Configuring IP to ATM Class of Service

This module describes the tasks for configuring the IP to ATM Class of Service (CoS), a feature suite that maps QoS characteristics between IP and ATM.

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IP to ATM CoS on a Single ATM VC Configuration Task List

To configure IP to ATM CoS for a single ATM virtual circuit (VC), perform the tasks described in the following sections. The tasks in the first two sections are required; the tasks in the remaining sections are optional.

The IP to ATM CoS feature requires ATM permanent virtual circuit (PVC) management.

Defining the WRED Parameter Group

Command

Purpose 


Router(config)# random-detect-group   group-name

Defines the WRED or VIP-distributed WRED (DWRED) parameter group.

Configuring the WRED Parameter Group

SUMMARY STEPS

  1. Device(config)# random-detect-group group-name
  2. Device(config)# exponential-weighting-constant exponent
  3. Device(config)# precedence precedence min-threshold max-threshold mark-probability-denominator

DETAILED STEPS

  Command or Action Purpose

Step 1

Device(config)# random-detect-group group-name

Specifies the WRED or DWRED parameter group.

Step 2

Device(config)# exponential-weighting-constant exponent

Configures the exponential weight factor for the average queue size calculation for the specified WRED or DWRED parameter group.

or

Step 3

Device(config)# precedence precedence min-threshold max-threshold mark-probability-denominator

Configures the specified WRED or DWRED parameter group for a particular IP precedence.

Displaying the WRED Parameters

Command

Purpose 


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

Displays the parameters of every VC with WRED or DWRED enabled on the specified ATM subinterface.

Displaying the Queueing Statistics

Command

Purpose 


Router# show queueing interface  interface-number  [vc  [[vpi /] vci ]]

Displays the queueing statistics of a specific VC on an interface.

IP to ATM CoS on an ATM Bundle Configuration Task List

To configure IP to ATM CoS on an ATM bundle, perform the tasks in the following sections.

The IP to ATM CoS feature requires ATM PVC management.

Creating a VC Bundle

Command

Purpose 


Router(config-subif)# bundle   bundle-name

Creates the specified bundle and enters bundle configuration mode.

Applying Bundle-Level Parameters

Configuring Bundle-Level Parameters

Command

Purpose 


Device(config-atm-bundle)# protocol  protocol  {protocol-address  | inarp } [[no ] broadcast ]

Configures a static map or enables Inverse Address Resolution Protocol (Inverse ARP) or Inverse ARP broadcasts for the bundle.

Note

 

Bundle-level parameters can be applied either by assigning VC classes or by directly applying them to the bundle. Parameters applied through a VC class assigned to the bundle are superseded by those applied at the bundle level. Bundle-level parameters are superseded by parameters applied to an individual VC. 


Device(config-atm-bundle)# encapsulation  aal-encap

Configures the ATM adaptation layer (AAL) and encapsulation type for the bundle. 


Device(config-atm-bundle)# inarp  minutes

Configures the Inverse ARP time period for all VC bundle members. 


Device(config-atm-bundle)# broadcast

Enables broadcast forwarding for all VC bundle members. 


Device(config-atm-bundle)# oam retry  up-count down-count retry frequency

Configures the VC bundle parameters related to operation, administration, and maintenance (OAM) management. 


Device(config-atm-bundle)# oam-bundle  [manage ] [frequency ]

Enables end-to-end F5 OAM loopback cell generation and OAM management for all VCs in the bundle.

Configuring VC Class Parameters to Apply to a Bundle

Command

Purpose 


Router(config-vc-class)# oam-bundle  [manage ] [frequency ]

Enables end-to-end F5 OAM loopback cell generation and OAM management for all VCs in the bundle.

Note

 

Use of a VC class allows you to configure a bundle applying multiple attributes to it at once because you apply the class itself to the bundle. Use of a class allows you to generalize a parameter across all VCs, after which (for some parameters) you can modify that parameter for individual VCs. (See the section "Applying Parameters to Individual VCs" for more information.)

Attaching a Class to a Bundle

Command

Purpose 


(config-atm-bundle)# class-bundle  vc-class-name

Configures a bundle with the bundle-level commands contained in the specified VC class.

