Table Of Contents

Configuring Quality of Service for PVC Bundles

PVC Bundles

Feature History for PVC Bundles

System Limits for PVC Bundles

Traffic Bumping

PVC Bundle Protection Rules

ATM PVC Selection

Feature History for ATM PVC Selection

Configuration Commands for ATM PVC Selection

bump Command

bundle Command

class-bundle Command

class-vc Command

mpls experimental Command

oam-bundle Command

precedence Command

protect Command

pvc-bundle Command

ATM Bundle Management

Bumping and ATM PVC Bundles

Prerequisites for ATM PVC Selection

Restrictions and Limitations for ATM PVC Selection

Configuring ATM Bundles

Creating an ATM Bundle Directly

Creating an ATM Bundle Using a VC Class

Adding an ATM PVC to a PVC Bundle

Configuring ATM Bundle Members

Configuring an ATM Bundle Member

Configuring an ATM Bundle Member Using a VC Class

Configuring a PVC Not to Accept Bumped Traffic

Verifying and Monitoring ATM PVC Bundles

Configuration Examples for Configuring ATM Bundles and PVC Selection

Configuration Example for ATM Bundle Configuration Using VC Classes

Configuration Example for MPLS EXP-Based ATM PVC Selection

Frame Relay PVC Selection

Feature History for Frame Relay PVC Selection

Configuration Commands for Frame Relay PVC Selection

bump Command (Frame Relay VC-bundle-member)

dscp Command (Frame Relay VC-bundle-member)

exp Command

frame-relay vc-bundle Command

precedence Command (Frame Relay VC-bundle-member)

protect Command (Frame Relay VC-bundle-member)

pvc Command (Frame Relay VC-bundle)

Service Levels and PVC Selection Criteria

Prerequisites for Frame Relay PVC Selection

Restrictions and Limitations for Frame Relay PVC Selection

Configuring Frame Relay Bundles

Creating a Frame Relay PVC Bundle

Adding a PVC to a Frame Relay PVC Bundle

Configuring Frame Relay Bundle Members

Configuration Examples for Configuring Frame Relay Bundles and PVC Selection

Configuration Example for Precedence-Based and DSCP-Based Frame Relay PVC Selection

Configuration Example for MPLS EXP-Based Frame Relay PVC Selection

Verifying and Monitoring Frame Relay PVC Selection

Verification Example for Monitoring PVC Bundles

Related Documentation

Configuring Quality of Service for PVC Bundles

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Networks can span many geographical locations and can utilize the full spectrum of networking technologies available for both network access and the network core. In some networks the core connections are over existing low-speed Frame Relay or ATM networks. Because service providers have invested substantially in these networks, providers need a way to differentiate themselves from other providers and increase profitability while using these low-speed links. The Cisco 10000 series router offers advanced IP QoS as a solution.

The Cisco 10000 series router provides IP QoS over multiple ATM and Frame Relay PVCs combined into PVC bundles. By using PVC bundles and QoS-based PVC selection to carry packets, service providers can increase bandwidth between two routers when the connectivity is limited to low-speed switched circuits.

This chapter describes PVC bundles and QoS-based PVC selection over ATM and Frame Relay PVCs. It includes the following topics:

•PVC Bundles

•ATM PVC Selection

•Frame Relay PVC Selection

•Related Documentation

PVC Bundles

A PVC bundle is a group of permanent virtual circuits (PVCs) combined into a logical group with a single, virtual interface that connects to a peer system. PVC bundles enable service providers to offer different levels of service through the use of IP precedence, differentiated services code point (DSCP), and Multiprotocol Label Switching (MPLS) experimental (EXP) levels, and QoS features. Using the PVC bundle management software, you can create a bundle of PVCs between a pair of connected routers and assign different QoS characteristics to individual PVCs in the bundle. Each PVC in a bundle has its own traffic class and traffic parameters, and is configured to carry packets whose priority matches the configured range.

Using PVC bundles, you can do the following:

•Create differentiated service by distributing IP precedence, DSCP, or MPLS EXP levels over different PVCs in the bundle.

•Map a single precedence, DSCP, or MPLS EXP level or a range of levels to each discrete PVC in the bundle, thereby enabling individual PVCs in the bundle to carry packets marked with different levels.

•Use Weighted Random Early Detection (WRED) to further differentiate service across traffic that has different precedence, DSCP, or MPLS EXP levels.

To determine which PVC in the bundle to use to forward an IP or MPLS packet, the router examines the packet's priority bits or Type of Service (ToS) field, or the packet's EXP bits. Each PVC in the bundle is configured to carry packets whose priority matches the configured precedence, DSCP, or MPLS EXP level. Combined with a queuing mechanism at the output interface, this offers a complete QoS solution for both data and voice, and allows for further granularization of data types to differentiate data priorities.

The router supports both ATM and Frame Relay PVC bundles.

Figure 19-1 shows a PVC bundle.

Figure 19-1 PVC Bundle

Feature History for PVC Bundles

Cisco IOS Release	Description	Required PRE
Release 12.0(26)S	PVC bundles over ATM and Frame Relay were introduced on the PRE1 and included support for IP precedence and DSCP-based PVC selection. The ATM PVC Bundle Enhancement—MPLS EXP-Based PVC Selection feature and the Frame Relay PVC Bundles with QoS Support for IP and MPLS feature were also introduced.	PRE1

System Limits for PVC Bundles

Table 19-1 lists the system limits for PVC bundles.

