![Basic QoS Configuration (cont’d)
Step 1: create class-maps to categorize traffic types.
IOS Commands:
Router(config)#class-map [match-any | match-all] class-
name
After you are in class-map configuration mode, you can
specify multiple match statements to match traffic, and all
traffic that meets the criteria that you specified with the
match commands is categorized under the class-map.
After the class-maps are defined, the first step of MQC is
complete.
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![IOS Commands Review
class-map Creates a class map to be used for matching packets to the class whose
name you specify.
match protocol Defines the match criteria to classify traffic. NBAR (Network-Based
Application Recognition) will be invoked.
class Specifies the name of the class whose policy you want to create or change or
to specify the default class (commonly known as the class-default class) before
you configure its policy.
policy-map Enters policy-map configuration mode and creates or modifies a policy
map that can be attached to one or more interfaces to specify a service policy.
bandwidth The bandwidth command (used in policy-map) provides a minimum
bandwidth guarantee during congestion.
priority The priority command (used in policy-map) implements a maximum
bandwidth guarantee.
To confirm the QOS is working you would use the command: show policy-map
interface [fastethernet 0/0]
To show class map(s) defined: show class-map
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Week11 qo s-2017(1)
- 1. Lecture 11 – Quality of Service Li DCN330 Fall 2017
- 2. QoS Why Do We Need QoS? QoS Architecture Models QoS Architecture Components Basic Configurations Example in Queuing IOS Commands Review 2 DCN330 Fall 2017
- 3. 3 Why Do We Need QoS? Video Streaming Services Video Conferencing VoIP QoS development inspired by new types of applications in IP environment: DCN330 Fall 2017
- 4. Why Do We Need QoS? Multiple application networks are being combined into consolidated corporate utility networks Traffic can suffer from the following symptoms: Delay (or latency)- is the time that is required for a packet to travel from its source to its destination. Jitter (or delay variation)- is the uneven arrival of packets. Packet drops (or packet loss)-Packet drops occur when a link is congested and a buffer overflows. 4 DCN330 Fall 2017
- 5. Why Do We Need QoS? Voice No more than 150 ms of one-way delay No more than 30 ms of jitter No more than 1 percent packet loss Video No more than 150ms of one-way delay for interactive voice applications (e.g. video conferending) No more than 30 ms of jitter No more than 1 percent packet loss Data Applications have varying delay and loss characteristics 5 DCN330 Fall 2017
- 6. QoS Why Do We Need QoS? QoS Architecture Models QoS Architecture Components Basic Configurations Example in Queuing IOS Commands Review 6 DCN330 Fall 2017
- 7. 7 QoS Architecture Models Best Effort Service Integrated Service Differentiated Service DCN330 Fall 2017
- 8. 8 QoS Architecture Models Best Effort Service: All packets treated equally Unpredictable bandwidth Unpredictable delay and jitter DCN330 Fall 2017
- 9. 9 QoS Architecture Models Integrated Service (IntServ) IntServ is often referred to as “Hard QoS,” because it can make strict bandwidth reservations. IntServ uses signaling among network devices to provide bandwidth reservations. Resource Reservation Protocol (RSVP) is an example of an IntServ approach to QoS. Because IntServ must be configured on every router along a packet’s path, the main drawback of IntServ is its lack of scalability. DCN330 Fall 2017
- 10. 10 QoS Architecture Models Differentiated Service (DiffServ) DiffServ, as the name suggests, differentiates between multiple traffic flows. Specifically, packets are “marked,” and routers and switches can then make decisions (for example, dropping or forwarding decisions) based on those markings. Each compliant node can have various behaviors DiffServ is far more flexible and scalable DiffServ can be pervasively deployed throughout the network Focus of today’s lecture DCN330 Fall 2017