Note

 

Parameters set through bundle-level commands contained in the VC class are applied to the bundle and all of its VC members. Bundle-level parameters applied through commands configured directly on the bundle supersede those applied through a VC class. Some bundle-level parameters applied through a VC class or directly to the bundle can be superseded by commands that you directly apply to individual VCs in bundle-vc configuration mode.

Committing a VC to a Bundle

Command

Purpose 


Device(config-atm-bundle)# pvc-bundle  pvc-name  [vpi /] [vci ]

Adds the specified VC to the bundle and enters bundle-vc configuration mode in order to configure the specified VC bundle member.

Applying Parameters to Individual VCs

Configuring a VC Bundle Member Directly

Command

Purpose 


Device(config-if-atm-member)# ubr  output-pcr  [input-pcr ]

Configures the VC for unspecified bit rate (UBR) QoS and specifies the output peak cell rate (PCR) for it. 


Device(config-if-atm-member)# ubr+   output-pcr output-mcr  [input-pcr ] [input-mcr ]

Configures the VC for UBR QoS and specifies the output PCR and output minimum guaranteed cell rate for it. 


Device(config-if-atm-member)# vbr-nrt   output-pcr output-scr  output-mbs  [input-pcr ] [input-scr ] [input-mbs ]

Configures the VC for variable bit rate nonreal-time (VBR-nrt) QoS and specifies the output PCR, output sustainable cell rate, and output maximum burst cell size for it. 


Device(config-if-atm-member)# precedence  [other  | range ]

Configures the precedence levels for the VC. 


Device(config-if-atm-member)# bump  {implicit  | explicit  precedence-level  | traffic }

Configures the bumping rules for the VC. 


Device(config-if-atm-member)# protect  {group  | vc }

Configures the VC to belong to the protected group of the bundle or to be an individually protected VC bundle member.

Configuring VC Class Parameters to Apply to a VC Bundle Member

Command

Purpose 


Device(config-vc-class)# bump  {implicit  | explicit  precedence-level  | traffic }

Specifies the bumping rules for the VC member to which the class is applied. These rules determine to which VC in the bundle traffic is directed when the carrier VC bundle member goes down.

Note

 

You can also add the following commands to a VC class to be used to configure a VC bundle member: ubr , ubr+ , and vbr-nrt . When a VC is a member of a VC bundle, the following commands cannot be used in vc-class mode to configure the VC: encapsulation , protocol , inarp , and broadcast . These commands are useful only at the bundle level, not the bundle member level. Configuration for an individual VC overrides the collective configuration applied to all VC bundle members through application of a VC class to the bundle. 


Device(config-vc-class)# precedence  precedence min-threshold max-threshold mark-probability-denominator

Defines precedence levels for the VC member to which the class is applied. 


Device(config-vc-class)# protect  {group  | vc }

Configures the VC as a member of the protected group of the bundle or as an individually protected VC.

Applying a VC Class to a Discrete VC Bundle Member

Command

Purpose 


Device(config-if-atm-member)# class-vc   vc-class -name

Assigns a VC class to a VC bundle member.

Configuring a VC Not to Accept Bumped Traffic

Command

Purpose 


Device(config-if-atm-member)# no bump traffic

Configures the VC not to accept any bumped traffic that would otherwise be redirected to it.

Monitoring and Maintaining VC Bundles and Their VC Members

Command

Purpose 


Device# show atm bundle   bundle-name

Displays the bundle attributes assigned to each bundle VC member and the current working status of the VC members. 


Device# show atm bundle  bundle-name   statistics  [detail ]

Displays statistics or detailed statistics on the specified bundle. 


Device# show atm map

Displays a list of all configured ATM static maps to remote hosts on an ATM network and on ATM bundle maps. 


Device# debug atm bundle errors

Displays information on bundle errors. 


Device# debug atm bundle events

Displays a record of bundle events.

Per-VC WFQ and CBWFQ Configuration Task List

To configure IP to ATM CoS for per-VC WFQ and CBWFQ, perform the tasks described in the following sections.