Table 19-1 System Limits for PVC Bundles

Bundle Type	Max. No. of Members Per Bundle	Max. No. of Bundles Per System
ATM	8	16,000
Frame Relay	8	16,000

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Note IP precedence and MPLS EXP have eight levels that you can assign and DSCP has 64 levels. To include all DSCP values, you can assign a range of DSCP values (for example, 9-16) to a particular DLCI and assign the remaining DSCP values to another DLCI using the dscp other command.

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Traffic Bumping

Traffic bumping provides a way to keep a PVC bundle up and traffic flowing even though some individual PVCs might be down. You can configure each PVC bundle member to bump traffic to another PVC in the bundle when the bundle member does down. You can also specify that a particular PVC can never accept bumped traffic from another PVC. The default is to accept bumped traffic.

You can specify traffic bumping as either implicit or explicit bumping. Implicit bumping diverts the traffic from a failed PVC to the PVC having the next lower service level. Explicit bumping forces the traffic to a specific PVC rather than allowing it to find a PVC carrying traffic of the next lower service level. The default is to perform implicit traffic bumping.

For example, consider a sample configuration with two PVCs: PVC1 and PVC2. You configure PVC1 to carry precedence level 3 traffic, PVC2 to accept bumped traffic and to carry precedence level 6 traffic, and PVC1 to bump its traffic to PVC2. If PVC1 goes down, the following occurs:

•PVC2 takes over.

•If PVC2 is already down or goes down later, the router selects an alternate PVC based on the bumping rule for PVC2.

•If the router cannot find an alternate PVC for the bumped traffic, the entire PVC bundle goes down.

If a bundle member allows PVC bumping, the router selects the next lower precedence level PVC when a PVC goes down. You can specify only one precedence level for bumping. If the PVC that carries the bumped traffic fails, the router applies the bumping rules specified for the failed PVC to the traffic. When the original PVC is up again, the router restores traffic to the original PVC.

PVC Bundle Protection Rules

PVC bundle protection rules provide a way to force the PVC bundle down even though some individual PVCs are up and might be able to handle all of the traffic, though perhaps not in a satisfactory manner. The protection rules add flexibility for controlling the state of the PVC bundle.

You can configure a PVC bundle member as an individually protected PVC or as part of a PVC bundle protected group. Only one protected group can exist within a PVC bundle; however, many individually protected PVCs can exist.

When a bundle goes down, the router cannot forward traffic using the bundle, even if some of the PVCs in the bundle are still up. The entire bundle goes down when:

•One individually protected PVC goes down

•All of the PVCs in a protected group go down.

If you do not specify a protection rule, the PVC bundle goes down only when all of the PVCs go down. However, if a PVC that has no place to bump its traffic goes down, the router brings down the entire bundle despite any protection rules that have been set up.

ATM PVC Selection

The Cisco 10000 series router can forward packets to ATM bundle members based on the IP precedence level or Multiprotocol Label Switching (MPLS) experimental (EXP) level of the packets.

The ATM PVC Bundle Enhancement—MPLS EXP-Based PVC Selection feature allows you to configure multiple PVCs with different QoS characteristics between any pair of ATM-connected routers and to configure a group of ATM PVCs with a single next-hop address. Packets are mapped to specific PVCs in the bundle on the basis of the precedence value or MPLS EXP value in the type of service (ToS) field of the IP header. Each packet is treated differently according to the QoS configured for each PVC.

The MPLS EXP-Based PVC Selection feature provides flexible PVC management within a PVC bundle by allowing traffic assigned to a failed PVC to be redirected to an alternate PVC within the bundle. It also allows you to configure the bundle to go down when certain PVCs go down. IP packets carrying different types of traffic can be transported on different PVCs within the same PVC bundle.

Using MPLS-based ATM PVC selection, you can do the following:

•Map a single precedence level or MPLS EXP level, or a range of precedence or MPLS EXP levels, to each PVC in the bundle. This enables you to limit an individual PVC to carry only packets marked with a specific precedence or MPLS EXP level, or packets marked with different precedence or MPLS EXP levels. For unlabeled packets that do not specify a selection criteria, the router uses IP precedence level as the default selection criteria for packet forwarding.

•Configure a PVC to support unmapped traffic. If the PVC fails, the router attempts to identify an alternate PVC. If the router cannot locate an alternate PVC, the router stops the PVC bundle.

•Create differentiated service using PVC bundles by distributing MPLS EXP levels over the different PVC bundle members.

•Use Weighted Random Early Detection (WRED) to further differentiate service across traffic that has different MPLS EXP levels.

The Cisco 10000 series router forwards non-IP packets using the PVC that is responsible for carrying precedence level 6 traffic. The router uses process-switching to forward locally generated packets as follows:

1. To determine which PVC in a bundle is used to forward a specific type of traffic, the ATM VC bundle management software matches MPLS EXP levels between packets and PVCs. Because all PVCs in a bundle share the same destination, the router forwards IP traffic to the next hop address for the bundle, but the PVC used to carry a packet depends on the value set for that packet in the MPLS EXP level of the type of service (ToS) byte of its header.

