© 2001, cisco systems, inc. ip over atm. © 2001, cisco systems, inc. qos v1.0—10-2 objectives...

© 2001, Cisco Systems, Inc.

IP over ATM

© 2001, Cisco Systems, Inc. QOS v1.0—10-2

ObjectivesObjectives

Upon completing this module, you will be able to: • List the requirements of IP QoS in combination with ATM QoS

• Describe the hardware and software requirements for advanced IP QoS mechanisms on ATM interfaces

• Describe per-VC queuing

• Describe and configure per-VC WRED

• Describe and configure VC bundling

• Describe and configure per-VC CBWFQ

• Describe RSVP-to-SVC mapping

• Monitor and troubleshoot IP QoS on ATM interfaces

Introduction to IP over ATM

Introduction to IP over ATM




Upon completing this lesson, you will be able to: • Describe the QoS problems related to use of

ATM networks




IP vs. ATMTechnology Comparison

IP vs. ATMTechnology Comparison

IP• Connectionless

• Per-packet QoS (IP Precedence)

• Small number of service classes

• IP Precedence and DSCP do not encode service parameters

ATM• Connection oriented

• Per-connection (virtual circuit) QoS

• Large number of QoS traffic classes (CBR, VBR, UBR, ABR)

• Rich traffic parameters (PCR, MCR, SCR, etc.) specified for each VC


Integrating IP and ATMIntegrating IP and ATM

• Overlay model (ATM forum):– ATM VCs are manually established between pairs

of devices.

– IP packets are sent across these VCs.

– ATM switches are not IP-aware.

• Peer model (MPLS):– ATM switches are IP-aware on the control

(but not data) plane.

– ATM VCs are established on-demand based on IP routing tables.


IP QoS and ATMIP QoS and ATM

• Routers can be interconnected over an ATM backbone using different ATM services:– UBR–congestion management virtually impossible

because routers are allowed to transmit packets at line speed

– VBR–congestion management easier, but requires conservative setting of transmit rates

– CBR–similar to VBR from IP perspective

– ABR–pushes congestion back to the source, requiring dynamic adjustment to available bandwidth


UBR Virtual CircuitsUBR Virtual Circuits

• Solution:– Set CLP on the router based on IP information to minimize the

effect of cell drops

No congestion:Router allowed to send at full speed

No congestion:Router allowed to send at full speed

RandomCLP marking

RandomCLP marking

CongestionCongestion

Unintelligent drops based on CLP

Unintelligent drops based on CLP


VBR Virtual CircuitsVBR Virtual Circuits

• Solution:– Set CLP on the router based on IP information– Use available IP QoS mechanisms to manage congestion at the source

Router is sending at configured rate.Router is sending at configured rate.

Congestion!Congestion!

Congestion is possible.

Congestion is possible.

Unintelligent random drops

Unintelligent random drops


CBR and ABR Virtual CircuitsCBR and ABR Virtual Circuits

• Solution:– Use available IP QoS mechanism to handle congestion at the

source

Router is sending at configured rate.Router is sending at configured rate.

Congestion!Congestion!


Congestion Management in ATM Networks

Congestion Management in ATM Networks

• Congestion management on routers should be performed on a per-VC basis.

• Design options:– Make sure there is no congestion in the ATM

network (ABR, CBR, VBR) and use IP QoS mechanisms at the source (CBWFQ, WRED)

– Mark less important packets with the CLP bit in case there is congestion in the ATM network (class-based policing, class-based marking)

– Use multiple parallel (per-CoS) virtual circuits with ATM QoS (VC bundling)


Per-VC QueuingPer-VC Queuing

• Per-VC queuing is required in order to handle congestion on a per-VC basis.

• Per-VC queuing prevents head-of-line blocking by slow virtual circuits.

ATM Port AdapterATM Port Adapter

VC 1/50

VC 1/64

VC 1/76

VC 1/39

ATM InterfaceCell queue VC 1/50

Cell queue VC 1/64

Cell queue VC 1/76

Cell queue VC 1/39

VIP MemoryVIP Memory

Frame queue VC 1/50

Frame queue VC 1/64

Frame queue VC 1/76

Frame queue VC 1/39

ATM Hardware Shaping

ATM Hardware Shaping

Per-VC Queuing with Per-VC Congestion

Management

Per-VC Queuing with Per-VC Congestion

Management


SummarySummary

Upon completing this lesson, you should be able to:• Describe the QoS problems related to use of

ATM networks




Review QuestionsReview Questions

1. What are the main differences between IP and ATM?

2. Which QoS services does ATM support?

3. How should congestion be handled when an ATM backbone is used?

4. Why is per-VC queuing so important?


Per-VC WREDPer-VC WRED




Upon completing this lesson, you will be able to: • Describe per-VC WRED

• Configure per-VC WRED

• Monitor and troubleshoot per-VC WRED


Per-VC WREDPer-VC WRED

• A single ATM VC is established over an ATM cloud between a pair of routers:

