© 2001, Cisco Systems, Inc. Traffic Shaping and Policing

© 2001, Cisco Systems, Inc. QOS v1.0—4-2 Objectives Upon completing this module, you will be able to: Describe and configure generic traffic shaping (GTS) Describe and configure Frame Relay traffic shaping (FRTS) Describe and configure committed access rate (CAR) Name other mechanisms that support traffic shaping and policing (class-based policing and class-based shaping)

Traffic Shaping and Policing © 2001, Cisco Systems, Inc. QOS v1.0—4-3

© 2001, Cisco Systems, Inc. QOS v1.0—4-4 Objectives Upon completing this lesson, you will be able to: Describe the need for implementing traffic policing and shaping mechanisms List traffic policing and shaping mechanisms available in Cisco IOS Describe the benefits and drawbacks of traffic shaping and policing mechanisms

© 2001, Cisco Systems, Inc. QOS v1.0—4-5 Traffic Shaping and Policing Traffic shaping and policing mechanisms are used to rate-limit traffic classes. They have to be able to classify packets and meter their rate of arrival. Traffic shaping delays excess packets so that they stay within the rate limit. Traffic policing typically drops excess traffic so that it stays within the limit; alternatively, it can remark excess traffic. ClassifierMarker Dropper Meter Traffic Stream

© 2001, Cisco Systems, Inc. QOS v1.0—4-6 Why Use Rate Limiting? To handle congestion at ingress to ATM/Frame Relay network with asymmetric link bandwidths To limit access to resources when high-speed access is used but not desired To limit certain applications or classes To implement a virtual TDM system

© 2001, Cisco Systems, Inc. QOS v1.0—4-7 Typical Traffic Shaping or Policing Applications Low-Speed Link High-Speed Link Output interface is not congested; queuing and WRED do not work. Output interface is not congested; queuing and WRED do not work. Congestion in WAN network results in nonintelligent Layer 2 drops. Server Farm WAN Internet FastEthernet 256 kbps 64 kbps 128 kbps Access to resources is limited. A virtual TDM or leased line is implemented over a single physical link on one side

© 2001, Cisco Systems, Inc. QOS v1.0—4-8 Shaping vs. Policing Benefits of shaping: –Shaping does not drop packets. –Shaping supports interaction with Frame Relay congestion indication. Benefits of policing: –Policing supports marking. – Buffer usage is not increased (shaping requires an additional queuing system).

© 2001, Cisco Systems, Inc. QOS v1.0—4-9 How Do Routers Measure Traffic Rate? Routers use the token bucket mathematical model to keep track of packet arrival rate. The token bucket model is used whenever a new packet is processed. The return value is conform or exceed. Bandwidth Time Link Bandwidth Rate Limit Exceeding Traffic Conforming Traffic

© 2001, Cisco Systems, Inc. QOS v1.0— Token Bucket 500 bytes Conform Action

© 2001, Cisco Systems, Inc. QOS v1.0— Token Bucket (cont.) 300 bytes Exceed Action 300 bytes

© 2001, Cisco Systems, Inc. QOS v1.0—4-12 Token Bucket B c is normal burst size (specifies sustained rate) B e is excess burst size (specifies length of burst) B c + B e B c of tokens is added every T c [ms] T c = B c / CIR Time Link Utilization TcTc 2*T c 3*T c 4*T c 5*T c BcBc BcBc BcBc BcBc BcBc BcBc Link BW Average BW (CIR) BeBe

© 2001, Cisco Systems, Inc. QOS v1.0—4-13 Traffic Shaping and Policing Mechanisms Shaping mechanisms: –Generic traffic shaping (GTS) –Frame Relay traffic shaping (FRTS) –Class-based shaping Policing mechanisms: –Committed access rate (CAR) –Class-based policing

© 2001, Cisco Systems, Inc. QOS v1.0—4-14 Summary Upon completing this lesson, you should be able to: Describe the need for implementing traffic policing and shaping mechanisms List traffic policing and shaping mechanisms available in Cisco IOS Describe the benefits and drawbacks of traffic shaping and policing mechanisms

© 2001, Cisco Systems, Inc. QOS v1.0—4-15 Lesson Review 1.How do shaping and policing mechanisms keep track of the traffic rate? 2.Which shaping mechanisms are available with Cisco IOS software? 3.Which policing mechanisms are available with Cisco IOS software? 4.What are the main differences between shaping and policing?

Generic Traffic Shaping © 2001, Cisco Systems, Inc. QOS v1.0—4-16

© 2001, Cisco Systems, Inc. QOS v1.0—4-17 Objectives Upon completing this lesson, you will be able to: Describe the GTS mechanism Describe the benefits and drawbacks of GTS Configure GTS on Cisco routers Monitor and troubleshoot GTS

© 2001, Cisco Systems, Inc. QOS v1.0—4-18 Generic Traffic Shaping Can shape multiple classes (classification) Can measure traffic rate of individual classes (metering) Delays packets of exceeding classes (shaping) Traffic Stream ClassifierMarker Shaper Dropper Meter

© 2001, Cisco Systems, Inc. QOS v1.0—4-19 GTS Building Blocks Classifier No Physical Interface Queue(s) Shaping WFQ Yes Shaping WFQ Shaping WFQ No Yes Forwarder

© 2001, Cisco Systems, Inc. QOS v1.0—4-20 GTS Overview GTS is multiprotocol. GTS uses WFQ for the shaping queue. GTS can be implemented in combination with any queuing mechanisms: –FIFO queuing –Priority queuing (PQ) –Custom queuing (CQ) –Weighted fair queuing (WFQ) GTS works on output only.