The IP to ATM CoS feature requires ATM PVC management.

Configuring Class-Based Weighted Fair Queueing

Before configuring CBWFQ for a VC, you must perform the following tasks using standard CBWFQ commands:

  • Create one or more classes to be used to classify traffic sent across the VC

  • Define a policy-map containing the classes to be used as the service policy


Note

You can configure class policies for as many classes as are defined on the router, up to the maximum of 64. However, the total amount of bandwidth allocated for all classes included in a policy-map to be attached to a VC must not exceed 75 percent of the available bandwidth of the VC. The remaining 25 percent of available bandwidth is used for encapsulation, such as the ATM cell overhead (also referred to as ATM cell tax), routing and best-effort traffic, and other functions that assume overhead. For more information on bandwidth allocation, see the "Congestion Management Overview" module.

Because CBWFQ gives you minimum bandwidth guarantee, you can only apply CBWFQ to VCs having these classes of service: available bit rate (ABR) and variable bit rate (VBR). You cannot apply per-VC WFQ and CBWFQ to UBR and unspecified bit rate plus (UBR+) VCs because both of these service classes are best-effort classes that do not guarantee minimum bandwidth. When CBWFQ is enabled for a VC, all classes configured as part of the service policy are installed in the fair queueing system.

In addition to configuring CBWFQ at the VC level, the IP to ATM CoS feature allows you to configure flow-based WFQ at the VC level. Because flow-based WFQ gives you best-effort class of service--that is, it does not guarantee minimum bandwidth--you can configure per-VC WFQ for all types of CoS VCs: ABR, VBR, UBR, and UBR+.

Per-VC WFQ uses the class-default class. Therefore, to configure per-VC WFQ, you must first create a policy-map and configure the class-default class. (You need not create the class-default class, which is predefined, but you must configure it.) For per-VC WFQ, the class-default class must be configured with the fair-queue policy-map class configuration command.

In addition to configuring the fair-queue policy-map class configuration command, you can configure the default class with either the queue-limit command or the random-detect command, but not both. Moreover, if you want the default class to use flow-based WFQ, you cannot configure the default class with the bandwidth policy-map class configuration command--to do so would disqualify the default class as flow-based WFQ, and therefore limit application of the service policy containing the class to ABR and VBR VCs.

Attaching a Service Policy and Enabling CBWFQ for a VC

Attaching a Policy-Map to a Standalone VC and Enabling CBWFQ

Command

Purpose 


Router(config-if-atm-vc)# service-policy output   policy-map

Enables CBWFQ and attaches the specified service policy-map to the VC being created or modified.

Attaching a Policy-Map to an Individual VC and Enabling CBWFQ

Command

Purpose 


Router(config-if-atm-member)# service-policy output   policy-map

Enables CBWFQ and attaches the specified service policy-map to the VC being created or modified.

Note

The service-policy output and random-detect-group commands are mutually exclusive; you cannot apply a WRED group to a VC for which you have enabled CBWFQ through application of a service policy. Moreover, before you can configure one command, you must disable the other if it is configured.

Configuring a VC to Use Flow-Based WFQ

SUMMARY STEPS

  1. Device(config)# policy-map policy-map
  2. Device(config-pmap)# class class-default default-class-name
  3. Device(config-pmap-c)# fair-queue number-of-dynamic-queues
  4. Do one of the following:
    • Device(config-pmap-c)# queue-limit number-of-packets
    • Device(config-pmap-c)# random-detect

DETAILED STEPS

  Command or Action Purpose

Step 1

Device(config)# policy-map policy-map

Specifies the name of the policy-map to be created or modified.

Step 2

Device(config-pmap)# class class-default default-class-name

Specifies the default class so that you can configure or modify its policy.

Note

 

You can include other classes in the same policy-map as the one that contains the flow-based WFQ class. Packets not otherwise matched are selected by the default class-default class match criteria.

Step 3

Device(config-pmap-c)# fair-queue number-of-dynamic-queues

Specifies the number of dynamic queues to be reserved for use by flow-based WFQ running on the default class.