2. The ATM PVC bundle management software matches the MPLS EXP level of the packet to the MPLS EXP levels assigned to a PVC and sends the packet out on the appropriate PVC. The ATM PVC bundle management software also allows you to configure how traffic is redirected if a PVC goes down.

3. MPLS EXP-based PVC selection maps the IP precedence level in the IPv4 header to a PVC configured with the same value. The three precedence bits in the type of service (ToS) byte of the IP header defines the precedence levels for IP traffic. You can use a default PVC for all unspecified precedence levels.

4. After you define an ATM bundle and add PVCs to it, you can configure attributes and characteristics to discrete PVC bundle members, or you can apply them collectively at the bundle level. You can apply ATM traffic shaping to each PVC within a bundle.

Feature History for ATM PVC Selection

Cisco IOS Release	Description	Required PRE
Release 12.0(26)S	The ATM PVC Bundle Enhancement—MPLS EXP-Based PVC Selection feature was introduced on the PRE1.	PRE1

Configuration Commands for ATM PVC Selection

This section describes the following configuration commands:

•bump Command

•bundle Command

•class-bundle Command

•class-vc Command

•mpls experimental Command

•oam-bundle Command

•precedence Command

•protect Command

•pvc-bundle Command

bump Command

To configure the bumping rules for a PVC bundle or a specific PVC bundle member, use the bump command in VC class or bundle member configuration mode. To remove the explicit bumping rules and return to the default condition of implicit bumping, use the no form of the command.

bump {explicit precedence-level | implicit | traffic}

no bump {explicit precedence-level | implicit | traffic} 

Syntax Description

explicit precedence-level	Specifies the precedence level to which traffic on a VC or PVC is bumped when the VC or PVC goes down. Valid values are from 0 to 7.
implicit	Applies the implicit bumping rule, which is the default, to a single VC or PVC bundle member, or to all VCs in the bundle (VC-class mode). The implicit bumping rule stipulates that bumped traffic is to be carried by a VC or PVC with a lower precedence level.
traffic	Specifies that the VC or PVC accepts bumped traffic. By default, a PVC permits bumping and accepts bumped traffic. To configure a PVC to reject bumped traffic from another bundle member, enter the no bump traffic command.

bump Command History

Cisco IOS Release	Description
Release 12.0(26)S	This command was introduced on the PRE1.

Defaults

Implicit bumping

Permit bumping (VCs accept bumped traffic)

Configuration Mode

VC-class configuration (for a VC class)

Bundle-vc configuration (for an ATM VC bundle member)

Usage Guidelines for the bump Command

If you configure implicit bumping, bumped traffic is sent to the PVC configured to handle the next lower precedence level. When the original PVC that bumped the traffic comes back up, the traffic that it is configured to carry is restored to it. If no other positive forms of the bump command are configured, the bump implicit command takes effect.

If you configure a PVC with the bump explicit command, you can specify the precedence level or MPLS EXP level to which traffic is bumped when that PVC goes down, and the traffic is directed to a PVC mapped with that precedence or MPLS EXP level. If the PVC that picks up and carries the traffic goes down, the traffic is subject to the bumping rules for that PVC. You can specify only one precedence level for bumping.

The PVC accepts bumped traffic by default. If the PVC has been previously configured to reject bumped traffic, you must use the bump traffic command to return the PVC to its default condition.

To configure a discrete PVC to reject bumped traffic when the traffic is directed to it, use the no bump traffic command.

bundle Command

To create a bundle or modify an existing bundle, use the bundle command in subinterface configuration mode. To remove the specified bundle, use the no form of the command. By default, no bundle is specified.

bundle bundle-name

no bundle bundle-name 

Syntax Description

bundle-name

Specifies the name of the bundle to create or modify. The bundle-name is limited to 16 alphanumeric characters.

bundle Command History

Cisco IOS Release	Description
Release 12.0(26)S	This command was introduced on the PRE1.

Usage Guidelines for the bundle Command

In the bundle configuration mode you can configure the characteristics and attributes of the bundle and its members, such as the encapsulation type for all virtual circuits (VCs) in the bundle, the bundle management parameters, the service type, and so on. Attributes and parameters you configure in bundle configuration mode are applied to all bundle members.

VCs in a VC bundle are subject to the following configuration inheritance guidelines (listed in order of next highest precedence):

•VC configuration in bundle-vc mode

•Bundle configuration in bundle mode

•Subinterface configuration in subinterface mode

To display the status of bundles, use the show atm bundle and show atm bundle statistics commands.

class-bundle Command

To configure a virtual circuit (VC) bundle with the bundle-level commands contained in the specified VC class, use the class-bundle command in bundle configuration mode. To remove the VC class parameters from a VC bundle, use the no form of the command.

class-bundle vc-class-name

no class-bundle vc-class-name 

Syntax Description

vc-class-name

Name of the VC class that you are assigning to your VC bundle.

class-bundle Command History

Cisco IOS Release	Description
Release 12.0(26)S	This command was introduced on the PRE1.

