp command is employed to mach a particular differential service code point (DSCP). A policy-map command is employed to generate a particular policy map, a class command is employed to connect a policy to a particular class map. Set cos command is employed to set a particular CoS value, set dscp is employed to set a particular DCSP value and finally, service-policy command is employed to connect a policy map to an interface (Cisco, n.d.c.). 10 Conclusion 11 Annexes 14 Cisco. (2005). Cisco AutoQoS Q&A. Retrieved October 21, 2012, from http://www.cisco.com/en/US/technologies/tk543/tk879/technologies_qas0900aecd8020a589.html 15 Cisco (2006a) IP application services using Cisco service assurance agent and internetwork performance monitor to manage quality of service in voice over IP networks. Retrieved October 21, 2012, from http://www.cisco.com/en/US/tech/tk648/tk362/technologies_tech_note09186a0080094b26.shtml 15 Cisco. (2006b). Voice quality voip over frame relay with quality of service (fragmentation, traffic shaping, LLQ / IP RTP priority). Retrieved October 21, 2012, from http://www.cisco.com/en/US/tech/tk652/tk698/technologies_configuration_example09186a0080094af9.shtml 15 Cisco. (2007a). ATM traffic management configuring atm per-vc queuing on the MC3810. Retrieved October 21, 2012 from http://www.cisco.com/en/US/tech/tk39/tk51/technologies_configuration_example09186a0080094b39.shtml 15 Cisco. (2007b). Cisco catalyst 3750 series switches. Cisco catalyst 3750 QoS configuration examples. Retrieved 21 October 21, 2012, from http://www.cisco.com/en/US/products/hw/switches/ps5023/products_tech_note09186a0080883f9e.shtml 15 Cisco. (2009). QoS Frequently Asked Questions. Retrieved October 21, 2012, from http://www.cisco.com/en/US/tech/tk543/tk545/technologies_q_and_a_item09186a00800cdfab.shtml 15 Cisco. (2012). Internetworking technology handbook. Retrieved October 21, 2012, from http://docwiki.cisco.com/wiki/Internetworking_Technology_Handbook 15 Introduction 1. Quality of service (QoS) is defined as a network capability to offer improved services to a chosen traffic of network over a number of technologies that include IP-routed network, SONET, 802.1 and Ethernet networks, asynchronous Transfer Mode (ATM) and Frame Relay. The prime QoS goal is to offer priority that includes controlled latency and jitter, dedicated bandwidth, and better characteristics loss. Additionally, it is vital to ensure that priority provision for single or extra flows does not result to failure of other flows. Technologies of QoS give the rudimentary building blocks, which will be employed for applications of future business in WAN, campus, and in networks of service provider (Cisco, n.d. a). QoS with Cisco Implementation of QoS in a Simple Network 2. The simple network architecture initiates the three basic pieces for implementation of QoS. These pieces include QoS marking and identification methods for QoS coordination from one end to another between elements of a network, QoS in a single element of a network, and QoS accounting, management, and policy functions to administer and control end-to-end congestion across a network. In Cisco is implemented by use of QoS ISO algorithms (Cisco, n.d.a ). 3. QoS fundamentally enables one to offer improved services to particular flows. This is accomplished by either increasing one flow’s priority or lowering another flow’s priority. When applying tools for congestion management, one can raise flow priority by serving queuing and queuing in various ways. The queue tool of management employed for avoidance of congestion increases priority by eliminating flows of lower-priority before those of higher-priority. On the other hand, shaping and policing offer flow priority by restricting other flows throughput, when connection efficiency tools restrict large flows to indicate small flows preference. 4. Marking and Classification: marking and identification is attained through reservation and classification. According to Cisco (2008) for one to offer preferred services to a particular form of traffic, the traffics must first be recognized. Then the packet needs to be grouped as marked or unmarked. When the identified packet is unmarked, the classification is based on per-hop traffic, a classification that only pertains to the device which is on, and it is not passed to the subsequent router. This occurs with custom queuing and priority queuing (PQ). If the packets are marked to be used in the entire network, bits of IP precedence can be set. 5. Congestion Management: policing/shaping, link efficiency, queue management, and congestion management tools offer QoS within element of a single network. Due to data, video, or voice traffic bursty nature, the traffic quantity sometimes exceeds link’s speed. At this point router is unable to settle on the right technique to use in handling the situation and thus, tools for congestion management are chipped in to handle the situation. 6. Congestion Avoidance: the algorithm of WRED provides for network interfaces congestion avoidance by offering management of buffer and permitting traffic of TPC to throttle back prior to exhaustion of buffers. This enhances avoidance of tail drops as well as issues related with global synchronization, therefore, maximizing the performance of TCP-based application and network utilization (Cisco, 2008). 