Note

 

By default--that is, even if you do not configure the class-default class with the fair-queue policy-map class configuration command and you do not configure it with the bandwidth policy-map class configuration command--the default class is defined as flow-based WFQ.

Step 4

Do one of the following:

  • Device(config-pmap-c)# queue-limit number-of-packets
  • Device(config-pmap-c)# random-detect

Specifies the maximum number of packets that can be queued for the class.

Enables WRED. The class policy will drop packets using WRED instead of tail drop.

Attaching a Policy-Map to a Standalone VC and Enabling WFQ

Command

Purpose 


Device(config-if-atm-vc)# service-policy output   policy-map

Enables WFQ for the VC by attaching the specified policy-map containing the class-default class to the VC being created or modified.

Attaching a Policy-Map to an Individual VC and Enabling WFQ

Command

Purpose 


Device(config-if-atm-member)# service-policy output   policy-map

Enables WFQ for the VC bundle member by attaching the specified policy-map containing the class-default class to the VC bundle member.

Monitoring per-VC WFQ and CBWFQ

Command

Purpose 


Device# show policy-map  interface interface-number  [vc  [vpi/ ] vci ]]

Displays the contents of packets inside a queue for a particular interface or VC.

Enabling Logging of Error Messages to the Console

Command

Purpose 


Router(config)# logging console   level

Limits messages logged to the console based on severity.

IP to ATM CoS Configuration Examples

Example Single ATM VC with WRED Group and IP Precedence

The following example creates a PVC on an ATM interface and applies the WRED parameter group called sanjose to that PVC. Next, the IP Precedence values are configured for the WRED parameter group sanjose. 


interface ATM1/1/0.46 multipoint
 ip address 200.126.186.2 255.255.255.0
 no ip mroute-cache
 shutdown
pvc 46 
 encapsulation aal5nlpid 
 random-detect attach sanjose
!
random-detect-group sanjose
 precedence 0  200   1000 10 
 precedence 1  300   1000 10 
 precedence 2  400   1000 10 
 precedence 3  500   1000 10 
 precedence 4  600   1000 10 
 precedence 5  700   1000 10 
 precedence 6  800   1000 10 
 precedence 7  900   1000 10

Example VC Bundle Configuration Using a VC Class

This example configures VC bundle management on a router that uses Intermediate System-to-Intermediate System (IS-IS) as its IP routing protocol.

Bundle-Class Class

At the outset, this configuration defines a VC class called bundle-class that includes commands that set VC parameters. When the class bundle-class is applied at the bundle level, these parameters are applied to all VCs that belong to the bundle. Note that any commands applied directly to an individual VC of a bundle in bundle-vc mode take precedence over commands applied globally at the bundle level. Taking into account hierarchy precedence rules, VCs belonging to any bundle to which the class bundle-class is applied will be characterized by these parameters: aal5snap encapsulation, broadcast on, use of Inverse Address Resolution Protocol (ARP) to resolve IP addresses, and operation, administration, and maintenance (OAM) enabled. 


router isis
 net 49.0000.0000.0000.1111.00
vc-class atm bundle-class
 encapsulation aal5snap
 broadcast
 protocol ip inarp
 oam-bundle manage 3
 oam retry 4 3 10

The following sections of the configuration define VC classes that contain commands specifying parameters that can be applied to individual VCs in a bundle by assigning the class to that VC.

Control-Class Class

When the class called control-class is applied to a VC, the VC carries traffic whose IP Precedence level is 7. When the VC to which this class is assigned goes down, it takes the bundle down with it because this class makes the VC a protected one. The QoS type of a VC using this class is vbr-nrt. 


vc-class atm control-class
 precedence 7
 protect vc
 vbr-nrt 10000 5000 32

Premium-Class Class

When the class called premium-class is applied to a VC, the VC carries traffic whose IP Precedence levels are 6 and 5. The VC does not allow other traffic to be bumped onto it. When the VC to which this class is applied goes down, its bumped traffic will be redirected to a VC whose IP Precedence level is 7. This class makes a VC a member of the protected group of the bundle. When all members of a protected group go down, the bundle goes down. The QoS type of a VC using this class is vbr-nrt. 