© 2001, Cisco Systems, Inc. QOS v1.0—4-21 GTS Implementation The software queue may have no function if the sum of all shaping rates is less than the link bandwidth. Shaping Queue (WFQ) Shaping Queue (WFQ) Software Queue (FIFO, PQ, CQ, WFQ,...) Software Queue (FIFO, PQ, CQ, WFQ,...) Hardware Queue (FIFO) Hardware Queue (FIFO) Dispatches packets at configured rate Dispatches packets at line rate Bypasses the software queue if it is empty and there is room in the hardware queue

© 2001, Cisco Systems, Inc. QOS v1.0—4-22 Configuring GTS Enables traffic shaping of all outbound (sub)interface traffic In IOS versions prior to 11.2(19) and 12.0(4), optimum switching is disabled on all interfaces if traffic shaping is enabled on any interface traffic-shape rate bit-rate [burst-size [excess- burst-size]] Router(config-if)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-23 Configuring GTS (cont.) Bit rate: average traffic rate in bps (equivalent to Frame Relay CIR) Burst size: amount of traffic sent in a measurement interval in bits (equivalent to Frame Relay B c ) Default value: 1/8 of bit rate traffic-shape rate bit-rate [burst-size [excess- burst-size]] Router(config-if)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-24 Configuring GTS (cont.) Excess burst size: amount of excess traffic that can be sent during the first burst in bps (equivalent to Frame Relay B e ) –Default value: no excess burst Measurement interval (T c ): computed from bit rate and burst size –T c smaller than 25 ms is rejected: T c greater than 125 ms is reduced traffic-shape rate bit-rate [burst-size [excess- burst-size]] Router(config-if)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-25 Configuring GTS (cont.) Traffic-shape group shapes outbound traffic matched by the specified access list. Several traffic-shape group commands can be configured on the same interface. The traffic-shape rate and traffic-shape group commands cannot be mixed on the same interface. A separate token bucket and shaping queue is maintained for each traffic-shape group command. Traffic not matching any access list is not shaped. traffic-shape group access-list bit-rate [burst [excess-burst]] Router(config-if)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-26 GTS Example #1 An ISP wants to sell a service in which a customer may use all of an E1 line for 30 seconds in a burst, but on a long-term average is limited to 256 kbps. GTS parameters: –Bit rate: 256,000—output rate is 256,000 bps –Burst size—32,000 the number of bits sent in 125 ms –Excess burst size: 61,440,000 = 2,048,000 x 30

© 2001, Cisco Systems, Inc. QOS v1.0—4-27 Core Customer GTS Example #1 (cont.) interface ethernet0/0 traffic-shape rate ! interface serial1/0 traffic-shape rate interface ethernet0/0 traffic-shape rate ! interface serial1/0 traffic-shape rate Because the ISP wants to control the total amount of load, the configuration would be done on both the inbound and outbound interfaces. WAN

© 2001, Cisco Systems, Inc. QOS v1.0—4-28 Core Customer GTS Example #2 The customer wants to be sure that web traffic will never use more than 64 kbps. WAN interface ethernet 0/0 traffic-shape group interface serial 1/0 traffic-shape group ! access-list 101 permit tcp any any eq www interface ethernet 0/0 traffic-shape group interface serial 1/0 traffic-shape group ! access-list 101 permit tcp any any eq www

© 2001, Cisco Systems, Inc. QOS v1.0—4-29 Monitoring GTS Router#show traffic-shape access Target Byte Sustain Excess Interval Increment Adapt I/F list Rate Limit bits/int bits/int (ms) (bytes) Active Se3/ Router#show traffic-shape access Target Byte Sustain Excess Interval Increment Adapt I/F list Rate Limit bits/int bits/int (ms) (bytes) Active Se3/ CIR BcBc BeBe T c =B c /CIR MAX = (Bc + B e )/8B c = T c * CIR Do we listen to FECN/BECN? Displays current traffic shaping configuration show traffic-shape Router(config)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-30 Monitoring GTS (cont.) Router#show traffic-shape statistics Access Queue Packets Bytes Packets Bytes Shaping I/F List Depth Delayed Delayed Active Se3/ yes Router#show traffic-shape statistics Access Queue Packets Bytes Packets Bytes Shaping I/F List Depth Delayed Delayed Active Se3/ yes Depth of the associated WFQ queue for delayed packets Number of packets/bytes sent on the interface Subset of the previous number of packets/bytes delayed via the WFQ queue Displays traffic shaping statistics show traffic-shape statistics Router(config)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-31 Monitoring GTS (cont.) router#show traffic-shape queue Traffic queued in shaping queue on Serial0 (depth/weight) 1/4096 Conversation 254, linktype: ip, length: 232 source: , destination: , id: 0x0001, ttl: 208, TOS: 0 prot: 17, source port 11111, destination port router#show traffic-shape queue Traffic queued in shaping queue on Serial0 (depth/weight) 1/4096 Conversation 254, linktype: ip, length: 232 source: , destination: , id: 0x0001, ttl: 208, TOS: 0 prot: 17, source port 11111, destination port Displays the shaping queue contents show traffic-shape queue Router(config)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-32 GTS on Frame Relay Interfaces GTS can be implemented on any type of (sub)interface. GTS supports additional features when implemented on Frame Relay interfaces: –Adaptation to Frame Relay congestion notification –BECN-to-FECN reflection –FECN creation on congestion

© 2001, Cisco Systems, Inc. QOS v1.0—4-33 Frame Relay Refresher Frame Relay explicit congestion notification –FECN (Forward explicit congestion notification) –BECN (Backward explicit congestion notification) –CLLM (Consolidated link layer management) Implicit congestion notification –Network discards detected by end user at higher layers –DE (discard eligibile) bit