7. Traffic Shaping and Policing: traffic shaping is employed to generate a traffic flow, which limits the flow potential of the full bandwidth. This is in most cases applied to prevent the problem of overflow. Shaping is the best way for pacing traffic nearer to 384 Kbps to shun remote link overflow. Traffic beyond the rate of configuration is buffered for later transmission to maintain configuration rate. In policing, traffic that runs beyond the rate of configuration is usually discarded rather than being buffered as it takes place in shaping. 8. Link Efficiency: in most cases, links of low-speed present problems for packets of small size. For instance when a voice packet is behind a very big packet, the voice delay budget would be surpassed long before the packet leaves the router. In such cases, link interleaves and fragmentation permit the big packets to be fragmented into minute packets interleaving the packet of voice. Link efficiency can also be assured by elimination of excess overhead bits. This can be done by use of RTP compression of header that lowers the header to a manageable size (Cisco, 2001). 9. Signalling: Cisco provides QoS management software for IntServ model of IETF. This model contains RSVP, which is a basic mechanism to execute flows admission control in a network. According to Cisco (2008) this technology is best suited in VOIP, where it controls the availability of call resources. According to VOIP configuration, a call can only be completed if all resources required are available, this technique ensures any call getting into the system does not collide with or influence existing calls ‘quality. QoS policy proliferation through BPP is another technique that permits direct signalling the forwarding priority for IP-prefix, AS-path, or autonomous destined packets by use of BGP community list aspect. 10. Traffic Conditioning: traffic getting into a network can be controlled by use of a shaper or policer. A shaper restricts the flow of traffic while a policer imposes a rate-limit to its particular rate by use of buffers. FRTS, GTS, and CAR mechanism can be configured within/without the framework of MQC. 11. Link Competence Mechanisms: voice traffic and steaming video employs the RTP. RTP, UDP, and IP packet headers may be compressed from about 40 down to 8-5 bytes. This preserves a remarkable quantity of bandwidth in the low speed connections cases, and while a big number of streams of media are being support. Additionally, FRF.12 frame fragmentation specification and LFI specification permit fragmentation of big packets of data, interleaving them with packets of RTP, and maintaining low media streams jitter and delay (Cisco, 2006a). Queue Management 12. To avoid tail drop in a queue, it should be ensured that the queues do not get filled up, and there is always a room for packets of high-priority. Additionally, special packets dropping criteria should be allowed, where packets of lower priority are dropped before those of higher-priority. The two techniques will ensure proper management of queues by preventing queues overflow and dropping of packets of higher priority (Cisco, n.d. c). 13. Queuing algorithm is one of the methods used by elements of a network to handle arriving traffic overflow, and to determine various techniques of prioritizing its output connection. The IOS software of Cisco uses various queuing tools to handle this overflow. These tools include first-in, first-out queuing (FIFO), custom queuing (CQ), priority queuing (PQ), class-based weighted fair queuing (CBWFQ), and flow-based weighted fair quieting (FBWFQ). Each algorithm of queuing was created to handle a particular network traffic issue and contains a specific effect on performance of the network (2006a). VOIP QoS 14. A VOIP transmission is said to be comprehensible to the receiver only if voice packets are not dropped, they do not experience excessive delay or suffer from varying delay. To ensure that a VOIP system accomplishes the above, the following standards need to be met: The default codec G.729 needs packet loss to be far lower than 1% to avoid errors that are audible. In ideal situation, VOIP system should not have packet loss. In the second standard, the specification of ITU G.114 recommends end-to-end of one-way delay of below 150 milliseconds for real-time high-quality traffic for instance voice. On the other hand, jitter buffer that is used for varying delay compensation add further to end-to-end delay. These buffers are normally effective only on delay difference of below 100ms and thus jitter need to be minimized (Cisco, 2006b). 