IP quality of service

IP Quality of Service Objectives  Upon completing this module, you will be able to:     Describe the need for IP QoS Describe the Integrated Services model Describe the Differentiated Services model Describe the building blocks of IP QoS mechanisms (classification, marking, metering, policing, shaping, dropping, forwarding, queuing) Inner Mongolia University Introduction Objectives  Upon completing this lesson, you will be able to:  Describe different types of applications and services that have special resource requirements  List the network components that affect the throughput, delay, and jitter in IP networks  List the benefits of deploying QoS mechanisms in IP networks  Describe typical enterprise and service provider networks and their QoS-related requirements Inner Mongolia University Why IP QoS?      Application X is slow Video broadcast occasionally stalls Phone calls over IP are no better than over satellite Phone calls can have very bad voice quality ATMs (the money-dispensing type) are nonresponsive Inner Mongolia University Because  Application X is slow! (not enough bandwidth)  Video broadcast occasionally stalls! (delay temporarily increases – jitter)  Phone calls over IP are no better than over satellite! (too much delay)  Phone calls can have very bad voice quality! (too many phone calls – admission control)  ATMs (the money-dispensing type) are nonresponsive! (too many drops) Inner Mongolia University What Causes  Lack of bandwidth?: Multiple flows are contesting for a limited amount of bandwidth  Too much delay?: Packets have to traverse many network devices and links  Variable delay?: Sometimes there is a lot of other traffic, which results in more delay  Drops?: Packets have to be dropped when a link is congested Inner Mongolia University Available Bandwidth IP IP IP IP 512 kbps 256 kbps 10 Mbps 100 Mbps BWmax = min(10M, 256k, 512k, 100M)=256 kbps BWavail = BWmax /Flows   Maximum available bandwidth equals the bandwidth of the weakest link Multiple flows are competing for the same bandwidth, resulting in much less bandwidth being available to one single application Inner Mongolia University End-to-End Delay IP IP Propagation Delay (P1) Processing and Queuing Delay (Q1) IP Propagation Delay (P2) Processing and Queuing Delay (Q2) IP Propagation Delay (P3) Propagation Delay (P4) Processing and Queuing Delay (Q3) Delay = P1 + Q1 + P2 + Q2 + P3 + Q3 + P4 = X ms  End-to-end delay equals a sum of all propagation, processing, and queuing delays in the path  Propagation delay is fixed; processing and queuing delays are unpredictable in best-effort networks Inner Mongolia University Processing, Queuing, and Propagation Delay IP IP Processing Delay IP Bandwidth Forwarding IP Queuing Delay Propagation Delay  Processing delay is the time it takes for a router to take the packet from an input interface and put it into the output queue of the output interface  Queuing delay is the time a packet resides in the output queue of a router  Propagation or serialization delay is the time it takes to transmit a packet 10 Inner Mongolia University Case Study Implementation #1  Core to Distribution: • Custom queuing  Distribution to Branch: • Priority queuing or • Custom queuing with a priority queue  Options: • Traffic shaping • Adaptation to Frame Relay congestion notification 77 Inner Mongolia University Case Study Implementation #2  Core to Distribution: • Class-based weighted fair queuing (CBWFQ) • Class-based low-latency queuing (CBLLQ)  Distribution to Branch: • Class-based weighted fair queuing (CBWFQ) • Class-based low-latency queuing (CBLLQ)  Options: • • • • Class-based shaping Adaptation to Frame Relay congestion notification Class-based policing Weighted random early detection (WRED) 78 Inner Mongolia University Summary  Upon completing this lesson, you should be able to:  Describe the typical structure of an enterprise network  Describe the need for QoS in enterprise networks  List typical QoS requirements in enterprise networks  List the QoS mechanisms that are typically used in enterprise networks Inner Mongolia University Review Questions 1.What is the typical enterprise network topology? 2.How is resilience achieved? 3.Based on what information typical enterprise networks apply QoS? Inner Mongolia University Services Provider Case Study Objectives  Upon completing this lesson, you will be able to:  Describe the typical structure of a service provider network  Describe the need for QoS in service provider networks  List typical QoS requirements in service provider networks  List the QoS mechanisms that can be used in service provider networks Inner Mongolia University Typical Service Provider Networks Core ATM, SONET/SDH, DPT, GE, Partial mesh Rings ATM, SONET/SDH, DPT, GE, Redundant connections Rings Distribution (regional POPs) Frame Relay, ATM, leased line (analog, TDM), dial-up (PSTN, ISDN, GSM), xDSL, (fast) Ethernet, Single connections Optional redundant connections Dial backup Access (customers)     Typical service provider networks use a high-speed partially meshed core (backbone) Regional POPs use two or more connections to the core There may be another layer of smaller POPs connected to distribution-layer POPs Customers are usually connected to the service provider via a single point-to-point link (a secondary link or a dial line can be used to improve resilience) 83 Inner Mongolia University QoS in Service Provider Networks  Service providers extend their service offerings by introducing quality  Customers can get bandwidth guarantees (like CIR in Frame Relay)  Customers can get delay guarantees (like CBR in ATM)  Customers can get preferential treatment in case of congestion (Olympic service)  QoS mechanisms have to be deployed where congestion is likely (usually at the network edge)  The customer traffic is identified based on source or destination IP addresses 84 Inner Mongolia University Case Study  A service provider wants to offer bronze, silver, gold and premium services:     Bronze gets 10% of available bandwidth Silver gets 20% of available bandwidth Gold gets 30% of available bandwidth Premium gets 40% of available bandwidth with a lowdelay guarantee 85 Inner Mongolia University Case Study Implementation  Class-based weighted fair queuing (CBWFQ) on slow to moderate-speed links  Class-based low latency queuing (CBLLQ) on slow to moderate-speed links  Weighted random early detection (WRED) on fast links 86 Inner Mongolia University Summary  Upon completing this lesson, you should be able to:  Describe the typical structure of a service provider network  Describe the need for QoS in service provider networks  List typical QoS requirements in service provider networks  List the QoS mechanisms that can be used in service provider networks Inner Mongolia University Review Questions 1.What is the typical topology of service provider networks? 2.How is resilience achieved? 3.Based on what information typical service provider networks apply QoS? Inner Mongolia University Module Summary  Upon completing this module, you should be able to: Describe the need for IP QoS Describe the Integrated Services model Describe the Differentiated Services model Describe the building blocks of IP QoS mechanisms (classification, marking, metering, policing, shaping, dropping, forwarding, queuing)  List the IP QoS mechanisms available in Cisco IOS  Describe what QoS features are supported by different IP QoS mechanisms     Inner Mongolia University Thank You and Good-bye !! Cisco’s Certification Track 91 Inner Mongolia University ... Forwarding IP IP IP IP IP Tail-drop  Tail-drops occur when the output queue is full These are the most common drops which happen when a link is congested  There are also many other types of drops... there is a lot of other traffic, which results in more delay  Drops?: Packets have to be dropped when a link is congested Inner Mongolia University Available Bandwidth IP IP IP IP 512 kbps 256... able to:     Describe the need for IP QoS Describe the Integrated Services model Describe the Differentiated Services model Describe the building blocks of IP QoS mechanisms (classification,