© 2001, Cisco Systems, Inc. QOS v1.0—4-34 Frame 1 Frame 1 FECN Frame 2 Frame 2 BECN Congestion This SideNo Congestion This Side Switch monitors all transmit queues for congestion. SenderSender ReceiverReceiver Frame Relay Switch Frame Relay Switch Frame Relay FECN/BECN Congestion Control Sa m e Virtual Circuit (VC) Frame Relay switch detects congestion on output queue and informs: –The receiver, by setting the FECN bit on forwarded frames –The source, by setting the BECN bit on frames going in the opposite direction

© 2001, Cisco Systems, Inc. QOS v1.0—4-35 GTS Frame Relay Congestion Adaptability On a Frame Relay (sub)interface, GTS can adapt dynamically to available Frame Relay bandwidth by integrating BECN signals: –The GTS bit rate is reduced when BECN packets are received in order to reduce the data flow through the congested Frame Relay network. –Adaptation is done on a per- (sub)interface basis. –The GTS bit rate is gradually increased when the congestion is no longer present (no BECN packets are received anymore).

© 2001, Cisco Systems, Inc. QOS v1.0—4-36 GTS Frame Relay Congestion Adaptability Mechanisms Bit-rate adaptation: –The traffic shaping bit rate is reduced when a packet with a BECN bit is received in the T c. –The traffic shaping bit rate is increased if no BECN bits were received in the T c. FECN-to-BECN propagation: –A test packet with a BECN bit set is sent to the sender if a packet with an FECN bit set is received.

© 2001, Cisco Systems, Inc. QOS v1.0—4-37 An Example of BECN Integration BECN Integration Time Represented in Units of T c Inc Added Every T c in the Token Bucket Inc BECN traffic-shape rate traffic-shape adaptive BECN received at T c #1 and T c #3 Hypothesis: no idle traffic

© 2001, Cisco Systems, Inc. QOS v1.0—4-38 Congestion FECN-to-BECN Propagation SenderSender ReceiverReceiver If there is no reverse traffic, the switch is not able to set BECN in frames going back to sender. BECN in Q.922Test FECN Frame Relay Switch Frame Relay Switch

© 2001, Cisco Systems, Inc. QOS v1.0—4-39 Configuring Bit-Rate Adaptation Configures traffic shaping Frame Relay bit-rate adaptation bit-rate—lowest bit rate the traffic is shaped to in response to continuous BECN signals Default: one-half the specified traffic shaping rate Traffic shaping has to be enabled traffic-shape adaptive [bit-rate] Router(config-if)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-40 Configures the router to send Frame Relay TEST message with BECN bit set in response to receiving a frame with FECN bit set Can be used without adaptive traffic shaping Configuring FECN-to-BECN Propagation Sets FECN bit in all outgoing packets that have been delayed due to traffic shaping Use for debugging/simulation only traffic-shape fecn-adapt Router(config-if)# traffic-shape fecn-create Router(config-if)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-41 GTS Frame Relay Adaptation Design Conservative scenario: Set shaping rate to CIR Set minimum rate to MIR (or one-half CIR) Optimistic scenario: Set shaping rate to EIR Set minimum rate to CIR Realistic scenario: Set shaping rate to EIR Set minimum rate to MIR (or one-half CIR)

© 2001, Cisco Systems, Inc. QOS v1.0—4-42 Core Customer WAN GTS Frame Relay Adaptation Example interface serial 0/0 traffic-shape rate traffic-shape adaptive interface serial 0/0 traffic-shape rate traffic-shape adaptive EIR = 64 kbps CIR = 48 kbps Assumption: Frame Relay network is usually not congested.

© 2001, Cisco Systems, Inc. QOS v1.0—4-43 Summary Upon completing this lesson, you should be able to: Describe the GTS mechanism Describe the benefits and drawbacks of GTS Configure GTS on Cisco routers Monitor and troubleshoot GTS

© 2001, Cisco Systems, Inc. QOS v1.0—4-44 Lesson Review 1.What software queuing mechanisms are supported in combination with GTS? 2.Which queuing structure does GTS use? 3.What features does GTS include when it is used on Frame Relay interfaces?

Frame Relay Traffic Shaping © 2001, Cisco Systems, Inc. QOS v1.0—4-45

© 2001, Cisco Systems, Inc. QOS v1.0—4-46 Objectives Upon completing this lesson, you will be able to: Describe the FRTS mechanism Describe the benefits and drawbacks of FRTS Compare the GTS and FRTS mechanisms Configure FRTS on Cisco routers Monitor and troubleshoot FRTS

© 2001, Cisco Systems, Inc. QOS v1.0—4-47 Frame Relay Traffic Shaping Can be implemented on a per-VC basis (classification) Measures traffic rate of individual virtual circuits (metering) Delays packets of exceeding VCs (shaping) Dynamic traffic throttling on a per-VC basis (BECN or ForeSight) Enhanced queuing support on a per-VC basis (PQ, CQ or WFQ) Traffic Stream ClassifierMarker Shaper Dropper Meter

© 2001, Cisco Systems, Inc. QOS v1.0—4-48 FRTS Building Blocks Shaping Queue Shaping Queue Shaping Queue No Yes Enough Tokens? Enough Tokens? Enough Tokens? Enough Tokens? Enough Tokens? Enough Tokens? No classifier; shaping performed on individual VC Traffic for VCs that are not shaped Forwarder + Frame Relay Maps Forwarder + Frame Relay Maps Physical Interface Queue(s)

© 2001, Cisco Systems, Inc. QOS v1.0—4-49 FRTS Overview FRTS is multiprotocol. FRTS can use one of these queuing mechanisms as the shaping queue: –Priority queuing (PQ) –Custom queuing (CQ) –Weighted fair queuing (WFQ) FRTS can be implemented only in combination with WFQ on the interface. FRTS works on output only.