Defaults

No VC class is assigned to the VC bundle.

Usage Guidelines for the class-bundle Command

To use this command, you must first enter the bundle command to create the bundle and enter bundle configuration mode.

Use this command to assign a previously defined set of parameters (defined in a VC class) to an ATM VC bundle. Parameters set through bundle-level commands that are contained in a VC class are applied to the bundle and its VC members.

You can add the following commands to a VC class to be used to configure a VC bundle: broadcast, encapsulation, inarp, oam-bundle, oam retry, and protocol.

Bundle-level parameters applied through commands that are configured directly on a bundle supersede bundle-level parameters applied through a VC class by the class-bundle command. 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.

class-vc Command

To assign a virtual circuit (VC) class to an ATM permanent virtual circuit (PVC) or PVC bundle member, use the class-vc command in the appropriate configuration mode. To remove a VC class, use the no form of this command.

class-vc vc-class-name

no class-vc vc-class-name 

Syntax Description

vc-class-name

Name of the VC class you are assigning to your ATM PVC, SVC, or VC bundle member.

class-vc Command History

Cisco IOS Release	Description
Release 12.0(26)S	This command was introduced on the PRE1.

Configuration Modes

Interface-ATM-VC configuration (for ATM PVCs)

Bundle-vc configuration (for VC bundle members)

PVC-range configuration (for PVC ranges)

Usage Guidelines for the class-vc Command

To use this command for assigning a VC class to a VC bundle member, you must first use the pvc-bundle command to enter bundle-vc configuration mode.

When you create a VC class for a VC bundle member, you can use the following commands to define your parameters: bump, precedence, protect, ubr, ubr+, and vbr-nrt. You cannot use the following commands in vc-class configuration mode to configure a VC bundle member: encapsulation, protocol, inarp, and broadcast. These commands are useful only at the bundle level, not the bundle member level.

Parameters applied to an individual VC supersede bundle-level parameters. Parameters that are directly configured for a VC through discrete commands entered in bundle-vc configuration mode supersede VC class parameters assigned to a VC bundle member by the class-vc command.

mpls experimental Command

To configure Multiprotocol Label Switching (MPLS) experimental (EXP) levels for a virtual circuit (VC) class that can be assigned to a PVC bundle and thus applied to all PVC members of that bundle, use the mpls experimental command in vc-class configuration mode. To remove the MPLS EXP levels from the VC class, use the no form of the command.

To configure the MPLS EXP levels for a PVC member of a bundle, use the mpls experimental command in bundle-vc configuration mode. To remove the MPLS EXP levels from the PVC, use the no form of the command.

mpls experimental [other | range]

no mpls experimental 

Syntax Description

other	(Optional) Any MPLS EXP levels that are not explicitly configured.
range	(Optional) A single MPLS EXP level specified as a number from 0 to 7, or a range of levels specified as a hyphenated range.

mpls experimental Command History

Cisco IOS Release	Description
Release 12.0(26)S	This command was introduced on the PRE1.

Defaults

Defaults to other, that is, any MPLS EXP levels that are not explicitly configured.

Configuration Modes

VC-class configuration (for a VC class)

Bundle-vc configuration (for ATM VC bundle members)

Usage Guidelines for the mpls experimental Command

Assignment of MPLS EXP levels to VC bundle members allows you to create differentiated service because you can distribute the MPLS EXP levels over the different VC bundle members. You can map a single level or a range of levels to each discrete VC in the bundle, thereby enabling VCs in the bundle to carry packets marked with different levels. Alternatively, you can configure a VC with the mpls experimental other command to indicate that it can carry traffic marked with levels not specifically configured for it. Only one VC in the bundle can be configured with the mpls experimental other command to carry all levels not specified. This VC is considered the default VC.

To use this command in vc-class configuration mode, enter the vc-class atm global configuration command before you enter this command. This command has no effect if the VC class that contains the command is attached to a standalone VC, that is, if the VC is not a bundle member.

To use this command to configure an individual bundle member in bundle-vc configuration mode, first enter the bundle command to enact bundle configuration mode for the bundle to which you want to add or modify the VC member to be configured. Then, use the pvc-bundle command to specify the VC to be created or modified and enter bundle-vc configuration mode.

VCs in a VC bundle are subject to the following configuration inheritance guidelines (listed in order of next highest MPLS EXP level):

•VC configuration in bundle-vc mode

•Bundle configuration in bundle mode (with the effect of assigned vc-class configuration)

•Subinterface configuration in subinterface mode

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Note If you are using an ATM interface, you must configure all MPLS EXP levels (ranging from 0 to 7) for the bundle. To do this, we recommend configuring one member of the bundle with the mpls experimental other command. The other keyword defaults to any MPLS EXP levels in the range from 0 to 7 that are not explicitly configured.

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oam-bundle Command

To enable end-to-end F5 Operation, Administration, and Maintenance (OAM) loopback cell generation and OAM management for all permanent virtual circuit (PVC) members of a bundle or a VC class that can be applied to a PVC bundle, use the oam-bundle command in VC-class configuration mode. To remove OAM management from the bundle or class configuration, use the no form of the command.

oam-bundle [manage] [frequency]

no oam-bundle [manage] [frequency]

Syntax Description

manage	(Optional) Enables OAM management. If you omit this keyword, loopback cells are sent, but the bundle is not managed.
frequency	(Optional) Number of seconds between transmitted OAM loopback cells. Valid values are from 0 to 600 seconds. The default value is 10 seconds.

oam-bundle Command History

Cisco IOS Release	Description
Release 12.0(26)S	This command was introduced on the PRE1.

