Configuring Subnetwork Bandwidth Manager

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.

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 (Required)

•Configuring the NonResvSendLimit Object (Optional)

•Verifying Configuration of SBM State (Optional)

See the end of this chapter for the section "Example: Subnetwork Bandwidth Manager Candidate Configuration."

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

Router(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

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

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

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

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

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

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

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

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

Router(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

Router# 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 router.

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: 

Router# 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: 

Router# 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

For information about configuring SBM, see the section "Subnetwork Bandwidth Manager Configuration Task List" in this chapter.

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

Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1005R)

Any Internet Protocol (IP) addresses used in this document are not intended to be actual addresses. Any examples, command display output, and figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses in illustrative content is unintentional and coincidental.

© 2007 Cisco Systems, Inc. All rights reserved.