© 2001, Cisco Systems, Inc. QOS v1.0—4-50 GTS vs. FRTS Generic traffic shaping is equivalent to Frame Relay traffic shaping when it is configured on point-to-point Frame Relay subinterfaces. Generic Traffic ShapingFrame Relay Traffic Shaping Works on any (sub)interface Shapes traffic on (sub)interface basis Any physical interface queuing can be used Only WFQ can be used for shaping queue Works only on Frame Relay Shapes traffic of individual virtual circuits Only WFQ can be used on physical interface CQ, PQ, or WFQ can be used in shaping queue

© 2001, Cisco Systems, Inc. QOS v1.0—4-51 Configuring FRTS Define the shaping parameters (map-class): –Token bucket parameters –Frame Relay congestion adaptation –Shaping queue type Enable Frame Relay traffic shaping on physical interface Apply the shaping definition: –For all VCs on (sub)interface –For individual PVCs/SVCs

© 2001, Cisco Systems, Inc. QOS v1.0—4-52 Creating a Map Class Creates a new Frame Relay map class or starts editing existing map class Map class names are case sensitive map-class frame-relay name Router(config)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-53 Selects priority queuing as the shaping queue structure Define Map Class Shaping Queue Selects custom queuing as the shaping queue structure Selects WFQ as the shaping queue structure FRF.12 requires weighted fair queuing frame-relay priority-group number Router(config-map-class)# frame-relay custom-queue-list number Router(config-map-class)# frame-relay fair cdt max-queue rsvp-queues max-buf Router(config-map-class)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-54 Specifies the shaping parameters in CIR/B c /B e values T c is computed from CIR and B c Only outgoing values can be specified for FRTS Define Traffic Shaping Parameters Specifies only the CIR and peak rate T c is specified by the router B c and B e are computed from T c, average and peak rate frame-relay [in|out] cir bit-rate frame-relay [in|out] bc bits frame-relay [in|out] be bits frame-relay [in|out] cir bit-rate frame-relay [in|out] bc bits frame-relay [in|out] be bits Router(config-map-class)# frame-relay traffic-rate average-rate peak-rate Router(config-map-class)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-55 Enables adaptive shaping for the Frame Relay map class Congestion indication mechanism could be BECN or ForeSight (CLLM) Define Congestion Adaptation Mechanism Specifies the minimum bit rate for congestion adaptation algorithm frame-relay adaptive-shaping becn|foresight Router(config-map-class)# frame-relay mincir rate Router(config-map-class)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-56 Define Dedicated Queue for VoFR Packets Creates dedicated queue for VoFR packets VoFR queue has priority over regular queues configured on the same VC Specified bandwidth has to include L2 and VoFR overhead Voice calls over Frame Relay will not be placed unless the voice queue is configured Voice over FR call will be rejected if there is not enough bandwidth available in the voice queue frame-relay voice bandwidth bps queue depth Router(config-map-class)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-57 Enable FRTS on an Interface Enables Frame Relay traffic shaping on a physical interface No special queuing can be configured on the interface Weighted fair queuing is used as the physical interface queuing mechanism regardless of interface bandwidth frame-relay traffic-shaping Router(config-if)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-58 Applies the specified Frame Relay map class to all VCs configured on the specified (sub)interface Apply FRTS to a VC Applies the specified Frame Relay map class only to the specified DLCI Traffic for DLCIs that have no map class defined (on DLCI or on [sub]interface) is not shaped frame-relay class map-class-name Router(config-if)# frame-relay interface-dlci DLCI class map-class-name frame-relay interface-dlci DLCI class map-class-name Router(config-if)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-59 Frame Relay Traffic Shaping Example Core Customer WAN Customer uses different policies and queuing mechanisms for each DLCI. interface Serial1/1 frame-relay traffic-shaping ! interface Serial1/1.1 point-to-point frame-relay interface-dlci 101 class slow_vcs ! interface Serial1/1.2 point-to-point frame-relay interface-dlci 102 class fast_vcs ! map-class frame-relay fast_vcs frame-relay custom-queue-list 1 frame-relay traffic-rate ! map-class frame-relay slow_vcs frame-relay priority-group 1 frame-relay traffic-rate interface Serial1/1 frame-relay traffic-shaping ! interface Serial1/1.1 point-to-point frame-relay interface-dlci 101 class slow_vcs ! interface Serial1/1.2 point-to-point frame-relay interface-dlci 102 class fast_vcs ! map-class frame-relay fast_vcs frame-relay custom-queue-list 1 frame-relay traffic-rate ! map-class frame-relay slow_vcs frame-relay priority-group 1 frame-relay traffic-rate

© 2001, Cisco Systems, Inc. QOS v1.0—4-60 Frame Relay QoS Autosense Frame Relay QoS parameters are usually defined manually on the router. The same parameters are also carried in ELMI (CLLM) messages. QoS autosense allows the router to learn the DLCI QoS parameters from the switch: –ELMI must be configured on the router and the switch. –Only Cisco Frame Relay switches are supported.