Defaults

End-to-end F5 OAM loopback cell generation and OAM management are disabled, but if OAM cells are received, they are looped back.

Configuration Modes

VC-class configuration (for a VC class)

Bundle configuration (for an ATM VC bundle)

Usage Guidelines for the oam-bundle Command

This command defines whether a VC bundle is OAM managed. If this command is configured for a bundle, every VC member of the bundle is OAM managed. If OAM management is enabled, further control of OAM management is configured using the oam retry command.

This command has no effect if the VC class that contains the command is attached to a standalone VC; that is, if the VC is not a bundle member. In this case, the attributes are ignored by the VC.

To use this command in VC-class configuration mode, first enter the vc-class atm global configuration command.

To use this command in bundle configuration mode, enter the bundle subinterface configuration command to create the bundle or to specify an existing bundle before you enter this command.

VCs in a VC bundle are subject to the following configuration inheritance rules (listed in order of next-highest precedence):

•VC configuration in bundle-VC mode

•Bundle configuration in bundle mode (with effect of assigned VC-class configuration)

precedence Command

To configure precedence levels for a virtual circuit (VC) class that can be assigned to a VC bundle and thus applied to all VC members of that bundle, use the precedence command in vc-class configuration mode. To remove the precedence levels from the VC class, use the no form of the command.

To configure the precedence levels for a VC or permanent virtual circuit (PVC) member of a bundle, use the precedence command in bundle-vc configuration mode for ATM VC bundle members. To remove the precedence levels from the VC or PVC, use the no form of the command.

precedence [other | range]

no precedence 

Syntax Description

other	(Optional) Any precedence levels in the range from 0 to 7 that are not explicitly configured.
range	(Optional) A single precedence level specified either as a number from 0 to 7 or as a range of precedence levels, specified as a hyphenated range.

precedence Command History

Cisco IOS Release	Description
Release 12.0(26)S	This command was introduced on the PRE1.

Defaults

Defaults to other—that is, any precedence levels in the range from 0 to 7 that are not explicitly configured.

Configuration Modes

VC-class configuration (for a VC class)

Bundle-vc configuration (for ATM VC bundle members)

Usage Guidelines for the precedence Command

Assignment of precedence levels to VC or PVC bundle members allows you to create differentiated service because you can distribute the IP precedence levels over the various VC/PVC bundle members. You can map a single precedence level or a range of levels to each discrete VC/PVC in the bundle, thereby enabling VCs/PVCs in the bundle to carry packets marked with different precedence levels. Alternatively, you can use the precedence other command to indicate that a VC/PVC can carry traffic marked with precedence levels not specifically configured for other VCs/PVCs. Only one VC/PVC in the bundle can be configured using the precedence other command. This VC/PVC is the default VC/PVC.

To use this command in vc-class configuration mode, first enter the vc-class atm command in global configuration mode. The precedence command has no effect if the VC class that contains the command is attached to a standalone VC; that is, if the VC is not a bundle member.

To use the precedence command to configure an individual bundle member in bundle-VC configuration mode, first enter the bundle command to enter bundle configuration mode. Next, use the pvc-bundle command to add a PVC to the bundle as a member of the bundle and enter bundle-VC configuration mode.

VCs in a VC bundle are subject to the following configuration inheritance guidelines (listed in order of next-highest precedence):

•VC configuration in bundle-vc mode

•Bundle configuration in bundle mode (with effect of assigned vc-class configuration)

•Subinterface configuration in subinterface mode

protect Command

To configure a virtual circuit (VC) class with protected group or protected VC status for application to a VC bundle member, use the protect command in vc-class configuration mode. To remove the protected status from the VC class, use the no form of the command.

To configure a specific VC or permanent virtual circuit (PVC) as part of a protected group of the bundle or to configure it as an individually protected VC or PVC bundle member, use the protect command in bundle-vc configuration mode. To remove the protected status from the VC or PVC, use the no form of the command.

protect {group | vc}

no protect {group | vc} 

Syntax Description

group	Configures the VC or PVC bundle member as part of the protected group of the bundle.
vc	Configures the VC or PVC member as individually protected.

protect Command History

Cisco IOS Release	Description
Release 12.0(26)S	This command was introduced on the PRE1.

Defaults

The VC or PVC neither belongs to the protected group nor is it an individually protected VC or PVC.

Configuration Modes

VC-class configuration (for a VC class)

Bundle-vc configuration (for ATM VC bundle members)

Usage Guidelines for the protect Command

Use the protect command in vc-class configuration mode to configure a VC class to contain protected group or individual protected VC status. When the class is applied to the VC bundle member, that VC is characterized by the protected status. You can also apply this command directly to a VC in bundle-vc configuration mode.

When a protected VC goes down, it takes the bundle down. When all members of a protected group go down, the bundle goes down.