15. VOIP can only ensure high voice transmission quality if the packets of voice for both the audio and signalling channels are offered priority over network traffics of other kind. To ensure users obtain an acceptable voice quality level after deployment of VOIP, the traffic of VOIP needs to be guaranteed with certain jitter, latency, and bandwidth requirements compensation. QoS guarantees that voice packets of VOIP acquire the required preferential treatment. Generally, QoS gives improved network services by offering the features such as dedicated bandwidth support, recuperating loss characteristics, managing and avoiding congestion in the network, shaping traffic of the network and by setting priorities of traffic in the network as discussed below (Cisco, 2012). QoS on Ethernet 16. In the multilayer switches, catalyst line is the capability to offer Qos at the second layer. In the Ethernet the frame employs class of service (CoS) in Interlink Switch Link (ISL) and 802.1p at layer 2. Just like precedence of IP, CoS employs 3 bits and maps fairly from the second layer to the third layer and vice versa (Cisco, n.d.b.). To ensure high QoS, switches contain the ability to distinguish frames anchored in settings of CoS, where during differentiation process, frames are placed in varying queues where they are serviced through weighted round robin (WRR) in the presence of multiple queues (Cisco, 2009). This permits every queue to contain different levels of service. In the queue, thresholds of WRED that are similar to the lowest thresholds set in layer 3 WRED are set, and operate as the initial point for the likelihood that a packet is going to be dropped. The figure bellow gives an explanation of how this operates. 17. The two queues apply WRED and WRR techniques by setting two thresholds in each queue. In this case, queue 1 is given settings 4, 5, 6, and 7, while settings 0, 1, 2, and 3are given to queue 2. The first queue is set to obtain 70% time service, while second queue gets 30% time service. When the first queue is 30% full, then, settings 5 and 4 may be dropped. Settings 7 and 6 remain in the queue until the queue is 85% full where they are also dropped. In the second queue, once the queue 20% filled, setting 1 and 0 may be dropped. The 2nd and 3rd settings remain in the queue until it attains 60% where 2 and 3 are also dropped (Cisco, n.d. a). QoS with Netgear 18. In Netgear Company, QoS is applied mostly in VOIP system with an aim of prioritizing voice and video packets to prevent them from being dropped due to prolonged delay. Packets prioritization in Netgear involves three major steps that include classification, marking and queuing. Classification is the procedure of deciding packet’s priority. This is un-standardized process, where decisions are commonly based on either trusting QoS marking contained in the packet header or on a complex criteria set described by network administrator. Marking entails setting certain bits value in the header of a packet indicating the packet’s priority. The bits set and the value used in marking depends on the marking layer and QoS standards used. According to Netgear (2009) there are a number of QoS standards that can be applied in Netgear systems, an aspect that creates a lot of confusion during configuration. Finally, QoS is enhanced through queuing where the packets market with high priority are forwarded first, and in case of network congestion, the system tries as much as possible to maintain packets of high priority in the queue. Netgear systems make independent decision on each packet fate depending on packet configuration. 19. According to Netgear (2009) there is only one standard of QoS used currently on LANs for Layer 2 frames priority marking. This is the standard for IEEE 802.1p that specifies 8 levels of priority known as levels of Class of Service (CoS). In the contrary, there are 3 widespread QoS applied on LAN for packets priority marking at layer 3. They include Differential Services (DiffServ), IP precedence and Type of Service (ToS). Like Cisco, Netgear majors on queue management to maintain QoS in its networks. AutoQoS 20. AutoQoS is a novel technology that lowers operational cost, time and the complexity of QoS. Cisco AutoQoS deployment integrates value-added acumen to operating service software of Cisco Catalyst and Cisco IOS software to manage and provide large-scale deployments of QoS. The Cisco AutoQoS first phase targets deployments of VOIP for clients who wish to deploy telephony of IP, but lack the staffing or expertise to deploy and plan IP services as well as IP QoS. Cisco AutoQoS mechanizes consistent QoS features deployment across Cisco switches and routers. It allows various components of Cisco QoS based on the environment of the network and Cisco recommendations of best practice. With current increased delay-sensitive prominence applications networks deployment, proper configuration of QoS will be required to ensure application of high-quality performance. This assumes a deep understanding of different features of Qos and the difficulties of configuring a number of parameters related to these traits. Cisco AutoQoS assists in overcoming these complexities by configuring the device automatically for Cisco QoS variables and features with the accurate parameters. Subsequently, users can tune Cisco AutoQoS generated parameters to suit their specific application requirements, as desired (Cisco, 2005). 21. Cisco AutoQoS speeds up QoS technology provision and simplifies deployment of QoS over infrastructure of Cisco network. It lowers costs of training and minimizes human error. With AutoQoS-VOIP, a single command can allow QoS for VOIP over every Cisco switch and router. Additionally, the user modifies generated AutoQoS commands/policy through CLI to meet particular requirements. Manual Configuration 22. Cisco QoS is typically configured on novel equipment by use of interface of Modular QoS Command-line (MQC). With MQC, match and class-map commands are used to classify traffic, set, class and policy-map commands are used to define traffic policy and finally, service-policy command is used for policy assignment (Cisco, 2007a.). 