ATM Traffic Management

Document ID: 10445

Contents

Introduction
VP Shaping Restrictions
      Restrictions
      Conventions
Configure
      Sample Configuration
      Show Commands
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Related Information

Introduction

This document provides a sample configuration for VP shaping on the 4xOC3 ATM line card for the Gigabit Switch Router (GSR). VP shaping was introduced in Cisco IOS^® software release 12.0(8)S.

In order to use this feature, configure a permanent virtual path (PVP) with a specific virtual path identifier (VPI). Any PVCs that use the same VPI number are multiplexed onto the PVP.

VP shaping configures the router to regulate the output rate of the PVP rather than the output rate of individual PVCs. The router ignores the traffic parameters of individual PVCs. Instead, all PVCs use the same peak cell rate (PCR) as the PVP.

When you create a PVP, the router creates two PVCs for end-to-end loopback and segment loopback operations, administration, and maintenance (OAM) cells. OAM cells at the VP level use the same VPI value as the user cells of the PVP and use defined or "well-known" VCI values. These VCI values are 3 for segment OAM F4 flow and 4 for end-to-end OAM F4 flow.

VP Shaping Restrictions

Restrictions

These restrictions apply to VP shaping on the 4xOC3 ATM line card:

• Up to 64 PVPs are supported on a single ATM interface.

• A PVP supports VCs of the UBR service class only. Hierarchical VP shaping, in which the member VCs use different PCRs or ATM service classes, such as nrt-VBR, is not supported.

• All VCs share the same PCR as the PVP. The cell scheduler assigns the same priority to all VCs within the PVP and services each VC on a best-effort basis.

Conventions

Refer to Cisco Technical Tips Conventions for more information on document conventions.

Configure

Note: Use the Command Lookup Tool ( registered customers only) to find more information on the commands used in this document.

Sample Configuration

Follow these steps:

1. Create a PVP and optionally specify the peak rate.

2. Create a PVC with a VPI that matches the VPI specified in step one.

3. Exit configuration mode and execute the show atm vp command to confirm your configuration.

interface ATM7/0 
  no ip address  
  atm pvp 10 25000  
  no atm ilmi-keepalive  
 !  
interface ATM7/0.5 multipoint
  ip address 5.5.5.1 255.255.255.0  
  pvc 10/100  
   protocol ip 5.5.5.2  
 ! 
interface ATM7/0.10 point-to-point  
  ip address 10.10.10.1 255.255.255.0  
  pvc 10/110

Note these key points about the configuration:

• If you create PVCs with the old-style atm pvc command, the GSR command-line interface (CLI) does not provide the option to configure traffic-shaping values that are different from the values of the PVP. This behavior is correct since the GSR ATM line cards do not support hierarchical VP shaping.

  GSR-1(config)#int atm 7/0
  

  GSR-1(config-if)#atm pvc 100 10 100 aal5snap ? 
    bridge         1483 bridge-encapsulation enable 
    inarp          Inverse ARP enable 
    oam            OAM loopback enable 
    random-detect  WRED enable 
    <cr> 
  

• If you create PVCs with the new-style pvc vpi/vci command, the CLI allows you to configure a shaped nrt-VBR VC with the same VPI as a VP tunnel, but the GSR line card silently creates an unshaped VC. The only shaping applied to any VC inside a VP tunnel is the shaping applied to the VP tunnel that encloses the VC.

• The ability to apply the ubr+ command to a VC with the same VPI as a VP tunnel was removed in Cisco IOS release 12.0(13.6)S (CSCds49283).

Show Commands

• show atm vp - Displays the configuration of the PVP.

  GSR-1#show atm vp
                      Data  CES    Peak    CES 
  Interface    VPI    VCs   VCs    Kbps    Kbps     Status 
  ATM7/0       10     2     0      25000   0        ACTIVE 
  

• show atm vp {vpi#} - Displays packet counts for each PVC and for the PVP overall.

  ATM7/0  VPI: 10, PeakRate: 25000, CesRate: 0, DataVCs: 2, CesVCs: 0, Status: ACTIVE 
    VCD    VCI   Type   InPkts   OutPkts   AAL/Encap     Status 
    1      3     PVC    0        0         F4 OAM        ACTIVE 
    2      4     PVC    0        112       F4 OAM        ACTIVE 
    3      100   PVC    0        0         AAL5-SNAP     ACTIVE 
    4      10    PVC    0        0         AAL5-SNAP     ACTIVE 
  
  TotalInPkts: 0, TotalOutPkts: 112, TotalInFast: 0, TotalOutFast: 112, TotalBroadcasts: 0 
  

• show atm vc —Displays the encapsulation and shaping parameters of the PVCs in the PVP.

• show atm vc {vcd#} —Displays packet counts and other statistics per VC.

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Related Information

• Quad OC-3 ATM Line Card Configuration and Installation
• Configuring ATM, Cisco IOS Wide-Area Networking Configuration Guide
• ATM Technology Support Pages
• Technical Support & Documentation - Cisco Systems