- 11. QoS Why Do We Need QoS? QoS Architecture Models QoS Architecture Components Basic Configurations Example in Queuing IOS Commands Review 11 DCN330 Fall 2017
- 12. 12 QoS Architecture Components Classification and Marking Traffic Shaping/Policing Congestion Management Congestion Avoidance Link Efficiency DCN330 Fall 2017
- 13. Classification and Marking Options QoS Tools (You must have a QoS tool that references those marking and alters the packets’ treatment based on those markings, because marking alone does not alter the behaviour of packets. ) Classification—Classification is the process of placing traffic into different categories. Multiple characteristics can be used for classification. For example, POP3, IMAP, SMTP, and Exchange traffic could all be placed in an “EMAIL” class. Classification does not, however, alter bits in the frame or packet. Marking—Marking alters bits (for example, bits in the ToS byte) within a frame, cell, or packet to indicate how the network should treat that traffic. Marking alone does not change how the network treats a packet. Other tools (for example, queuing tools) can, however, reference those markings and make decisions based on them. 13 DCN330 Fall 2017
- 14. 14 Classification and Marking Options Classification can be done on: Layer 1 criteria: such as ingress physical interface Layer 2 criteria: such as IEEE 802.1Q/p CoS (Class of Service) Layer 3 criteria: such as IP DSCP Layer 4 criteria: such as TCP/UDP port(s) Layer 7 criteria: such as Packet Content (NBAR) i.e. HTTP, HTTPS, FTP etc. Marking can be done on: Layer 2 fields: such as IEEE 802.1Q/p CoS Layer “2.5” fields: such as MPLS EXP Layer 3 fields: such as IP DSCP DCN330 Fall 2017
- 15. Classification & Marking Tools DiffServ at Layer 3 Inside an IPv4 header is a byte called the type of service (ToS) byte. You can mark packets, using bits within the ToS byte, with either IP Precedence or Differentiated Service Code Point (DSCP) markings. The challenge with so many values at your disposal is that the value you choose to represent a certain level of priority can be treated differently by a router or switch under someone else’s administration. 15 DCN330 Fall 2017
- 16. Classification & Marking Tools DiffServ at Layer 3 The 6 leftmost bits (or DSCP) in the ToS yields 64 possible values These 64 values called per-hop behaviours (PHBs). because they indicate how packets should be treated by each router hop along the path from the source to the destination 16 DCN330 Fall 2017
- 17. 17 QoS Architecture Components Classification and Marking Traffic Shaping/Policing Congestion Management Congestion Avoidance Link Efficiency DCN330 Fall 2017
- 18. QoS Architecture Components (cont’d) Policing and shaping—Sometimes, instead of making a minimum amount of bandwidth available for specific traffic types, you might want to limit the available bandwidth. Both policing and shaping tools can accomplish this objective. Collectively, these tools are called traffic conditioners. Congestion management—When you hear the term congestion management, think queuing. These concepts are the same. When an interface’s output software queue contains packets, the interface’s queuing strategy determines how the packets are emptied from the queue. We will present details later in the lecture. Congestion avoidance—If an interface’s output queue fills to capacity, newly arriving packets are discarded (that is, “tail-dropped”), regardless of the priority that is assigned to the discarded packet. Link efficiency—To make the most of the limited bandwidth that is available on slower-speed links, you can choose to implement compression or Link Fragmentation and Interleaving (LFI). 18 DCN330 Fall 2017
- 19. QoS Why Do We Need QoS? QoS Architecture Models QoS Architecture Components Basic Configurations Example in Queuing IOS Commands Review 19 DCN330 Fall 2017
- 20. Basic QoS Configuration One of the most powerful approaches to QoS configuration is the Modular Quality of Service Command-Line Interface (MQC). 20 DCN330 Fall 2017