23. Class-map is a command used to generate a specific class-map, match protocol command is used to match a particular protocol, match cos command is employed o match a particular value of CoS and match dscp command is employed to mach a particular differential service code point (DSCP). A policy-map command is employed to generate a particular policy map, a class command is employed to connect a policy to a particular class map. Set cos command is employed to set a particular CoS value, set dscp is employed to set a particular DCSP value and finally, service-policy command is employed to connect a policy map to an interface (Cisco, n.d.c.). 24. The example below show how the described commands are collectively applied in a manual configuration. The sample matches all traffics of H.323 and provides it with a EF (Expedited Forwarding) DSCP value router(config)#class-map h323 router(config-cmap)#match protocol h323 router(config)#policy-map h323-policy router(config-pmap)#class h323 router(config-pmap-c)#set dscp EF router(config-if)#service-policy input h323-policy 25. These commands are input manually in the control panel of very router. The greatest disadvantage of manual configuration is routers and switches are configured one at time and thus it can be very tedious and confusing in large network systems (Cisco, 2007b). Conclusion 26. Ensuring a high quality of system performance is a concern to every network administrator. The introduction of QoS by Cisco and other related companies was a great step to improve network and VOIP system, though this cannot be accomplished without addition of extra effort to achieve it. There are various methods that can be applied to ensure QoS in a system. Most of them according to the report are offered by Cisco software in form of algorithm to be applied depending on the set up of the system. The report clearly shows that most available methods of ensuring high QoS revolves around resources management to ensure easy learning and handling of difficult situations. QoS techniques discussed in the report involve software configuration to ensure services are offered as preferred by the network administrator. Although, hardware configuration is not mostly considered, it is important to note that the configuration and algorithm application are dependent on the manufacture of the hardware, and thus, Cisco algorithms and documented configuration only work best with Cisco hardware, though the technology involved can be borrowed by its competitors. 27. Glossary ANI- Advanced Network Initiative – it is a form of network that is capable of large traffic bandwidth support enhancement in a network CAR Tool-Computer assisted reviewing tools: they are software which compares formatting of a text amid two documents. It applies intelligent analysis for differences detection that does not contain similar value in regard to document field and the type. CCM-Cisco Call manager: this is software used for processing VIOP of Cisco to other networks that gives signalling as well as control services of a call to Cisco applications of integrated telephony and applications for third-party. CDR- Call Detail Record: it contains comprehensive information regarding calls running sum charged, the amount billed for every call, as well as call’s origin, route and termination point. Cisco Unity: this is a powerful solution of communication that gives advance services of communication for instance messaging and voice. With Cisco unity one can listen to VOIP check email messages. CM: this is a scheme containing contact, messaging and voice details that permits other schemes to contact them via VOIP. CME-Caller manager Express: it is a VOIP phone call processing tools of management used by several business individuals for it is cheap CMR-Call Management Records: it keeps information regarding streamed audio and video quality of VOIP network call CSS-Content Service Switch: contents copies are temporarily stored on a cache server to the client topologically closer locations that can be obtainable to be gained for client subsequent request for similar content. It lowers congestion of the internet and optimizes congestion of a network. CUC-Cisco Unity Connection: it is a heterogeneous desktop or web based application interface employed accordingly with other communication technologies. CUCM: Cisco Unified Communication Manager: it is a platform for call control of unified communications that gives services for instance web conferencing, messaging, video, voice, and session management in VOIP network. CUE-Cisco Unity Express: it gives ISR (Integrated Services Routers) audio, fax, and messaging voice application to a VOIP telephones DID-Direct Inward Dial: it is a service provided by telephone companies that permit clients to access the details of VOIP without mechanized customer care DN-Direct Number: it is a directory’s direct number that