–ABR, VBR, UBR, or CBR

–Using UBR will not result in proper operation, as there is no ATM shaping in UBR

• All IP traffic toward a next-hop router is forwarded across a single ATM VC

• Congestion is managed entirely on the IP layer using WRED on each individual ATM VC, resulting in differentiated IP services


Per-VC WRED: Intelligent IP Packet Discard

Per-VC WRED: Intelligent IP Packet Discard

VIP2-50 PA-A3-XX

Per-VCPer-VCWRED:WRED:

Intelligent DiscardIntelligent Discard

Per-VCPer-VCWRED:WRED:

Intelligent DiscardIntelligent Discard

Threshold Exceeded

VC1

VC2

VC3

No DiscardNo Discardon PAon PA

No DiscardNo Discardon PAon PA

Traffic Traffic ShapingShapingTraffic Traffic

ShapingShaping

Per-VCPer-VCQueuesQueuesPer-VCPer-VCQueuesQueues


Configuring Per-VC WREDConfiguring Per-VC WRED

• Follow these configuration steps to enable per-VC WRED:

–Create a Random Detect Group template with a WRED profile

–Apply the WRED template to an ATM interface or to individual ATM VCs

–Verify and monitor the operation of per-VC WRED


random-detect-group namerandom-detect-group name

Router(config)#

• Creates a WRED template

Create and Configure RED-groupCreate and Configure RED-group

exponential-weighting-constant expexponential-weighting-constant exp

Router(cfg-red-group)#

• Defines WRED weighting constant• Default: 9

precedence IP-prec min-threshold max-threshold prob-denominatorprecedence IP-prec min-threshold max-threshold prob-denominator

Router(cfg-red-group)#

• Defines RED profile for specified precedence• Default: as with per-interface WRED


Apply WRED Group to an ATM PVC

Apply WRED Group to an ATM PVC

random-detect [attach random-detect-group]random-detect [attach random-detect-group]

Router(config-if-atm-vc)#

• Enables WRED on a PVC using the selected WRED profile

• Default WRED parameters are used if the group name is omitted or refers to a nonexistent group

• Default: No WRED is used on the ATM PVC


show queueing random-detect [interface intf [vc vpi vci ]] show queueing random-detect [interface intf [vc vpi vci ]] Router#

• Displays WRED parameters for an ATM (sub)interface or individual VC

Monitoring and Troubleshooting Per-VC WRED

Monitoring and Troubleshooting Per-VC WRED

show queueing interface interface [vc vpi vci]show queueing interface interface [vc vpi vci]Router#

• Displays interface queues or individual per-VC queue


WRED Case StudyWRED Case Study

• WRED is applied to ATM PVCs in a network with these IP Precedence definitions:IP Prec. Meaning

0 High-loss, best-effort traffic1 Low-loss, best-effort traffic2 Premium traffic outside of the

contract3 Premium traffic in the contract4 Unused5 Voice over IP6 Routing protocol traffic7 Routing protocol traffic

• The WRED queue length is 100 packets for PVCs with SCR > 10 Mbps, and 40 packets for slower PVCs.


Case Study WRED ProfileCase Study WRED ProfileP

ack

et

Dis

card

Pro

ba

bili

ty

AverageQueue Size

0.1

RSVP

15

10

20

25

30

35

37

Precedence 2

Precedence 0

Precedence 3

Precedence 1

VoIP

Routing


Router ConfigurationRouter Configuration

• Step #1: Configure WRED profile for slow PVCs

random-detect-group slow-wred-profile precedence 0 10 25 10 precedence 1 20 40 10 precedence 2 15 25 10 precedence 3 25 40 10 precedence 4 1 10 10 precedence 5 35 40 10 precedence 6 30 40 10 precedence 7 30 40 10

random-detect-group slow-wred-profile precedence 0 10 25 10 precedence 1 20 40 10 precedence 2 15 25 10 precedence 3 25 40 10 precedence 4 1 10 10 precedence 5 35 40 10 precedence 6 30 40 10 precedence 7 30 40 10


Router Configuration (cont.)Router Configuration (cont.)

