Configuring Subnetwork Bandwidth Manager

Last Updated: October 11, 2012

This chapter describes the tasks for configuring the Subnetwork Bandwidth Manager (SBM) feature, which is a signalling feature that enables Resource Reservation Protocol (RSVP)-based admission control over IEEE 802-styled networks.

For complete conceptual information, see "Signalling Overview" module.

For a complete description of the SBM commands in this chapter, see the Cisco IOS Quality of Service Solutions Command Reference. To locate documentation of other commands that appear in this chapter, use the command reference master index or search online.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS and Catalyst OS software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn . An account on Cisco.com is not required.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.

Subnetwork Bandwidth Manager Configuration Task List

To configure SBM, perform the tasks described in the following sections. The task in the first section is required; the tasks in the remaining sections are optional.

Configuring an Interface as a Designated SBM Candidate

SBM is used in conjunction with RSVP. Therefore, before you configure an interface as a Designated SBM (DSBM) contender, ensure that RSVP is enabled on that interface.

To configure the interface as a DSBM candidate, use the following command in interface configuration mode:

Command

Purpose 

Device(config-if)# ip rsvp dsbm candidate [priority]

Configures the interface to participate as a contender in the DSBM dynamic election process, whose winner is based on the highest priority.

Configuring the NonResvSendLimit Object

The NonResvSendLimit object specifies how much traffic can be sent onto a managed segment without a valid RSVP reservation.

To configure the NonResvSendLimit object parameters, use the following commands in interface configuration mode, as needed:

Command

Purpose 

Device(config-if)# ip rsvp dsbm non-resv-send-limit rate  kBps

Configures the average rate, in kbps, for the DSBM candidate. 

Device(config-if)# ip rsvp dsbm non-resv-send-limit burst  kilobytes

Configures the maximum burst size, in KB, for the DSBM candidate. 

Device(config-if)# ip rsvp dsbm non-resv-send-limit peak  kBps

Configures the peak rate, in kbps, for the DSBM candidate. 

Device(config-if)# ip rsvp dsbm non-resv-send-limit min-unit  bytes

Configures the minimum policed unit, in bytes, for the DSBM candidate. 

Device(config-if)# ip rsvp dsbm non-resv-send-limit max-unit  bytes

Configures the maximum packet size, in bytes, for the DSBM candidate.

To configure the per-flow limit on the amount of traffic that can be sent without a valid RSVP reservation, configure the rate, burst, peak, min-unit, and max-unit keywords for finite values from 0 to infinity.

To allow all traffic to be sent without a valid RSVP reservation, configure the rate, burst, peak, min-unit, and max-unit keywords for unlimited. To configure the parameters for unlimited, you can either omit the command or enter the no version of the command (for example, no ip rsvp dsbm non-resv-send-limit rate). Unlimited is the default value.

The absence of the NonResvSendLimit object allows any amount of traffic to be sent without a valid RSVP reservation.

Verifying Configuration of SBM State

To display information that enables you to determine if an interface has been configured as a DSBM candidate and which of the contenders has been elected the DSBM, use the following command in EXEC mode:

Command

Purpose 

Device# show ip rsvp sbm [detail] [interface]

Displays information about an SBM configured for a specific RSVP-enabled interface or for all RSVP-enabled interfaces on the device.

Using the detail keyword allows you to view the values for the NonResvSendLimit object.

The displayed output from the show ip rsvp sbm command identifies the interface by name and IP address, and it shows whether the interface has been configured as a DSBM contender. If the interface is a contender, the DSBM Priority field displays its priority. The DSBM election process is dynamic, addressing any new contenders configured as participants. Consequently, at any given time, an incumbent DSBM might be replaced by one configured with a higher priority. The following example shows sample output from the show ip rsvp sbm command: 

Device# show ip rsvp sbm
Interface DSBM Addr      DSBM Priority    DSBM Candidate   My Priority
Et1      1.1.1.1         70               yes              70
Et2      145.2.2.150     100              yes              100

If you use the detail keyword, the output is shown in a different format. In the left column, the local DSBM candidate configuration is shown; in the right column, the corresponding information for the current DSBM is shown. In the following example, the local DSBM candidate won election and is the current DSBM: 

Device# show ip rsvp sbm detail
Interface:Ethernet2
Local Configuration             Current DSBM
  IP Address:10.2.2.150         IP Address:10.2.2.150
  DSBM candidate:yes             I Am DSBM:yes
  Priority:100                   Priority:100
  Non Resv Send Limit             Non Resv Send Limit
    Rate:500 Kbytes/sec            Rate:500 Kbytes/sec
    Burst:1000 Kbytes              Burst:1000 Kbytes
    Peak:500 Kbytes/sec            Peak:500 Kbytes/sec
    Min Unit:unlimited             Min Unit:unlimited
    Max Unit:unlimited             Max Unit:unlimited

Example Subnetwork Bandwidth Manager Candidate Configuration

In the following example, RSVP and SBM are enabled on Ethernet interface 2. After RSVP is enabled, the interface is configured as a DSBM and SBM candidate with a priority of 100. The configured priority is high, making this interface a good contender for DSBM status. However, the maximum configurable priority value is 128, so another interface configured with a higher priority could win the election and become the DSBM.

interface Ethernet2
 ip address 145.2.2.150 255.255.255.0
 no ip directed-broadcast
 ip pim sparse-dense-mode
 no ip mroute-cache
 media-type 10BaseT
 ip rsvp bandwidth 7500 7500
 ip rsvp dsbm candidate 100
 ip rsvp dsbm non-resv-send-limit rate 500
 ip rsvp dsbm non-resv-send-limit burst 1000
 ip rsvp dsbm non-resv-send-limit peak 500
end

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