© 2001, Cisco Systems, Inc. QOS v1.0—4-61 Configuring QoS Autosense Enables the Enhanced Local Management Interface feature Allows QoS parameters (CIR, B c, B e ) to be passed by the switch to the router automatically in ELMI messages frame-relay qos-autosense Router(config-if)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-62 Monitoring Frame Relay Traffic Shaping show frame-relay PVC: –Displays VC QoS and shaping parameters show traffic-shape statistics: –Displays GTS and FRTS statistics show traffic-shape queue: –Displays GTS and FRTS shaping queue contents

© 2001, Cisco Systems, Inc. QOS v1.0—4-63 Display PVC Information Router#show frame-relay pvc 20 PVC Statistics for interface Serial4/0 (Frame Relay DCE) DLCI = 20, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial4/0.1 input pkts output pkts in bytes out bytes dropped pkts 0 in FECN pkts 0 in BECN pkts 0 out FECN pkts 0 out BECN pkts 0 in DE pkts 0 out DE pkts 0 out bcast pkts out bcast bytes Shaping adapts to BECN pvc create time 1w3d, last time pvc status changed 1w3d cir bc be 0 limit 1000 interval 125 mincir byte increment 1000 BECN response yes pkts 1103 bytes pkts delayed 1091 bytes delayed shaping active traffic shaping drops 1136 Current fair queue configuration: Discard Dynamic Reserved threshold queue count queue count Output queue size 46/max total 50/drops 1136 Router#show frame-relay pvc 20 PVC Statistics for interface Serial4/0 (Frame Relay DCE) DLCI = 20, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial4/0.1 input pkts output pkts in bytes out bytes dropped pkts 0 in FECN pkts 0 in BECN pkts 0 out FECN pkts 0 out BECN pkts 0 in DE pkts 0 out DE pkts 0 out bcast pkts out bcast bytes Shaping adapts to BECN pvc create time 1w3d, last time pvc status changed 1w3d cir bc be 0 limit 1000 interval 125 mincir byte increment 1000 BECN response yes pkts 1103 bytes pkts delayed 1091 bytes delayed shaping active traffic shaping drops 1136 Current fair queue configuration: Discard Dynamic Reserved threshold queue count queue count Output queue size 46/max total 50/drops 1136 Displays VC QoS and shaping parameters show frame-relay pvc Router#

© 2001, Cisco Systems, Inc. QOS v1.0—4-64 Display Shaping Statistics Displays GTS and FRTS statistics show traffic-shape statistics Router# Router#show traffic-shape statistics Access Queue Packets Bytes Packets Bytes Shaping I/F List Depth Delayed Delayed Active Se4/ yes Se4/ no Router#show traffic-shape statistics Access Queue Packets Bytes Packets Bytes Shaping I/F List Depth Delayed Delayed Active Se4/ yes Se4/ no

© 2001, Cisco Systems, Inc. QOS v1.0—4-65 Display Shaping Queue Information Displays GTS and FRTS shaping queue contents show traffic-shape queue Router# Router#show traffic-shape queue Traffic queued in shaping queue on Serial4/0.1 dlci 20 Queueing strategy: weighted fair Queueing Stats: 46/50/64/1377 (size/max total/threshold/drops) Conversations 1/2/16 (active/max active/max total) Reserved Conversations 0/0 (allocated/max allocated) (depth/weight/discards/tail drops/interleaves) 46/32384/1377/0/0 Conversation 5, linktype: ip, length: 1504 source: , destination: , id: 0x00F4, ttl: 255, prot: 1 Router#show traffic-shape queue Traffic queued in shaping queue on Serial4/0.1 dlci 20 Queueing strategy: weighted fair Queueing Stats: 46/50/64/1377 (size/max total/threshold/drops) Conversations 1/2/16 (active/max active/max total) Reserved Conversations 0/0 (allocated/max allocated) (depth/weight/discards/tail drops/interleaves) 46/32384/1377/0/0 Conversation 5, linktype: ip, length: 1504 source: , destination: , id: 0x00F4, ttl: 255, prot: 1

© 2001, Cisco Systems, Inc. QOS v1.0—4-66 Display Shaping Queue Information (cont.) PE_2#show traffic-shape queue Traffic queued in shaping queue on Serial4/0.1 dlci 20 Queueing strategy: priority-group 1 Queueing Stats: high 16/20/19 (queue/size/max total/drops) Packet 1, linktype: ip, length: 1504, flags: 0x source: , destination: , id: 0x0141, ttl: 255, prot: 1 data: 0x0800 0x9105 0x2659 0x1F89 0x0000 0x0000 0x3819 0x223C 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD Packet 2, linktype: ip, length: 1504, flags: 0x source: , destination: , id: 0x0141, ttl: 255, prot: 1 data: 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD PE_2#show traffic-shape queue Traffic queued in shaping queue on Serial4/0.1 dlci 20 Queueing strategy: priority-group 1 Queueing Stats: high 16/20/19 (queue/size/max total/drops) Packet 1, linktype: ip, length: 1504, flags: 0x source: , destination: , id: 0x0141, ttl: 255, prot: 1 data: 0x0800 0x9105 0x2659 0x1F89 0x0000 0x0000 0x3819 0x223C 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD Packet 2, linktype: ip, length: 1504, flags: 0x source: , destination: , id: 0x0141, ttl: 255, prot: 1 data: 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD 0xABCD

© 2001, Cisco Systems, Inc. QOS v1.0—4-67 Summary Upon completing this lesson, you should be able to: Describe the FRTS mechanism Describe the benefits and drawbacks of FRTS Compare the GTS and FRTS mechanisms Configure FRTS on Cisco routers Monitor and troubleshoot FRTS

© 2001, Cisco Systems, Inc. QOS v1.0—4-68 Lesson Review 1.What are the main differences between GTS and FRTS? 2.Where can FRTS be used? 3.What classification options does FRTS have?

Committed Access Rate © 2001, Cisco Systems, Inc. QOS v1.0—4-69

© 2001, Cisco Systems, Inc. QOS v1.0—4-70 Objectives Upon completing this lesson, you will be able to: Describe the CAR mechanism Describe the benefits and drawbacks of CAR Describe the differences between CAR, GTS, and FRTS Configure CAR on Cisco routers Monitor and troubleshoot CAR

© 2001, Cisco Systems, Inc. QOS v1.0—4-71 Committed Access Rate Primarily intended for rate limiting Can be used on inbound and outbound traffic Does not queue (delay) packets Can also mark packets Can be implemented for differentiated marking ClassifierMarker Dropper Meter Inbound or Outbound

© 2001, Cisco Systems, Inc. QOS v1.0—4-72 CAR on Input and Output Inbound ClassifierMarker Dropper Meter Outbound ClassifierMarkerDropper Meter Forwarding Queuing CAR on input is processed just before forwarding (most other QoS mechanisms are processed before CAR). CAR on output is processed immediately after forwarding (most other QoS mechanisms are processed after CAR).