• Step #2: Configure WRED profile for fast PVCs

random-detect-group fast-wred-profile precedence 0 25 62 10 precedence 1 50 100 10 precedence 2 37 62 10 precedence 3 62 100 10 precedence 5 87 100 10 precedence 4 1 10 10 precedence 6 75 100 10 precedence 7 75 100 10

random-detect-group fast-wred-profile precedence 0 25 62 10 precedence 1 50 100 10 precedence 2 37 62 10 precedence 3 62 100 10 precedence 5 87 100 10 precedence 4 1 10 10 precedence 6 75 100 10 precedence 7 75 100 10



• Step #3: Apply WRED profile on various PVCs

interface ATM11/0/0 ip address 17.1.0.1 255.255.255.0 atm pvc 50 0 50 aal5snap 25000 50000 10 inarp

random-detect fast-wred-profile!interface ATM11/0/0.100 point-to-point ip address 17.1.1.1 255.255.255.252 atm pvc 100 0 100 aal5snap 17000 34000 10 inarp


random-detect slow-wred-profile

interface ATM11/0/0 ip address 17.1.0.1 255.255.255.0 atm pvc 50 0 50 aal5snap 25000 50000 10 inarp



random-detect slow-wred-profile


SummarySummary

Upon completing this lesson, you should be able to:• Describe per-VC WRED

• Configure per-VC WRED

• Monitor and troubleshoot per-VC WRED



1. What are the benefits of per-VC WRED?

2. What are the configuration steps needed to enable per-VC WRED?


VC BundlingVC Bundling




Upon completing of this lesson, you will be able to: • Describe VC bundling

• Configure VC bundling

• Monitor and troubleshoot VC bundling


VC BundlingVC Bundling

• VC bundling is a solution in which ATM QoS mechanisms are used.

• Classes of service are identified by IP Precedence.

• Each VC uses an ATM service based on the requirements of the class.

• Routers automatically map packets in VCs based on their IP Precedence value.

• Multiple parallel VCs are needed for each IP adjacency.


VC Bundling Case StudyVC Bundling Case Study

ATM VC ATM VC Type IP Prec.Control VC (routing updates) VBR 6-7Voice CBR 5VPN traffic VBR 4Premium Internet traffic VBR 2-3Best-effort Internet traffic ABR 0-1

Control (Routing) Control (Routing)

VoiceVoice

VPN TrafficVPN Traffic

Premium InternetPremium Internet

Best-Effort InternetBest-Effort Internet



VoiceVoice




VC Bundling Routing Adjacency

VC Bundling Routing Adjacency

The whole bundle is treated as one routing adjacency and is covered by a single ATM map.The whole bundle is treated as one routing adjacency and is covered by a single ATM map.

Routing protocol packets are exchanged over the control VC as they are sent with IP Precedence 6.Routing protocol packets are exchanged over the control VC as they are sent with IP Precedence 6.

Each VC has its own hardware queue in the router, managed with WRED.Each VC has its own hardware queue in the router, managed with WRED.


VC ProvisioningVC Provisioning

• VCs are dimensioned based on expected load for the precedence level(s) transported on that VC

• More isolation between classes

• At the expense of:

–Less statistical multiplexing

–More complex provisioning/engineering


VC Bundle ManagementVC Bundle Management

• The integrity of each individual VC is verified with end-to-end OAM cells.


VoiceVoice





VC Bundle Management (cont.)VC Bundle Management (cont.)


VoiceVoice



• Two ways of handling loss of VC in the bundle:– The whole bundle is declared down– Traffic from the lost VC is bumped onto another VC

• The IP routing model does not allow the traffic for a single precedence value to be rerouted over another path.


VC BumpingVC Bumping

• VC bumping = possibility for traffic mapped to VC X to be forwarded onto VC Y, in case of failure of X.

• Traffic can be bumped based on implicit or explicit rules.

• An individual VC or a group of VCs can be protected.


Implicit BumpingImplicit Bumping


VoiceVoice



• Traffic from the lost VC is bumped onto the VC carrying traffic with the next lower precedence.


Reject BumpingReject Bumping

• Problem: Control traffic shall not be bumped onto voice VC (implicit rule).

• Solution #1: Voice VC can reject bumping; bumped traffic goes to next lower VC.

VoiceVoice




Rejectsbumping


Voice

VPN Traffic

Premium Internet

Best-Effort Internet

Explicit BumpingExplicit Bumping

• Problem: Control traffic shall not be bumped onto voice VC (implicit rule).

• Solution #2: Specify explicitly onto which VC the traffic will be bumped.

Bump explicitlyto Precedence 0


Bundle Failure ScenariosBundle Failure Scenarios

• Problem: Under default settings, the whole bundle is declared down if the lowest-precedence VC is lost.

• Solution: Be sure that the lowest-precedence VC is always bumped via the explicit bumping rule.

Precedence 0 trafficcannot be implicitly

bumped.

Whole bundleis lost.




VoiceVoice

When a bundle is declared down, no traffic is forwarded out of the bundle,

even if some VCs are still up.

When a bundle is declared down, no traffic is forwarded out of the bundle,

even if some VCs are still up.


Protected VCProtected VC

• Problem: Voice traffic shall not be bumped onto data VC.

• Solution: Failure of the protected VC brings down the whole bundle; IP routing will find an alternate path.

Voice VC isprotected VC.







Protected GroupProtected Group

• Problem: If most of the VCs are lost, it does not make sense to bump traffic onto low-volume VCs.

• Solution: Failure of all VCs in a protected group will bring down the bundle.