vc-class atm premium-class
 precedence 6-5
 no bump traffic
 protect group
 bump explicitly 7
 vbr-nrt 20000 10000 32

Priority-Class Class

When the class called priority-class is applied to a VC, the VC is configured to carry traffic with IP Precedence in the 4-2 range. The VC uses the implicit bumping rule, it allows traffic to be bumped, and it belongs to the protected group of the bundle. The QoS type of a VC using this class is ubr+. 


vc-class atm priority-class
 precedence 4-2
 protect group
 ubr+ 10000 3000

Basic-Class Class

When the class called basic-class is applied to a VC, the VC is configured through the precedence other command to carry traffic with IP Precedence levels not specified in the profile. The VC using this class belongs to the protected group of the bundle. The QoS type of a VC using this class is ubr. 


vc-class atm basic-class
 precedence other
 protect group
 ubr 10000

The following sets of commands configure three bundles that the router subinterface uses to connect to three of its neighbors. These bundles are called new-york, san-francisco, and los-angeles. Bundle new-york has four VC members, bundle san-francisco has four VC members, and bundle los-angeles has three VC members.

new-york Bundle

The first part of this example specifies the IP address of the subinterface, the router protocol--the router uses IS-IS as an IP routing protocol--and it creates the first bundle called new-york and enters bundle configuration mode: 


interface atm 1/0.1 multipoint
 ip address 10.0.0.1 255.255.255.0
 ip router isis
 bundle new-york

From within bundle configuration mode, the next portion of the configuration uses two protocol commands to enable IP and Open Systems Interconnect (OSI) traffic flows in the bundle. The OSI routing packets will use the highest precedence VC in the bundle. The OSI data packets, if any, will use the lowest precedence VC in the bundle. If configured, other protocols, such as IPX or AppleTalk, will always use the lowest precedence VC in the bundle.

As the indentation levels of the preceding and following commands suggest, subordinate to bundle new-york is a command that configures its protocol and a command that applies the class called bundle-class to it. 


  protocol ip 1.1.1.2 broadcast
  protocol clns 49.0000.0000.2222.00 broadcast
  class-bundle bundle-class

The class called bundle-class, which is applied to the bundle new-york, includes a protocol ip inarp command. According to inheritance rules, protocol ip , configured at the bundle level, takes precedence over protocol ip inarp specified in the class bundle-class.

The next set of commands beginning with pvc-bundle ny-control 207 , which are further subordinate, add four VCs (called ny-control, ny-premium, ny-priority, and ny-basic) to the bundle new-york. A particular class--that is, one of the classes predefined in this configuration example--is applied to each VC to configure it with parameters specified by commands included in the class.

As is the case for this configuration, to configure individual VCs belonging to a bundle, the router must be in bundle mode for the mother bundle. For each VC belonging to the bundle, the subordinate mode is pvc-mode for the specific VC.

The following commands configure the individual VCs for the bundle new-york: 


  pvc-bundle ny-control 207
   class-vc control-class
  pvc-bundle ny-premium 206
   class-vc premium-class
  pvc-bundle ny-priority 204
   class-vc priority-class
  pvc-bundle ny-basic 201
   class-vc basic-class

san-francisco Bundle

The following set of commands create and configure a bundle called san-francisco. At the bundle configuration level, the configuration commands included in the class bundle-class are ascribed to the bundle san-francisco and to the individual VCs that belong to the bundle. Then, the pvc-bundle command is executed for each individual VC to add it to the bundle. After a VC is added and bundle-vc configuration mode is entered, a particular, preconfigured class is assigned to the VC. The configuration commands comprising that class are used to configure the VC. Rules of hierarchy apply at this point. Command parameters contained in the applied class are superseded by the same parameters applied at the bundle configuration level, which are superseded by the same parameters applied directly to a VC. 