To use the protect command in vc-class configuration mode, first enter the vc-class atm global configuration command.

The protect command has no effect if the VC class that contains the command is attached to a standalone VC, that is, if the VC is not a bundle member.

To use the protect command in bundle-vc configuration mode, first enter the bundle command to enact bundle configuration mode for the bundle containing the VC member to be configured. Then enter the pvc-bundle configuration command to add the VC to the bundle as a member of it.

VCs in a VC bundle are subject to the following configuration inheritance guidelines (listed in order of next highest precedence):

•VC configuration in bundle-vc mode

•Bundle configuration in bundle mode (with effect of assigned vc-class configuration)

•Subinterface configuration in subinterface mode

pvc-bundle Command

To add a permanent virtual circuit (PVC) to a bundle as a member of the bundle and enter bundle-vc configuration mode in order to configure that PVC bundle member, use the pvc-bundle command in bundle configuration mode. To remove the VC from the bundle, use the no form of the command.

pvc-bundle pvc-name [vpi/] [vci]

no pvc-bundle pvc-name [vpi/] [vci] 

Syntax Description

pvc-name	The name of the permanent virtual circuit (PVC) bundle.
vpi/	(Optional) ATM network virtual path identifier (VPI) for this PVC. The absence of the "/" and a vpi value defaults the vpi value to 0. The vpi and vci arguments cannot both be set to 0; if one is 0, the other cannot be 0.
vci	(Optional) ATM network virtual channel identifier (VCI) for this PVC. The value range is from 0 to 1 less than the maximum value set for this interface by the atm vc-per-vp command. Typically, lower values 0 to 31 are reserved for specific traffic (F4 Operation, Administration, and Maintenance (OAM), Integrated Local Management Interface (ILMI), and so on) and should not be used. The VCI is a 16-bit field in the header of the ATM cell. The VCI value is unique only on a single link, not throughout the ATM network, because it has local significance only. The vpi and vci arguments cannot both be set to 0; if one is 0, the other cannot be 0.

pvc-bundle Command History

Cisco IOS Release	Description
Release 12.0(26)S	This command was introduced on the PRE1.

Defaults

No default behavior or values.

Configuration Modes

Bundle configuration

Usage Guidelines for the pvc-bundle Command

Each bundle can contain multiple VCs having different QoS attributes. This command associates a VC with a bundle, making it a member of that bundle. Before you can add a VC to a bundle, the bundle must exist. Use the bundle command to create a bundle. You can also use this command to configure a VC that already belongs to a bundle. You enter the command in the same way, giving the name of the VC bundle member.

The pvc-bundle command enters bundle-vc configuration mode, in which you can specify VC-specific and VC class attributes for the VC.

ATM Bundle Management

ATM PVC bundle management software allows you to configure multiple PVCs that have different QoS characteristics between any pair of ATM-connected routers. As shown in Figure 19-2, these PVCs are grouped in a bundle and are referred to as bundle members.

Figure 19-2 ATM VC Bundle

ATM PVC bundle management allows you to define an ATM PVC bundle and add PVCs to it. Each PVC of a bundle has its own ATM traffic class and ATM traffic parameters. You can apply attributes and characteristics to discrete PVC bundle members or you can apply them collectively at the bundle level.

Using PVC bundles, you can create differentiated service by flexibly distributing IP precedence levels or Multiprotocol Label Switching (MPLS) experimental (EXP) levels over the different PVC bundle members. You can map a single level or a range of levels to each discrete PVC in the bundle, thereby enabling individual PVCs in the bundle to carry packets marked with different precedence or MPLS EXP levels. You can use weighted random early detection (WRED) to further differentiate service across traffic that has different IP precedence or MPLS EXP levels, but that uses the same PVC in a bundle.

To determine which PVC in the bundle to use to forward a packet to its destination, the ATM PVC bundle management software matches precedence levels or MPLS EXP levels between packets and PVCs (see Figure 19-3). IP traffic is sent to the next hop address for the bundle because all PVCs in a bundle share the same destination, but the PVC used to carry a packet depends on the value set for that packet in the IP precedence bits or the MPLS EXP bits of the type of service (ToS) byte of its header. The ATM PVC bundle management software matches the IP precedence or MPLS EXP level of the packet to the IP precedence or MPLS EXP value or range of values assigned to a PVC, sending the packet out on the appropriate VC.

The ATM PVC bundle management software also allows you to configure how traffic is redirected when the PVC the packet was matched to goes down. Figure 19-3 shows how the ATM PVC bundle management software determines which PVC bundle member to use to carry a packet and how WRED is used to differentiate traffic on the same VC. In the figure PVC selection is based on IP precedence levels, but it can also be based on MPLS EXP levels.

Figure 19-3 ATM PVC Selection

Bumping and ATM PVC Bundles

The ATM Operation, Administration, and Maintenance (OAM) polling mechanisms maintain the integrity of the PVCs in an ATM PVC bundle. These mechanisms determine whether a PVC is unavailable or severely congested. If an individual circuit become unavailable, then the device consults a preset series of rules to determine the course of action to take next. You configure specific parameters to define these rules.

Figure 19-4 conceptualizes a failed PVC bundle member whose failure calls into effect the configured bumping rules.