© 2001, Cisco Systems, Inc. QOS v1.0—4-73 CAR Implementation The software queue may have no function if the sum of all CAR rates is less than the link bandwidth. Software Queue (FIFO, PQ, CQ, WFQ,...) Software Queue (FIFO, PQ, CQ, WFQ,...) Hardware Queue (FIFO) Hardware Queue (FIFO) Dispatches packets at line rate Bypasses the software queue if it is empty and there is room in the hardware queue CAR Dispatches packets at configured rate

© 2001, Cisco Systems, Inc. QOS v1.0—4-74 Interface-Wide CAR Diagram Class 1? Class 2? Class n? CAR continue transmit drop Output Queue or Forward CAR has three different actions: –Transmit –Continue –Drop

© 2001, Cisco Systems, Inc. QOS v1.0—4-75 CAR Diagram Meter Conforms? Set IP Precedence? Set DSCP? Set MPLS Experimental? Set QoS group? Mark? Transmit? Yes / No Set IP Precedence Set DSCP Set MPLS Experimental Set QoS Group Continue? Drop? Yes No Forward or Enqueue Go to Next CAR Command Marking depends on whether the packet conforms to or exceeds the policy. Yes

© 2001, Cisco Systems, Inc. QOS v1.0—4-76 Configuring CAR Specifies all four conditioner elements for a particular traffic class Repeat this command for different classes of traffic If a match is not found, the default action is to transmit rate-limit {input | output} [access-group [rate-limit] #acl | qos-group number | dscp dscp] mean-rate B c B e conform-action { drop | transmit | continue | set-prec-transmit value | set-prec-continue value | set-qos-transmit value | set-qos-continue value set-dscp-transmit value | set-dscp-continue value | set-mpls-transmit value | set-mpls-continue value } exceed-action { drop | transmit | continue | set-prec-transmit value | set-prec-continue value | set-qos-transmit value | set-qos-continue value set-dscp-transmit value | set-dscp-continue value | set-mpls-transmit value | set-mpls-continue value } rate-limit {input | output} [access-group [rate-limit] #acl | qos-group number | dscp dscp] mean-rate B c B e conform-action { drop | transmit | continue | set-prec-transmit value | set-prec-continue value | set-qos-transmit value | set-qos-continue value set-dscp-transmit value | set-dscp-continue value | set-mpls-transmit value | set-mpls-continue value } exceed-action { drop | transmit | continue | set-prec-transmit value | set-prec-continue value | set-qos-transmit value | set-qos-continue value set-dscp-transmit value | set-dscp-continue value | set-mpls-transmit value | set-mpls-continue value } Router(config-if)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-77 CAR Classification IP packets are classified: –Based on their direction (input or output) Optional classification based on: –Numbered IP access list (standard or extended) –IP Precedence rate-limit access list –MAC address rate-limit access list –QoS group set by a previous conditioner in the same node –DSCP rate-limit {input | output} [access-group [rate-limit] #acl | qos-group number | dscp dscp]... rate-limit {input | output} [access-group [rate-limit] #acl | qos-group number | dscp dscp]... Router(config-if)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-78 Null CAR Classifier Selects packets in ingress or egress direction that have not been classified with any previous rate-limit commands on this interface Usually used as the last rate-limit command on an interface rate-limit {input | output}... Router(config-if)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-79 CAR Classifier Based on IP Access List Configures an IP access list to be used as a packet classifier Classifies packets received over an interface with the IP access list Classification based on IP Precedence can be done with IP access list rate-limit {input | output} access-group number... Router(config-if)# access-list acl-index {deny | permit} source [source-wildcard] access-list acl-index {deny | permit} protocol source source- wildcard destination destination-wildcard [precedence precedence] [tos tos] [dscp dscp] [log] access-list acl-index {deny | permit} source [source-wildcard] access-list acl-index {deny | permit} protocol source source- wildcard destination destination-wildcard [precedence precedence] [tos tos] [dscp dscp] [log] Router(config)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-80 CAR Classifier Based on IP Precedence The IP Precedence classifier uses rate-limit access lists from 1 to 99 to match on IP Precedence values. rate-limit {input | output} access-group rate-limit number... Router(config-if)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-81 IP Precedence-Based Rate-Limit Access List ACL index is between 1 and 99 Matches packets with specified IP Precedence Only one line is allowed in the access list ACL index is between 1 and 99 Matches packets that match any precedence value specified in the mask Precedence mask has one bit for each precedence value (Bit 0 = Precedence 0) access-list rate-limit acl-index precedence Router(config)# access-list rate-limit acl-index mask precedence-mask Router(config)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-82 CAR Classifier Based on Upstream MAC Address The upstream MAC address classifier uses rate-limit access lists from 100 to 199 to match on the MAC address of an upstream router or host. rate-limit {input | output} access-group rate-limit number... Router(config-if)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-83 MAC Address Rate-Limit Access List ACL index is between 100 and 199 Matches packets received from upstream neighbor with specified MAC address Only the MAC address is allowed in the access list (each upstream neighbor requires a different rate- limit statement) access-list rate-limit acl-index mac-address Router(config)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-84 QoS Group CAR Classifier Selects IP packets already marked in this node with specified QoS group QoS group marking can be done through: –Policy-based routing –CEF marking based on QPPB –Inbound rate limit on another interface –Inbound class-based marking on another interface Available only on high-end platforms rate-limit {input | output} qos-group number... Router(config-if)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-85 DSCP-Based CAR Classifier Selects IP packets marked with the specified DiffServ code point DSCP marking could be done through: –Rate limiting on another interface or router –Class-based marking on another interface or router rate-limit {input | output} dscp dscp... Router(config-if)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-86 CAR Meter The rate-limit meter measures the contract compliance of a traffic class selected with a classifier. A modified token bucket algorithm is used: –mean-rate specifies average traffic rate. –B c specifies the normal burst size. –B e specifies the excess burst size. The token bucket size is defined by B e alone. rate-limit {input | output} [access-group [rate-limit] number | qos-group number | dscp dscp] mean-rate B c B e... rate-limit {input | output} [access-group [rate-limit] number | qos-group number | dscp dscp] mean-rate B c B e... Router(config-if)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-87 CAR Actions CAR actions can be split into two subactions: –Marking action –Processing action Marking actions support the setting of: –IP Precedence –DSCP –MPLS experimental bits –QoS group Processing actions: –Transmit—packet is transmitted –Continue—packet is also processed by the next “rate-limit” command –Drop—packet is dropped