 bundle san-francisco
  protocol clns 49.0000.0000.0000.333.00 broadcast
  inarp 1
  class-bundle bundle-class
  pvc-bundle sf-control 307
   class-vc control-class
  pvc-bundle sf-premium 306
   class-vc premium-class
  pvc-bundle sf-priority 304
   class-vc priority-class
  pvc-bundle sf-basic 301
   class-vc basic-class

los-angeles Bundle

The following set of commands create and configure a bundle called los-angeles. At the bundle configuration level, the configuration commands included in the class bundle-class are ascribed to the bundle los-angeles and to the individual VCs that belong to the bundle. Then, the pvc-bundle command is executed for each individual VC to add it to the bundle. After a VC is added and bundle-vc configuration mode is entered, precedence is set for the VC and the VC is either configured as a member of a protected group (protect group) or as an individually protected VC. A particular class is then assigned to each VC to further characterize it. Rules of hierarchy apply. Parameters of commands applied directly and discretely to a VC take precedence over the same parameters applied within a class to the VC at the bundle-vc configuration level, which take precedence over the same parameters applied to the entire bundle at the bundle configuration level. 


 bundle los-angeles
  protocol ip 1.1.1.4 broadcast
  protocol clns 49.0000.0000.4444.00 broadcast
  inarp 1
  class-bundle bundle-class
  pvc-bundle la-high 407
   precedence 7-5
   protect vc
   class-vc premium-class
  pvc-bundle la-mid 404
   precedence 4-2
   protect group
   class-vc priority-class
  pvc-bundle la-low 401
   precedence other
   protect group
   class-vc basic-class

Example Per-VC WFQ and CBWFQ on a Standalone VC

The following example creates two class maps and defines their match criteria. For the first map class, called class1, the numbered access control list (ACL) 101 is used as the match criterion. For the second map class called class2, the numbered ACL 102 is used as the match criterion.

Next, the example includes these classes in a policy-map called policy1. For class1, the policy includes a minimum bandwidth allocation request of 500 kbps and maximum packet count limit of 30 for the queue reserved for the class. For class2, the policy specifies only the minimum bandwidth allocation request of 1000 kbps, so the default queue limit of 64 packets is assumed. Note that the sum of the bandwidth requests for the two classes comprising policy1 is 75 percent of the total amount of bandwidth (2000 kbps) for the PVC called cisco to which the policy-map is attached.

The example attaches the policy-map called policy1 to a PVC. Once the policy-map policy1 is attached to the PVC, its classes constitute the CBWFQ service policy for that PVC. Packets sent on this PVC will be checked for matching criteria against ACLs 101 and 102 and classified accordingly.

Because the class-default command is not explicitly configured for this policy-map, all traffic that does not meet the match criteria of the two classes comprising the service policy is handled by the predefined class-default class, which provides best-effort flow-based WFQ. 


class-map class1
 match access-group 101
class-map class2
 match access-group 102
policy-map policy1
 class class1
  bandwidth 500
  queue-limit 30
 class class2
  bandwidth 1000 
interface ATM1/1/0.46 multipoint
 ip address 200.126.186.2 255.255.255.0
 pvc 46
  vbr-nrt 2000 2000
  encap aal5snap
  service policy output policy1

Example Per-VC WFQ and CBWFQ on Bundle-Member VCs

The following example shows a PVC bundle called san-francisco with members for which per-VC WFQ and CBWFQ are enabled and service policies configured. The example assumes that the classes included in the following policy-maps have been defined and that the policy-maps have been created: policy1, policy2, and policy4. For each PVC, the IP to ATM CoS pvc-bundle command is used to specify the PVC to which the specified policy-map is to be attached.

Note that PVC 0/34 and 0/31 have the same policy-map attached to them, policy2. Although you can assign the same policy-map to multiple VCs, each VC can have only one policy-map attached at an output PVC. 


bundle san-francisco
 protocol ip 1.0.2.20 broadcast
 encapsulation aal5snap
 pvc-bundle 0/35
  service policy output policy1
  vbr-nrt 5000 3000 500
  precedence 4-7
 pvc-bundle 0/34
  service policy output policy2
  vbr-nrt 5000 3000 500
  precedence 2-3
 pvc-bundle 0/33
  vbr-nrt 4000 3000 500
  precedence 2-3
  service policy output policy4
 pvc-bundle 0/31
  service policy output policy2