VoiceVoice

All VCs in theprotected group

are lost.


VC Bumping—Final DetailsVC Bumping—Final Details

• If the VC that carries the bumped traffic fails, the traffic will follow the bumping rules specified for that VC.

• Traffic is restored to the original VC when the VC carrying the bumped traffic.


Configuring VC BundlingConfiguring VC Bundling

• Configuration steps:

–Configure ATM interface

–Configure VC bundle

–Configure individual VCs in the bundle

–Optionally, use VC-class object as VC parameter template


VC Bundle ParametersVC Bundle Parameters

• Parameters configurable on the VC bundle or vc-class template applied to the bundle:– Layer 3 ATM maps

– Encapsulation

– Broadcast propagation

– ATM Inverse ARP

– OAM management

– Global bumping rules


Individual VC ParametersIndividual VC Parameters

• Parameters configurable on individual VCs in the bundle (or vc-class template):

– IP Precedence mapping

–VC protection mode

–VC bumping rules

–ATM VC mode and ATM QoS parameters

–WRED group


Configuring a Bundle-Wide VC Class

Configuring a Bundle-Wide VC Class

class-vc vc-class-nameoam-bundle [manage] [frequency]bump {implicit | explicit precedence-level | traffic}encapsulation atm-encapprotocol atm-map-parameters …[no] broadcastinarp timeout

class-vc vc-class-nameoam-bundle [manage] [frequency]bump {implicit | explicit precedence-level | traffic}encapsulation atm-encapprotocol atm-map-parameters …[no] broadcastinarp timeout

Router(config)#

• Configures all parameters that can be specified on an ATM VC bundle in a VC class


Configuring an ATM VC BundleConfiguring an ATM VC Bundle

bundle bundle-nameclass vc-class-nameoam-bundle [manage] [frequency]bump {implicit | explicit precedence-level | traffic}encapsulation atm-encapprotocol atm-map-parameters …[no] broadcastinarp timeout

bundle bundle-nameclass vc-class-nameoam-bundle [manage] [frequency]bump {implicit | explicit precedence-level | traffic}encapsulation atm-encapprotocol atm-map-parameters …[no] broadcastinarp timeout

Router(config-if)#

• Configures an ATM VC bundle• If a vc-class template is applied to the bundle, the

bundle inherits parameters specified in the vc-class template

• Individual parameters specified in the vc-class template can be overwritten by bundle configuration commands


oam-bundle [manage] [frequency]oam-bundle [manage] [frequency]

Router(config-atm-vc)#

• Enables VC management with end-to-end OAM cells• Cells are sent, but the bundle is not managed if the manage

keyword is omitted• The frequency parameter specifies the cell generation rate in

seconds

Configuring OAM Management in the Bundle

Configuring OAM Management in the Bundle

oam retry up-count down-count retry-frequencyoam retry up-count down-count retry-frequencyRouter(config-atm-vc)#

• Specifies the OAM management-related thresholds• The up-count and down-count parameters specify the number of

consecutive cells that have to be received (or lost) before the VC is declared up or down

• The retry-frequency parameter specifies the cell send frequency during VC state change verification


bump implicitbump implicit


• Configures implicit bumping rules for the bundle or individual VC in the bundle

• If the VC fails, the traffic is bumped to the VC carrying lower-precedence traffic

Configuring Traffic BumpingConfiguring Traffic Bumping

bump explicit precedencebump explicit precedenceRouter(config-atm-vc)#

• Configures explicit bumping rules for the bundle or individual VC in the bundle

• If the VC fails, the traffic is bumped to the VC currently carrying packets with specified IP Precedence


no bump trafficno bump traffic


• Prevents the VC (or all VCs in a bundle) from accepting bumped traffic

Configuring Traffic BumpingConfiguring Traffic Bumping

bump trafficbump trafficRouter(config-atm-vc)#

• Allows the VC (or all VCs in a bundle) to accept bumped traffic


Configuring a VC-Wide VC ClassConfiguring a VC-Wide VC Class

class-vc vc-class-nameprecedence [other | range ]bump {implicit | explicit precedence-level | traffic}protect {group | vc }ubr | ubr+ | vbr-nrt atm-qos-parametersrandom-detect [attach group-name]

class-vc vc-class-nameprecedence [other | range ]bump {implicit | explicit precedence-level | traffic}protect {group | vc }ubr | ubr+ | vbr-nrt atm-qos-parametersrandom-detect [attach group-name]

Router(config)#

• Configures all parameters that can be specified on an ATM VC within the bundle in a VC class


Configuring an ATM VC in a Bundle

Configuring an ATM VC in a Bundle

bundle bundle-namepvc name [vpi/]vci

class vc-class-nameprecedence [other | range ]bump {implicit | explicit precedence-level | traffic}protect {group | vc}ubr | ubr+ | vbr-nrt atm-qos-parametersrandom-detect [attach group-name]

bundle bundle-namepvc name [vpi/]vci

class vc-class-nameprecedence [other | range ]bump {implicit | explicit precedence-level | traffic}protect {group | vc}ubr | ubr+ | vbr-nrt atm-qos-parametersrandom-detect [attach group-name]