- 21. Basic QoS Configuration (cont’d) Step 1: create class-maps to categorize traffic types. IOS Commands: Router(config)#class-map [match-any | match-all] class- name After you are in class-map configuration mode, you can specify multiple match statements to match traffic, and all traffic that meets the criteria that you specified with the match commands is categorized under the class-map. After the class-maps are defined, the first step of MQC is complete. 21 DCN330 Fall 2017
- 22. Basic QoS Configuration (cont’d) Step 2: create a policy-map, which assigns characteristics (for example, marking) to the classified traffic. To enter policy-map configuration mode, issue the following command: Router(config)#policy-map policy-name From policy-map configuration mode, enter policy-map- class configuration mode with the following command: Router(config-pmap)#class class-name 22 DCN330 Fall 2017
- 23. Basic QoS Configuration (cont’d) Step 3: apply the policy-map to an interface. Command: Router(config-if)#service-policy {input | output} policy- map-name 23 DCN330 Fall 2017
- 24. Basic QoS Configuration (cont’d) Example: you are classifying various types of e-mail traffic (for example, SMTP, IMAP, and POP3) into one class-map. The KaZaa protocol, which is used for music downloads, is placed in another class-map. Voice over IP (VoIP) traffic is placed in yet another class-map. Then, the policy-map assigns bandwidth allocations or limitations to these traffic types. •Explanation: the QOS-STUDY policy-map makes 128 kbps of bandwidth available to e-mail traffic. However, KaZaa version 2 traffic bandwidth is limited to 32 kbps (that is, KaZaa traffic higher than this rate will be dropped). Voice packets not only have access to 256 kbps of bandwidth, but they also receive “priority” treatment, meaning that they are sent first (that is, ahead of other traffic) up to the 256-kbps limit. 24 Note: Some application protocols may not be available by default on your router, which needs to be supported by the PDLM (or application recognition modules) installation. DCN330 Fall 2017
- 25. QoS Why Do We Need QoS? QoS Architecture Models QoS Architecture Components Basic Configurations Example in Queuing IOS Commands Review 25 DCN330 Fall 2017
- 26. Queuing Queuing is sometimes referred to as congestion management, queuing mechanisms identify how traffic from multiple streams is sent out of an interface that is currently experiencing congestion. We will examines approaches to queuing and emphasizes the queuing approaches configured via MQC. Queuing Basics When a device, such as a switch or a router, is receiving traffic faster than it can be transmitted, the device attempts to buffer the extra traffic until bandwidth is available. This buffering process is called queuing. You can use queuing mechanisms to influence in what order various traffic types are emptied from the queue. 26 DCN330 Fall 2017
- 27. Queuing (cont’d) Two queuing mechanisms: CB-WFQ (Class-Based Weighted Fair Queueing) and LLQ (Low Latency Queuing). The WFQ mechanism made sure that no traffic was starved out. However, WFQ did not make a specific amount of bandwidth available for defined traffic types. You can, however, specify a minimum amount of bandwidth to make available for various traffic types using the CB-WFQ mechanism. CB-WFQ is configured through the three-step MQC process. Using MQC, you can create up to 63 class-maps and assign a minimum amount of bandwidth for each one. Note that the reason you cannot create 64 class-maps is that the class-default class-map has already been created. Low Latency Queuing (LLQ) is almost identical to CB-WFQ. However, with LLQ, you can instruct one or more class-maps to direct traffic into a priority queue. 27 DCN330 Fall 2017
- 28. Queuing (cont’d) CB-WFQ: You can make a specific amount of bandwidth available for classified traffic. To allocate a bandwidth amount, use the following command, noting that the units of measure are in kbps: Router(config-pmap-c)#bandwidth {kbps} Instead of specifying an exact amount of bandwidth, you can specify a percentage of the interface bandwidth. For example, a policy-map could allocate 25 percent of an interface’s bandwidth. Then, that policy-map could be applied to, for example, a Fast Ethernet interface and also to a slower-speed serial interface. Router(config-pmap-c)#bandwidth percent {value} 28 DCN330 Fall 2017