© 2001, Cisco Systems, Inc. QOS v1.0—4-88 CAR Actions (cont.) Processing actions “transmit,” “continue,” and “drop” can be used as standalone actions. Processing actions “transmit” and “continue” can be combined with marking actions (set-mark_action-proc_action): –set-prec-transmit –set-qos-transmit –set-mpls-transmit –set-dscp-transmit –set-prec-continue –set-qos-continue –set-mpls-continue –set-dscp-continue

© 2001, Cisco Systems, Inc. QOS v1.0—4-89 CAR Actions (cont.) Conforming and exceeding packets can be configured with different actions. There are three typical uses of CAR: –Pure rate limiting: Transmit conforming packets Drop exceeding packets –Differentiated marking: Transmit conforming packets with marker value x (e.g., IP Precedence 3) Transmit exceeding packets with marker value y (e.g., IP Precedence 2) –Pure marking: Transmit confirming and exceeding packets with the same marker value

© 2001, Cisco Systems, Inc. QOS v1.0—4-90 Displaying CAR Parameters and Statistics Router#show interfaces serial 0/0 rate-limit Serial0 Input matches: qos-group 4 params: bps, limit, extended limit conformed 0 packets, 0 bytes; action: transmit exceeded 0 packets, 0 bytes; action: set-prec-transmit 0 last packet: ms ago, current burst: 0 bytes last cleared 00:00:59 ago, conformed 0 bps, exceeded 0 bps Output matches: access-group 181 params: 8000 bps, 8000 limit, extended limit conformed 19 packets, bytes; action: set-prec-transmit 3 exceeded 5 packets, 7520 bytes; action: drop last packet: ms ago, current burst: bytes last cleared 00:03:01 ago, conformed 0 bps, exceeded 0 bps Router#show interfaces serial 0/0 rate-limit Serial0 Input matches: qos-group 4 params: bps, limit, extended limit conformed 0 packets, 0 bytes; action: transmit exceeded 0 packets, 0 bytes; action: set-prec-transmit 0 last packet: ms ago, current burst: 0 bytes last cleared 00:00:59 ago, conformed 0 bps, exceeded 0 bps Output matches: access-group 181 params: 8000 bps, 8000 limit, extended limit conformed 19 packets, bytes; action: set-prec-transmit 3 exceeded 5 packets, 7520 bytes; action: drop last packet: ms ago, current burst: bytes last cleared 00:03:01 ago, conformed 0 bps, exceeded 0 bps Displays CAR parameters and statistics show interfaces intf rate-limit Router#

© 2001, Cisco Systems, Inc. QOS v1.0—4-91 Display Rate-Limit Access Lists Router#show access-lists rate-limit Rate-limit access list 10 1 Rate-limit access list 11 mask 81 Rate-limit access list ABCD Router#show access-lists rate-limit Rate-limit access list 10 1 Rate-limit access list 11 mask 81 Rate-limit access list ABCD List rate-limit access lists show access-lists rate-limit Router(config)#

© 2001, Cisco Systems, Inc. QOS v1.0—4-92 CAR: Limiting Example #1 A service provider connects all its customers via 2 Mbps physical leased lines (or ADSL links) and uses CAR to limit the actual amount of traffic the user can send or receive. In addition, several differentiated services could be provided based on customer needs.

© 2001, Cisco Systems, Inc. QOS v1.0—4-93 CAR: Limiting Example #1 (cont.) ISP Customer 2 Mbps Customer 2 Mbps NAP Internet interface serial 0/0 rate-limit input conform-action transmit exceed-action drop rate-limit output conform-action transmit exceed-action drop interface serial 0/0 rate-limit input conform-action transmit exceed-action drop rate-limit output conform-action transmit exceed-action drop

© 2001, Cisco Systems, Inc. QOS v1.0—4-94 CAR: Limiting and Marking Example #2 Web traffic is limited to 512 kbps and transmitted with higher precedence: –Excess web traffic is classified as regular traffic. All other traffic is limited to 256 kbps and transmitted with Precedence 0: –Excess traffic is dropped. –Burst size is 16,000 bytes. –Excess burst size is 24,000 bytes.