Router(config-if)#

• Configures an individual VC in an ATM VC bundle• If a vc-class template is applied to the VC, the VC inherits

parameters specified in the vc-class template• Individual parameters specified in the vc-class template can

be overwritten by bundle configuration commands• Unspecified VC parameters are inherited from the bundle or

from the ATM interface


Map IP Precedence to an ATM VC

Map IP Precedence to an ATM VC

precedence [other | range ]precedence [other | range ]


• Maps packets with a specified range of IP Precedence into the configured ATM VC

• All the unmapped IP Precedence values are mapped to the VC specifying “other”

• Default: VC accepts all unspecified IP traffic


VC ProtectionVC Protection

protect { group | vc }protect { group | vc }


• Configures the VC to be part of a protected group or to be individually protected

• A bundle is declared down if all VCs in the protected group are lost or if any individually protected VC is lost

• Only one protected group can be configured in a bundle

• Default: VC is not protected


VC Inheritance RulesVC Inheritance Rules

• VC parameters are inherited in this order

–Parameters specified on the individual VC

–Parameters specified in the VC class applied to the individual VC

–Parameters specified on the bundle to which the VC belongs

–Parameters specified in the VC class applied to the bundle

–Parameters specified on an interface or subinterface


ATM VC Bundle Case Study

ATM VC Bundle Case Study

• IP traffic is transported across an international ATM PVC with these IP Precedence values:PrecedenceMeaning

0-1 Best-effort Internet traffic2-3 Premium Internet traffic

4 VPN traffic5 VoIP traffic

6-7 Routing protocols

• Voice, VPN, and premium Internet traffic shall be transported across dedicated PVCs for easier provisioning.


Case Study Step 1: Bundle Design

Case Study Step 1: Bundle Design

• Precedence 5 traffic (VoIP) is transported over a separate VC; no bumping is possible

• Precedence 2-3 traffic (premium Internet) is transported over a separate VC; can be bumped onto the best-effort VC

• Precedence 4 traffic (VPN) is transported over a separate VC; can be bumped onto best-effort VC

• Control traffic is transported over a separate VC; can be bumped onto the best-effort VC

• Best-effort VC can be bumped onto premium Internet VC

• WRED has to be deployed on all VCs to prevent bumped best-effort traffic from congesting the VC


Router ConfigurationRouter Configuration

Case Study Step 2: Configuring VC Classesvc-class best_effort vc-class vpn precedence other precedence 4 bump explicitly 2 bump explicitly 0 protect group protect group! !vc-class premium vc-class voip precedence 2-3 precedence 5 bump implicitly no bump traffic protect group protect vc! !vc-class bundle vc-class control encapsulation aal5snap precedence 6-7 broadcast bump explicitly 0 protocol ip inarp protect group oam-bundle manage 3

vc-class best_effort vc-class vpn precedence other precedence 4 bump explicitly 2 bump explicitly 0 protect group protect group! !vc-class premium vc-class voip precedence 2-3 precedence 5 bump implicitly no bump traffic protect group protect vc! !vc-class bundle vc-class control encapsulation aal5snap precedence 6-7 broadcast bump explicitly 0 protocol ip inarp protect group oam-bundle manage 3



Case Study Step 3: Configuring the WRED Profile Guaranteed_BW_PVC

random-detect-group guaranteed_bw_pvc precedence 0 20 40 10 precedence 1 25 40 10 precedence 2 35 40 10 precedence 6 30 40 10 precedence 7 30 40 10

random-detect-group guaranteed_bw_pvc precedence 0 20 40 10 precedence 1 25 40 10 precedence 2 35 40 10 precedence 6 30 40 10 precedence 7 30 40 10



Case Study Step 4: Configure the Bundle and Individual PVC

interface ATM 5/1/0.22 point-to-point ip address 216.23.45.5 255.255.255.252 bundle SanFrancisco class bundle pvc-bundle SF-control 26 class control vbr-nrt 1000 1000 pvc-bundle SF-voip 25 class voip vbr 2000 2000 pvc-bundle SF-vpn 24 class vpn vbr-nrt 4000 4000 pvc-bundle SF-guaranteed 22 class guaranteed_bw random-detect attach guaranteed_bw_pvc vbr-nrt 8000 8000 pvc-bundle SF-best-effort 23 class best_effort random-detect

interface ATM 5/1/0.22 point-to-point ip address 216.23.45.5 255.255.255.252 bundle SanFrancisco class bundle pvc-bundle SF-control 26 class control vbr-nrt 1000 1000 pvc-bundle SF-voip 25 class voip vbr 2000 2000 pvc-bundle SF-vpn 24 class vpn vbr-nrt 4000 4000 pvc-bundle SF-guaranteed 22 class guaranteed_bw random-detect attach guaranteed_bw_pvc vbr-nrt 8000 8000 pvc-bundle SF-best-effort 23 class best_effort random-detect