- 29. Queuing (cont’d) LLQ: You can use either of the following commands to direct packets to the priority queue: Router(config-pmap-c)#priority bandwidth (Note that the bandwidth units of measure are in kbps.) Router(config-pmap-c)#priority percent percent (Note that the percent option references a percentage of the interface bandwidth.) 29 DCN330 Fall 2017
- 30. Queuing (cont’d) LLQ Example: in the example on the right, NBAR is being used to recognize http traffic, and that traffic is placed in the SURFING class. Note that NBAR (Network-Based Application Recognition) is invoked with the following command: Router(config-cmap)# match protocol Voice packets are placed in the VOICE class. The QOS_STUDY policy-map gives 128 kbps of bandwidth to the http traffic while giving 256 kbps of priority bandwidth to voice traffic. Then the policy-map is applied outbound to interface serial 0/1. 30 DCN330 Fall 2017
- 31. QoS Why Do We Need QoS? QoS Architecture Models QoS Architecture Components Basic Configurations Example in Queuing IOS Commands Review 31 DCN330 Fall 2017
- 32. IOS Commands Review class-map Creates a class map to be used for matching packets to the class whose name you specify. match protocol Defines the match criteria to classify traffic. NBAR (Network-Based Application Recognition) will be invoked. class Specifies the name of the class whose policy you want to create or change or to specify the default class (commonly known as the class-default class) before you configure its policy. policy-map Enters policy-map configuration mode and creates or modifies a policy map that can be attached to one or more interfaces to specify a service policy. bandwidth The bandwidth command (used in policy-map) provides a minimum bandwidth guarantee during congestion. priority The priority command (used in policy-map) implements a maximum bandwidth guarantee. To confirm the QOS is working you would use the command: show policy-map interface [fastethernet 0/0] To show class map(s) defined: show class-map 32 DCN330 Fall 2017
- 33. IOS Commands Review (cont’d) Difference between bandwidth and priority command. http://www.cisco.com/c/en/us/support/docs/quality-of-service-qos/qos-packet-marking/10100-priorityvsbw.html 33 DCN330 Fall 2017
- 34. IOS Commands Review (cont’d) Although the bandwidth guarantees provided by the bandwidth and priority commands have been described with words like "reserved" and "bandwidth to be set aside", neither command implements a true reservation. In other words, if a traffic class is not using its configured bandwidth, any unused bandwidth is shared among the other classes. The queueing system imposes an important exception to this rule with a priority class. http://www.cisco.com/c/en/us/support/docs/quality-of-service-qos/qos-packet-marking/10100-priorityvsbw.html 34 DCN330 Fall 2017
- 35. In-Class Activity Finish the following task in groups: In a WAN connection between R1 and R2, you want to make sure the outbound HTTP traffic on the interface S0/0/0 of R1, can be guaranteed with the 1Mbps bandwidth. Try to apply a QoS policy following the steps: Step 1: Create a class-map “WEB” to category this HTTP traffic. Step 2: Create a policy-map “MY- QOS-POLICY”, which assigns characteristics (for example, marking) to the classified traffic. Step 3: Apply the policy-map to an interface. Step 4: Verify your class-map and policy-map 35 Note: The router type can be Cisco 2811 with one WIC-2T module installed (two serial ports are available on this module). DCN330 Fall 2017
- 36. References Cisco IP Telephony Flash Cards: Weighted Random Early Detection (WRED). Available at http://www.ciscopress.com/articles/article.asp?p=352991 Comparing the bandwidth and priority Commands of a QoS Service Policy. Available at: http://www.cisco.com/c/en/us/support/docs/quality-of-service- qos/qos-packet-marking/10100-priorityvsbw.html Comparing Traffic Policing and Traffic Shaping for Bandwidth Limiting. Available at: http://www.cisco.com/c/en/us/support/docs/quality-of-service-qos/qos- policing/19645-policevsshape.html 36 DCN330 Fall 2017