is allocated to phones and retains its consistency across entire calls EM-Element Managers: offers standard management of element capabilities for instance security, performance, accounting, configuration and fault, enhances chassis IP configuration details, gives the ability for Cisco IOS software new version download FAC- Forced Authorization Codes: permits one to regulate the forms of VOIP calls that can be placed by certain users, forcing the user to input a valid code of authorization on the phone before completion of the call Locales (Cisco Phone): it gives voice prompt and translated text for user web pages, user applications and phone display in the user chosen locales. MVA-Mobile Voice Access: mobile phones are employed by clients to control their calls by use of one phone number and capture them in calls progress on their phones’ desktop SOAP-Simple Object Access Protocol: information exchanger protocol in a decentralized surrounding, defines an entire framework for expressing message content, the preferred recipient and if it is mandatory or optional. RTMT-Real Time Monitoring Tool: it is an application of client side that employs TCP and HTTP to monitor performance of a network. Creates network alerts and transfer them to relevant emails. Annexes Examples of Configuration Setting Traffic’s Highest Priority The configuration example below is used to set the highest traffic priority from TCP port 1494. It involves four steps, with each step following the configuration as shown below.  VOIP traffic requires to be assigned EF DSCP value: !--- Classifying all traffic coming with dscp value of EF under this class-map. Switch(config)# class-map match-all AutoQoS-VoIP-RTP-Trust Switch(config-cmap)# match ip dscp ef Switch(config)# policy-map AutoQoS-Police-CiscoPhone Switch(config-pmap)# class AutoQoS-VoIP-RTP-Trust !--- Again setting the dscp value back to EF. Switch(config-pmap-c)# set dscp ef Switch(config-pmap-c)# police 320000 8000 exceed-action policed-dscp-transmit  Traffic starting at TCP 1494 requires to be assigned a CS4 DSCP value: Switch(config)# access-list 100 permit tcp eq 1494 Switch(config)# class-map tcp Switch(config-cmap)# match access-group 100 Switch(config)# policy-map AutoQoS-Police-CiscoPhone Switch(config-pmap)# class tcp Switch(config-pmap-c)# set dscp cs4  All other traffic requires to be allocated CS3: Switch(config)# access-list 200 permit ip any any Switch(config)# class-map default Switch(config-cmap)# match access-group 200 Switch(config)# policy-map AutoQoS-Police-CiscoPhone Switch(config-pmap)# class default Switch(config-pmap-c)# set dscp cs3  It should be applied under relevant interfaces: Switch(config)# interface Switch(config-if)# service-policy References Cisco. (2001). Quality of service for voice of IP. Retrieved October 21, 2012, from www.cisco.com/en/US/docs/ios/solutions_docs/qos_solutions/QoSVoIP/QoSVoIP.html Cisco. (2005). Cisco AutoQoS Q&A. Retrieved October 21, 2012, from http://www.cisco.com/en/US/technologies/tk543/tk879/technologies_qas0900aecd8020a589.html Cisco (2006a) IP application services using Cisco service assurance agent and internetwork performance monitor to manage quality of service in voice over IP networks. Retrieved October 21, 2012, from http://www.cisco.com/en/US/tech/tk648/tk362/technologies_tech_note09186a0080094b26.shtml Cisco. (2006b). Voice quality voip over frame relay with quality of service (fragmentation, traffic shaping, LLQ / IP RTP priority). Retrieved October 21, 2012, from http://www.cisco.com/en/US/tech/tk652/tk698/technologies_configuration_example09186a0080094af9.shtml Cisco. (2007a). ATM traffic management configuring atm per-vc queuing on the MC3810. Retrieved October 21, 2012 from http://www.cisco.com/en/US/tech/tk39/tk51/technologies_configuration_example09186a0080094b39.shtml Cisco. (2007b). Cisco catalyst 3750 series switches. Cisco catalyst 3750 QoS configuration examples. Retrieved 21 October 21, 2012, from http://www.cisco.com/en/US/products/hw/switches/ps5023/products_tech_note09186a0080883f9e.shtml Cisco. (2008). Cisco quality of service. White Paper. Retrieved October 21, 2012, from www.cisco.com/en/US/technologies/tk389/tk813/technologies_white_paper0900aecd802b68b1.pdf Cisco. (2009). QoS Frequently Asked Questions. Retrieved October 21, 2012, from http://www.cisco.com/en/US/tech/tk543/tk545/technologies_q_and_a_item09186a00800cdfab.shtml Cisco. (2012). Internetworking technology handbook. Retrieved October 21, 2012, from http://docwiki.cisco.com/wiki/Internetworking_Technology_Handbook Cisco. (n.d. a). Quality of service networking. Retrieved October 21, 2012, from users.freenet.am/~file/DownDB/CISCO_PDF/QualityOfService_CISCO.pdf Cisco. (n.d.b). Isco ios quality of service solutions configuration guide, release 12.2 Retrieved October 21, 2012, from http://www.cisco.com/en/US/docs/ios/12_2/qos/configuration/guide/qcfintro.html Cisco. (n.d.c). AutoQoS catalyst 6500 release 12.2SX software configuration guide. Retrieved October 21, 2012, from http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.2SX/configuration/guide/auo_qos.html Netgear. (2009). Quality of service (QoS) on Netgear switches. Retrieved October 21, 2012, from kb.netgear.com/app/answers/detail/a_id/12880. Read More