SummarySummary

Upon completing this lesson, you should be able to:• Describe VC bundling

• Configure VC bundling

• Monitor and troubleshoot VC bundling



1. How does VC bundling classify IP packets?

2. Which QoS mechanisms are used in conjunction with VC bundling?

3. How many parallel VCs can be used for one IP adjacency?

4. How many IP Precedence values can map into one VC?


Per-VC CB-WFQPer-VC CB-WFQ




Upon completing this lesson, you will be able to: • Describe per-VC CBWFQ

• Configure per-VC CBWFQ

• Monitor and troubleshoot per-VC CBWFQ


Per-VC CBWFQPer-VC CBWFQ

• Class-based weighted fair queuing (CBWFQ) can be used on ATM interfaces.

• QoS service policies can be applied to:

– An interface

– A subinterface

– An individual virtual circuit

• Supported service policies are:

– CBWFQ including WRED

– CBLLQ

– Class-based marking, including setting of ATM CLP bit

– Class-based shaping

– Class-based policing, including setting of ATM CLP bit


Per-Interface CBWFQPer-Interface CBWFQ

• CBWFQ can be applied to an entire interface.

Interface ATM1/0/0

SubinterfaceATM1/0/0.1


PVC 0/50

PVC 0/51

PVC 0/52

PVC 0/53

PVC 0/54

CBWFQCBWFQ

class-map HTTP match http!policy-map LimitHTTP class HTTP police 256000 conform transmit exceed set-clp-transmit!interface ATM5/0/0 service-policy output LimitHTTP!

class-map HTTP match http!policy-map LimitHTTP class HTTP police 256000 conform transmit exceed set-clp-transmit!interface ATM5/0/0 service-policy output LimitHTTP!


Per-Subinterface CBWFQPer-Subinterface CBWFQ

• CBWFQ can be applied to subinterfaces.

Interface ATM1/0/0



PVC 0/50

PVC 0/51

PVC 0/52

PVC 0/53

PVC 0/54

CBWFQCBWFQ

CBWFQCBWFQ

class-map CorporateTraffic interface ATM5/0/0.1 point-to-point match access-group 100 service-policy output Smart! pvc Core 0/51policy-map Smart vbr-nrt 10000 2000 class CorporateTraffic ! bandwidth 10000 class class-default set atm-clp!

class-map CorporateTraffic interface ATM5/0/0.1 point-to-point match access-group 100 service-policy output Smart! pvc Core 0/51policy-map Smart vbr-nrt 10000 2000 class CorporateTraffic ! bandwidth 10000 class class-default set atm-clp!


Per-Interface CBWFQPer-Interface CBWFQ

• CBWFQ can be applied to an individual virtual circuit.

Interface ATM1/0/0



PVC 0/50

PVC 0/51

PVC 0/52

PVC 0/53

PVC 0/54

CBWFQ

CBWFQ

CBWFQ

CBWFQ

CBWFQ


Per-Interface CBWFQConfiguration ExamplePer-Interface CBWFQ

Configuration Example

class-map MatchCorporate match access-group 100!policy-map MARK class MatchCorporate police 2000000 conform-action transmit exceed-action set-clp-transmit!interface ATM5/0/0 ip address 10.1.1.1 255.255.255.0 service-policy output MARK pvc 0/50 vbr-nrt 500 400 1000 inarp 1 broadcast!access-list 100 permit ip 10.0.0.0 0.255.255.255 10.0.0.0 0.255.255.255

class-map MatchCorporate match access-group 100!policy-map MARK class MatchCorporate police 2000000 conform-action transmit exceed-action set-clp-transmit!interface ATM5/0/0 ip address 10.1.1.1 255.255.255.0 service-policy output MARK pvc 0/50 vbr-nrt 500 400 1000 inarp 1 broadcast!access-list 100 permit ip 10.0.0.0 0.255.255.255 10.0.0.0 0.255.255.255


Per-VC CBWFQConfiguration Example

Per-VC CBWFQConfiguration Example

class-map MatchCorporate match access-group 100!policy-map MARK class MatchCorporate police 2000000 conform-action transmit exceed-action set-clp-transmit!interface ATM5/0/0 no ip address!interface ATM5/0/0.1 point-to-point ip address 10.1.1.1 255.255.255.0 pvc 0/50 vbr-nrt 500 400 1000 inarp 1 service-policy output MARK broadcast!access-list 100 permit ip 10.0.0.0 0.255.255.255 10.0.0.0 0.255.255.255

class-map MatchCorporate match access-group 100!policy-map MARK class MatchCorporate police 2000000 conform-action transmit exceed-action set-clp-transmit!interface ATM5/0/0 no ip address!interface ATM5/0/0.1 point-to-point ip address 10.1.1.1 255.255.255.0 pvc 0/50 vbr-nrt 500 400 1000 inarp 1 service-policy output MARK broadcast!access-list 100 permit ip 10.0.0.0 0.255.255.255 10.0.0.0 0.255.255.255