Figure 19-4 PVC Bundle Member Circuit Failure Enacting Bumping Rules

In the event of failure, the router responds with one of two methods:

•The first method dynamically assigns the traffic bound on the failed PVC to an alternative PVC, which is referred to as circuit bumping. Bumped traffic is then shared on an existing in-service PVC. Although not required, traffic is typically bumped from a higher class to a lower one. For example, if the premium, or first class, data circuit become unavailable, then all premium users share the second class or general circuit. Within this shared circuit, preference is given to the premium traffic.

•The second method is to declare all circuits of the bundle to be down. In effect, the device is declaring the routed bundle inactive and asking the routing layer to search for an alternate.

The network configuration determines whether to bump traffic or whether to declare the bundle inactive.

Prerequisites for ATM PVC Selection

•The Cisco 10000 series router must be running Cisco IOS Release 12.0(26)S or later.

•To implement ATM PVC bundles between two routers, you must enable IP Cisco Express Forwarding (CEF) switching on the routers.

Restrictions and Limitations for ATM PVC Selection

PVCs

•In Cisco IOS Release 12.0(26)S, the ATM implementation of VC bundles is restricted to PVCs.

•You can configure a maximum of 8 PVCs in one PVC bundle.

•A PVC can be a member of one and only one PVC bundle.

•A PVC that is a bundle member cannot be used in any other capacity. For example, you cannot configure a PVC bundle member in a map statement.

•The Cisco 10000 router does not support automapping of PVCs or variable bit rate-real-time (VBR-rt) for PVCs.

•The Cisco 10000 router supports aal5snap and aal5mux encapsulation types for PVCs and multipoint and point-to-point subinterfaces.

VC Selection

•You can map one or multiple precedence or MPLS EXP levels to a single PVC; however, you cannot map multiple PVCs to one precedence or MPLS EXP level.

•A PVC bundle does not come up until you configure all of the precedence or MPLS EXP levels in the bundle.

•If you attach a VC class with bundle attributes to a PVC that is not configured as a member of a PVC bundle, the Cisco 10000 router ignores the bundle attributes.

ATM Inverse ARP

•You can enable or disable inverse ARP for the PVC bundle but not for individual PVCs in the bundle.

•ATM inverse ARP for IP uses the PVC configured with precedence level 6.

•Inverse ARP for protocols other than IP (for example, IPX) is disabled by default unless you explicitly configure it in the PVC bundle.

Packet Forwarding

•The Cisco 10000 router does not support fast switching of IP packets.

Configuring ATM Bundles

You can configure ATM bundles either directly or by associating a VC class with the bundle.

To configure ATM bundles, perform the following configuration tasks:

•Creating an ATM Bundle Directly

•Creating an ATM Bundle Using a VC Class

•Adding an ATM PVC to a PVC Bundle

Creating an ATM Bundle Directly

The router applies the parameters you configure in ATM bundle configuration mode to the PVC bundle and to all of the bundle members. These parameters supersede the parameters that you apply by associating a VC class with the bundle. Parameters that you apply to an individual PVC supersede the parameters that you apply to the bundle.

To create a PVC bundle directly, enter the following commands beginning in global configuration mode:

	Command	Purpose
Step 1	Router(config)# interface atm slot/module/port[.subinterface]	Creates or modifies an interface or subinterface. Enters interface or subinterface configuration mode.
Step 2	Router(config-subif)# mpls ip	(Optional) Enables MPLS forwarding of IPv4 packets along normally routed paths. You must configure this command if you configure MPLS EXP-based PVC selection.
Step 3	Router(config-subif)# bundle bundle-name	Creates or modifies the PVC bundle and enters ATM bundle configuration mode. bundle-name is the name of the bundle.
Step 4	Router(config-atm-vcb)# protocol protocol {protocol-address | inarp} [[no] broadcast]	Configures a static map for an ATM PVC or VC class, or enables Inverse Address Resolution Protocol (ARP) or Inverse ARP broadcasts on an ATM PVC. protocol is the protocol carried on the VC (for example, ip). protocol-address is the destination address that is being mapped to a PVC. (Valid only for IP and IPX protocols on PVCs) inarp enables Inverse ARP on an ATM PVC. If you specify a protocol-address instead of inarp, Inverse ARP is automatically disabled for that protocol. (Optional) [no] broadcast indicates that this map entry is used when the corresponding protocol sends broadcast packets to the interface. Pseudobroadcasting is supported. The broadcast keyword of the protocol command takes precedence if you previously configured the broadcast command on the ATM PVC.
Step 5	Router(config-atm-vcb)# encapsulation [aal5snap | aal5mux ip]	Configures the ATM adaptation layer (AAL) and encapsulation type for the bundle.
Step 6	Router(config-atm-vcb)# encapsulation {aal5mux protocol | aal5ciscoppp virtual-template number | aal5snap}	Configures the ATM adaptation layer (AAL) and encapsulation type for an ATM virtual circuit (VC). aal5mux is the AAL and encapsulation type for multiplex (MUX)-type VCs. You must specify a protocol when using this encapsulation type. protocol is the protocol type being used by the MUX-encapsulated VC. aal5ciscoppp specifies the AAL and encapsulation type for Cisco PPP over ATM. Supported on ATM PVCs only. virtual-template number is the number used to identify the virtual template. aal5snap specifies the AAL and encapsulation type that supports Inverse ARP. Logical Link Control/Subnetwork Access Protocol (LLC/SNAP) precedes the protocol datagram.
Step 7	Router(config-atm-vcb)# class class_name	(Optional) Attaches a VC class to the bundle. class_name is the name of the VC class.
Step 8	Router(config-atm-vcb)# inarp [minutes]	Configures the Inverse Address Resolution Protocol (ARP) time period for an ATM PVC, VC class, or VC bundle. minutes is the number of minutes for the Inverse ARP time period.
Step 9	Router(config-atm-vcb)# broadcast	Enables broadcast forwarding for all VC bundle members.
Step 10	Router(config-atm-vcb)# oam retry up-count down-count retry-frequency	Configures parameters related to Operation, Administration, and Maintenance (OAM) management for each PVC in the bundle. up-count is the number of consecutive end-to-end F5 OAM loopback cell responses that must be received in order to change a PVC connection state to up. down-count is the number of consecutive end-to-end F5 OAM loopback cell responses that are not received in order to change a PVC state to down. retry-frequency is the frequency (in seconds) that end-to-end F5 OAM loopback cells are transmitted when a change in the up/down state of a PVC is being verified. For example, if a PVC is up and a loopback cell response is not received after specifying retry-frequency, then loopback cells are sent at the retry-frequency to verify whether the PVC is down.
Step 11	Router(config-atm-vcb)# oam-bundle [manage] [frequency]	Enables end-to-end F5 Operation, Administration, and Maintenance (OAM) loopback cell generation and OAM management for all bundle members or a VC class that can be applied to a VC bundle (Optional) manage enables OAM management. If you omit this keyword, loopback cells are sent, but the bundle is not managed. (Optional) frequency is the number of seconds between transmitted OAM loopback cells. Valid values are from 0 to 600 seconds. The default is 10 seconds.
Step 12	Router(config-atm-vcb)# ubr [pcr]	Configures unspecified bit rate (UBR) as the traffic shaping rule. (Optional) pcr is the peak cell rate.
Step 13	Router(config-atm-vcb)# ubr+ pcr [mcr]	Configures UBR plus (UBR+) as the traffic shaping rule. pcr is the peak cell rate. (Optional) mcr is the minimum cell rate.
Step 14	Router(config-atm-vcb)# vbr-nrt pcr scr [mbs]	Configures variable bit rate-nonreal-time (VBR-nrt) as the traffic shaping rule. pcr is the peak cell rate. scr is the sustained cell rate. (Optional) mbs is the maximum burst size.

Creating an ATM Bundle Using a VC Class

You can use a VC class to configure an ATM PVC bundle. The VC class contains multiple configuration parameters, including the method used for PVC selection. When you apply the VC class to the bundle, the VC class parameters apply to all of the members of a bundle.

The parameters that you apply manually to the PVC bundle supersede the parameters that you apply by associating a VC class with the bundle. Parameters that you apply to an individual PVC supersede the parameters that you apply to a bundle.

To create an ATM bundle using a VC class, perform the following configuration tasks:

•Configuring a VC Class and Specifying the Basis for PVC Selection

•Attaching a VC Class to an ATM Bundle

Configuring a VC Class and Specifying the Basis for PVC Selection

To configure a VC class and specify the basis for PVC selection, enter the following commands beginning in global configuration mode:

	Command	Purpose
Step 1	Router(config)# vc-class atm name	Creates or modifies a VC class and enters VC class configuration mode. name is the name of the VC class.
Step 2	Router(config-vc-c)# oam-bundle [manage] [frequency]	Enables end-to-end F5 Operation, Administration, and Maintenance (OAM) loopback cell generation and OAM management for a VC class that can be applied to a VC bundle. (Optional) manage enables OAM management. If you omit this keyword, loopback cells are sent, but the bundle is not managed. (Optional) frequency is the number of seconds between transmitted OAM loopback cells. Valid values are from 0 to 600 seconds. The default is 10 seconds.
Step 3	Router(config-vc-c)# mpls experimental [other | range]	(Optional) Configures Multiprotocol Label Switching (MPLS) experimental (EXP) levels for a VC class that can be assigned to a VC bundle and thus applied to all VC members of that bundle. This command configures MPLS EXP-based PVC selection. (Optional) other specifies any MPLS EXP levels that are not explicitly configured. This is the default setting. (Optional) range specifies a single MPLS EXP level (2), or a range of levels (1-3). Valid values are from 0 to 7.
Step 4	Router(config-vc-c)# precedence {level | other}	(Optional) Configures the precedence levels for a bundle member. This command configures precedence-based PVC selection. level specifies the precedence level or levels for this bundle member. Valid values are from 0 to 7. You can configure a PVC bundle member with a single precedence level (0), multiple individual precedence levels (0,2,3), a range of precedence levels (0-2), multiple ranges of precedence levels (0-2,4-5), or a combination of individual levels and level ranges (0,1,2-4,7). Note This command is available when the PVC bundle match type is set to