© 2001, Cisco Systems, Inc. QOS v1.0—4-95 CAR: Limiting and Marking Example #2 (cont.) ISP Customer 2 Mbps NAP Internet interface serial 0/0 rate-limit input access-group conform-action set-prec-transmit 1 exceed-action continue rate-limit input conform-action set-prec-transmit 0 exceed-action drop rate-limit output access-group conform-action set-prec-transmit 1 exceed-action continue rate-limit output conform-action set-prec-transmit 0 exceed-action drop ! access-list 101 permit tcp any any eq www access-list 101 permit tcp any eq www any interface serial 0/0 rate-limit input access-group conform-action set-prec-transmit 1 exceed-action continue rate-limit input conform-action set-prec-transmit 0 exceed-action drop rate-limit output access-group conform-action set-prec-transmit 1 exceed-action continue rate-limit output conform-action set-prec-transmit 0 exceed-action drop ! access-list 101 permit tcp any any eq www access-list 101 permit tcp any eq www any

© 2001, Cisco Systems, Inc. QOS v1.0—4-96 CAR: Limiting Example #3 The customer can send or receive up to 128 kbps of premium traffic: –Premium traffic is marked with Precedence 1. –Excess premium traffic is dropped. Non premium (best-effort) traffic is not rate- limited

© 2001, Cisco Systems, Inc. QOS v1.0—4-97 CAR: Limiting Example #3 (cont.) ISP Customer 2 Mbps Customer 2 Mbps NAP Internet interface serial 0/0 rate-limit input access-group rate-limit conform-action transmit exceed-action drop rate-limit output access-group rate-limit conform-action transmit exceed-action drop ! access-list rate-limit 13 1 interface serial 0/0 rate-limit input access-group rate-limit conform-action transmit exceed-action drop rate-limit output access-group rate-limit conform-action transmit exceed-action drop ! access-list rate-limit 13 1

© 2001, Cisco Systems, Inc. QOS v1.0—4-98 CAR: Precedence Spoofing Example #4 If a customer is trying to spoof a service provider with high-precedence traffic, the traffic is dropped: –Drop all non-Precedence-0 traffic received from a customer. ISP Customer 2 Mbps Customer 2 Mbps NAP Internet interface serial 0/0 rate-limit input access-group rate-limit conform-action drop exceed-action drop ! access-list rate-limit 1 mask FE interface serial 0/0 rate-limit input access-group rate-limit conform-action drop exceed-action drop ! access-list rate-limit 1 mask FE

© 2001, Cisco Systems, Inc. QOS v1.0—4-99 CAR: Limiting Example #5 Application: Web server collocation: –The customer can locate a server at service provider premises (switched LAN). –CAR is used to limit the amount of traffic the web server can generate. –Unknown traffic that is rate-limited to 64 kbps to allow remote configuration of new servers. Alternate application: central site in an enterprise network

© 2001, Cisco Systems, Inc. QOS v1.0—4-100 CAR: Limiting Example #5 (cont.) Server LAN Switch Server Distribution Router Core Network interface FastEthernet 0/0 rate-limit input access-group rate-limit conform-action transmit exceed-action drop rate-limit output access-group rate-limit conform-action transmit exceed-action drop rate-limit input conform-action transmit exceed-action drop rate-limit output conform-action transmit exceed-action drop ! access-list rate-limit ae.0123.abcd ! Server MAC address interface FastEthernet 0/0 rate-limit input access-group rate-limit conform-action transmit exceed-action drop rate-limit output access-group rate-limit conform-action transmit exceed-action drop rate-limit input conform-action transmit exceed-action drop rate-limit output conform-action transmit exceed-action drop ! access-list rate-limit ae.0123.abcd ! Server MAC address

© 2001, Cisco Systems, Inc. QOS v1.0—4-101 CAR: Marking Example #6 Core Customer WAN interface ethernet 0/0 rate-limit input conform-action set-prec-transmit 2 exceed-action drop ! interface ethernet 0/1 rate-limit input conform-action set-prec-transmit 0 exceed-action drop ! interface ethernet 0/0 rate-limit input conform-action set-prec-transmit 2 exceed-action drop ! interface ethernet 0/1 rate-limit input conform-action set-prec-transmit 0 exceed-action drop ! CAR can be used purely for marking purposes.

© 2001, Cisco Systems, Inc. QOS v1.0—4-102 CAR: Marking Example #7 Core Customer WAN interface ethernet 0/0 rate-limit input access-group conform-action set-prec-transmit 2 exceed-action drop rate-limit input access-group conform-action set-prec-transmit 1 exceed-action drop rate-limit input conform-action set-prec-transmit 0 exceed-action drop ! access-list 101 permit tcp any any eq telnet access-list 102 permit tcp any any eq www interface ethernet 0/0 rate-limit input access-group conform-action set-prec-transmit 2 exceed-action drop rate-limit input access-group conform-action set-prec-transmit 1 exceed-action drop rate-limit input conform-action set-prec-transmit 0 exceed-action drop ! access-list 101 permit tcp any any eq telnet access-list 102 permit tcp any any eq www

© 2001, Cisco Systems, Inc. QOS v1.0—4-103 Summary Upon completing this lesson, you should be able to: Describe the CAR mechanism Describe the benefits and drawbacks of CAR Describe the differences between CAR, GTS, and FRTS Configure CAR on Cisco routers Monitor and troubleshoot CAR

© 2001, Cisco Systems, Inc. QOS v1.0—4-104 Lesson Review 1.What classification options does CAR support? 2.What are the main differences between CAR and traffic shaping? 3.Where can CAR be implemented?

© 2001, Cisco Systems, Inc. QOS v1.0—4-105 Module Summary After completing this module, you should be able to perform the following tasks: Describe and configure generic traffic shaping (GTS) Describe and configure Frame Relay traffic shaping (FRTS) Describe and configure committed access rate (CAR) Name other mechanisms that support traffic shaping and policing (class-based policing and class-based shaping)

© 2001, Cisco Systems, Inc. IP QoS Traffic Shaping and Policing-106