Monitoring and Troubleshooting Per-Interface CBWFQ

Monitoring and Troubleshooting Per-Interface CBWFQ

show policy-map interface ATM-interfaceshow policy-map interface ATM-interface

Router#

• Displays the service policy parameters and statistics for the selected interface or subinterfaceRouter#show policy interface atm 5/0/0.1

ATM5/0/0.1

Service-policy output: Smart (1755)

Class-map: CorporateTraffic (match-all) (1757/42) 0 packets, 0 bytes 5 minute offered rate 0 bps, drop rate 0 bps Match: access-group 100 (1761) queue size 0, queue limit 2500 packets output 0, packet drops 0 tail/random drops 0, no buffer drops 0, other drops 0 Bandwidth: kbps 10000, weight 29...

Router#show policy interface atm 5/0/0.1

ATM5/0/0.1

Service-policy output: Smart (1755)

Class-map: CorporateTraffic (match-all) (1757/42) 0 packets, 0 bytes 5 minute offered rate 0 bps, drop rate 0 bps Match: access-group 100 (1761) queue size 0, queue limit 2500 packets output 0, packet drops 0 tail/random drops 0, no buffer drops 0, other drops 0 Bandwidth: kbps 10000, weight 29...


Monitoring and Troubleshooting Per-VC CBWFQ

Monitoring and Troubleshooting Per-VC CBWFQ

show queueing interface ATM-interface [vc [VPI/]VCI]show queueing interface ATM-interface [vc [VPI/]VCI]

Router#

• Displays CBWFQ parameters and statistics for the selected interface, subinterface, or VC.Router#show queueing interface atm5/0Interface ATM5/0 VC 0/5 Queueing strategy: fifo Output queue 0/40, 0 drops per VC Interface ATM6/0 VC 0/16 Queueing strategy: fifo Output queue 0/40, 0 drops per VC Interface ATM6/0 VC 0/50 Queueing strategy: weighted fair Total output drops per VC: 0 Output queue: 0/512/64/0 (size/max total/threshold/drops) Conversations 0/1/32 (active/max active/max total) Reserved Conversations 0/0 (allocated/max allocated) Available Bandwidth 225 kilobits/sec

Router#show queueing interface atm5/0Interface ATM5/0 VC 0/5 Queueing strategy: fifo Output queue 0/40, 0 drops per VC Interface ATM6/0 VC 0/16 Queueing strategy: fifo Output queue 0/40, 0 drops per VC Interface ATM6/0 VC 0/50 Queueing strategy: weighted fair Total output drops per VC: 0 Output queue: 0/512/64/0 (size/max total/threshold/drops) Conversations 0/1/32 (active/max active/max total) Reserved Conversations 0/0 (allocated/max allocated) Available Bandwidth 225 kilobits/sec


SummarySummary

Upon completing this lesson, you should be able to:• Describe per-VC CBWFQ

• Configure per-VC CBWFQ

• Monitor and troubleshoot per-VC CBWFQ



1. Where can CBWFQ be attached on ATM interfaces?


RSVP to SVC MappingRSVP to SVC Mapping




Upon completing this lesson, you will be able to: • Describe RSVP-to-SVC mapping

• Configure RSVP-to-SVC mapping

• Monitor and troubleshoot RSVP-to-SVC mapping


RSVP-to-SVC MappingRSVP-to-SVC Mapping

• RSVP-enabled flows have bandwidth and delay requirements.

• Pass-through RSVP could hamper the quality of service if an ATM interface or PVC is congested.

• RSVP-enabled flows can get their own VCs and queues to prevent congestion from affecting these flows.

• RSVP reservations are mapped to SVCs.


RSVP-to-SVC Mapping (cont.)RSVP-to-SVC Mapping (cont.)

RSVPRSVP RSVPRSVP

SVC

• RSVP triggers SVC creation.

• ATM SVC parameters are calculated from the parameters in the RSVP reservation request.


ATM SVC ParametersATM SVC Parameters

SCR = BWRSVP . (53/48) . (MPS + DLE + UCO)/MPS

Data Link Encapsulation OverheadAAL5SNAP has 5 bytes of overhead.

Data Link Encapsulation OverheadAAL5SNAP has 5 bytes of overhead.

Minimum IP Packet SizeMinimum IP Packet Size

Unused Cell OverheadUnused Cell Overhead

Cell OverheadCell Overhead

Bandwidth Requested by RSVPBandwidth Requested by RSVP

Sustained Cell RateSustained Cell Rate

• Peak cell rate uses the same formula except it is based on the line rate or the configured peak cell rate.

Voice DataVoice DataIPHeader

IPHeader

AAL5SNAPHeader

AAL5SNAPHeader

ATMHeaderATM

HeaderATM

HeaderATM

Header Voice DataVoice Data UnusedUnused

Cell 1 Cell 2

5 5 43 5 48


RSVP-to-SVC MappingOptional QoS

RSVP-to-SVC MappingOptional QoS

• RSVP can mark conforming and exceeding packets with different IP Precedence or ToS values.

• Per-VC WRED can be used for differentiated dropping.


ConfiguringRSVP-to-SVC Mapping

ConfiguringRSVP-to-SVC Mapping

• These configuration steps are needed to enable RSVP-to-SVC mapping:

–Enable RSVP

–Enable SVC creation

–Optionally, enable RSVP-based marking and WRED

–Verify and monitor RSVP/ATM


Enabling RSVPEnabling RSVP

ip rsvp bandwidth reservable-bw max-flow-bwip rsvp bandwidth reservable-bw max-flow-bw

Router(config-if)#

• Enables RSVP reservation on an interface or subinterface

• The reservable-bw parameter specifies the total maximum amount of bandwidth that can be reserved by RSVP flows

• The max-flow-bw parameter specifies the maximum amount of bandwidth a that single flow can reserve


Enabling Creation of SVCsEnabling Creation of SVCs

ip rsvp svc-requiredip rsvp svc-required

Router(config-if)#

• Enables creation of SVC for RSVP reservation• ATM QoS parameters are determined by using the

parameters in the RSVP request

ip rsvp atm-peak-rate-limit limitip rsvp atm-peak-rate-limit limit

Router(config-if)#

• Sets the peak cell rate for all new SVCs• Uses the line rate as the default


RSVP-Based Marking and WREDRSVP-Based Marking and WRED

ip rsvp precedence {conform | exceed} precedenceip rsvp precedence {conform | exceed} precedence

Router(config-if)#

• Packets conforming to the reserved bandwidth are marked with conform precedence

• Packets exceeding the reserved bandwidth are marked with exceed precedence

• NetFlow has to be enabled

random-detect attach random-detect-grouprandom-detect attach random-detect-group

Router(config-if)#

• Enables per-VC WRED• Uses the WRED profiles specified in the WRED group random-detect-group

• CEF switching is required


RSVP-to-SVC MappingExample

RSVP-to-SVC MappingExample

interface ATM2/1/0 ip address 10.1.1.1 255.255.255.0 ip rsvp bandwidth 10000 10000 ip rsvp svc-required ip route-cache flow ip rsvp precedence conform 5 exceed 0 atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmi atm esi-address 111111111151.00 pvc pvc12 0/51 inarp 5 broadcast!

interface ATM2/1/0 ip address 10.1.1.1 255.255.255.0 ip rsvp bandwidth 10000 10000 ip rsvp svc-required ip route-cache flow ip rsvp precedence conform 5 exceed 0 atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmi atm esi-address 111111111151.00 pvc pvc12 0/51 inarp 5 broadcast!


Monitoring and Troubleshooting RSVP-to-SVC Mapping

Monitoring and Troubleshooting RSVP-to-SVC Mapping

show ip rsvp interface [intf]show ip rsvp interface [intf]

Router#

• Displays RSVP-related interface information

Router#show ip rsvp interfaceinterface allocated i/f max flow max pct UDP IP UDP_IP UDP M/CEt4/0 0M 7M 5M 0 0 0 0 0AT5/0/0 0M 10M 1M 0 0 0 0 0Se5/1/0 0M 192K 192K 0 0 0 0 0

Router#show ip rsvp interfaceinterface allocated i/f max flow max pct UDP IP UDP_IP UDP M/CEt4/0 0M 7M 5M 0 0 0 0 0AT5/0/0 0M 10M 1M 0 0 0 0 0Se5/1/0 0M 192K 192K 0 0 0 0 0


SummarySummary

Upon completing this lesson, you should be able to:• Describe RSVP-to-SVC mapping

• Configure RSVP-to-SVC mapping

• Monitor and troubleshoot RSVP-to-SVC mapping



1. How does RSVP benefit from using SVCs?

2. What are the necessary configuration steps to enable RSVP-to-SVC mapping?


Module SummaryModule Summary

Upon completing this module, you should be able to:• List the requirements of IP QoS in combination with ATM

QoS



• Describe and configure per-VC WRED

• Describe and configure VC bundling

• Describe and configure per-VC CBWFQ

• Describe RSVP-to-SVC mapping

• Monitor and troubleshoot IP QoS on ATM interfaces

© 2001, cisco systems, inc. ip over atm. © 2001, cisco systems, inc. qos v1.0—10-2 objectives...

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