Configuring Per-VC Queueing and IP to ATM CoS on the PA-A3 and FlexWAN [IP to ATM Class of Service]

Document ID: 22821

Introduction
Prerequisites
      Requirements
      Components Used
      Conventions
FlexWAN QoS Overview
Configure
      Network Diagram
      Configurations
Verify
      show Commands on the FlexWAN
      show Commands on the Cisco 7200 Router
Troubleshoot
Related Information

Introduction

This document provides a sample configuration and supported Cisco IOS® Software versions for applying per-virtual channel (VC) queueing and IP to ATM class of service (CoS) on a Cisco Enhanced ATM port adapter (PA-A3) when inserted in a FlexWAN on the Cisco 7600 Series Internet Router. IP to ATM CoS refers to per-VC, layer-3 queues, permanent virtual circuit (PVC) bundles, and quality of service (QoS) service policies that apply fancy queueing mechanisms such as class-based weighted fair queueing (CBWFQ) and low latency queueing (LLQ).

Prerequisites

Requirements

This document requires an understanding of IP to ATM CoS. The following resources provide information on these features:

Components Used

The sample configuration used in this document applies a policy-map with multiple classes to an ATM PVC. It was tested using this hardware and software:

Cisco 7600 Internet Router Series running Cisco IOS Software Release 12.1(8a)E5 with a FlexWAN card and a PA-A3.
Cisco 7206 VXR Router Series running Cisco IOS Software Release 12.2(7)a.

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.

Conventions

For more information on document conventions, refer to Cisco Technical Tips Conventions.

FlexWAN QoS Overview

The FlexWAN line card implements the distributed Cisco IOS architecture of the Cisco 7500, supports two Cisco 7200/7500 Port Adapters, and leverages the Cisco IOS code to provide its distributed QoS features. The FlexWAN does not use the Policy Feature Card 2 (PFC2) for its QoS services.

Cisco IOS Software Release 12.1(5)E introduced per-VC CBWFQ and LLQ service policies on the PA-A3 in the 7500 Series and on the FlexWAN with Multilayer Switch Feature Card (MSFC) IOS (Hybrid). Cisco IOS Software Release 12.1(8)E introduced support for the FlexWAN with Cisco IOS on the Supervisor Engine and MSFC2 (Native). Issue the service-policy output {name} command to attach a policy-map directly to an ATM PVC and achieve per-VC feature functionality. All the Modular QoS CLI (MQC) (MQC) commands—including police, set, bandwidth, priority, and shape—are supported.

When configuring QoS on the PA-A3 and the FlexWAN, note the following:

The PA-A3-OC3, PA-A3-T3, PA-A3-E3 and PA-A3-IMA Port Adapters are supported. Refer to Catalyst 6500 Series and Cisco 7600 Series Router FlexWAN Module Installation and Configuration Note to see the port adapters supported on the FlexWAN module. Distributed class-based weighted fair queueing (dCBWFQ) for PA-A3-inverse multiplexing over ATM (IMA) is introduced in Cisco IOS Software Release 12.1(11.5)E
A Supervisor Engine 2 (SUP2) is recommended for better performance.
LLQ is supported on all PAs in the FlexWAN.
Distributed Link Fragmentation and Interleaving (dLFI) over distributed multilink point-to-point (dMLPPP) bundle interfaces is planned for an upcoming release of Cisco IOS Software. Refer to Configuring CBWFQ and LLQ on MLPPP and Dialer Interfaces.
PVC bundles are planned for an upcoming release of Cisco IOS Software. Currently, the forwarding hardware supports only a single Cisco Express Forwarding (EF) adjacency, and packets with different interface processor precedence values are forwarded out the same VC. Cisco Bug ID CSCdv52260 (registered customers only) documents this issue for a Supervisor Engine 2 / MSFC 2.

Configure

In this section, you are presented with the information to configure the features described in this document.

Note: To find additional information on the commands used in this document, use the Command Lookup Tool (registered customers only) .

Network Diagram

This document uses this network setup:

The graphic shows an ATM connection between a Cisco 7600 Series Internet Router with a FlexWAN card and PA-A3, and a Cisco 7200 Series Router with a PA-A3.

Configurations

This sample configuration shows how a single variable bit rate-nonreal time (VBR-nrt) PVC can carry IP video (H.323) and data. It uses a service policy with the bandwidth command to provide minimum bandwidth guarantees to IP video and the H.323 control signaling. All data traffic is classified in the class-default class and receives a minimum bandwidth guarantee via weighted fair-queueing.

This sample configuration was created in a lab environment with a FlexWAN on one end of the PVC and a Cisco 7200 Series router on the other end of the PVC to illustrate the differences in supported commands and show command output between the two platforms.

7600 with FlexWAN

7200

class-map VoIP-Control 
  match ip precedence 3 
class-map Video 
  match ip precedence 4 
! 
policy-map WAN 
  class VoIP-Control 
    bandwidth 64 
  class Video 
    bandwidth 2000 
  class class-default 
    fair-queue 
! 
interface ATM7/0/0.98 point-to-point 
 bandwidth 4096 
 ip address 192.168.26.5 255.255.255.252 
 ip nbar protocol-discovery 
 ip pim sparse-dense-mode

!--- Multicast is configured
because we are carrying IP/TV
traffic.

 pvc 0/137  
  tx-ring-limit 4 
  vbr-nrt 6144 4096 1000 
  oam-pvc manage 2 
  oam retry 3 3 1 
  encapsulation aal5snap 
  protocol ip inarp 
  protocol ipx inarp 
  service-policy out WAN

class-map VoIP-Control 
  match ip precedence 3 
class-map Video 
  match ip precedence 4 
! 
policy-map WAN 
  class VoIP-Control 
    bandwidth 64 
  class Video 
    bandwidth 2000 
  class class-default 
    fair-queue 
! 
interface ATM2/0.98 point-to-point 
 bandwidth 4096 
 ip address 192.168.26.6 255.255.255.252 
 ip nbar protocol-discovery 
 ip pim sparse-dense-mode

!--- Multicast is configured
because we are carrying IP/TV
traffic.

 pvc 0/237  
  vbr-nrt 6144 4096 1000 
  tx-ring-limit 4 
  oam-pvc manage 2 
  oam retry 3 3 1 
  encapsulation aal5snap 
  protocol ip inarp 
  protocol ipx inarp 
  service-policy output WAN

Verify

The show commands used to confirm your QoS configuration are different between the FlexWAN / Cisco 7500 Series and the Cisco 7200 Series. This table lists the differences:

	FlexWAN and 7500 Series	7200 Series
show policy-map interface	Yes	Yes
show queueing interface	Yes - Limited output.	Yes
show queue atm	Not supported. Use NetFlow to collect traffic flow information.	Yes

For guidance on interpreting the show policy-map command, refer to Understanding Packet Counters in show policy-map interface Output.

Certain show commands are supported by the Output Interpreter Tool (registered customers only) , which allows you to view an analysis of show command output.

show Commands on the FlexWAN

Use the show policy-map interface command to see traffic statistics for your service policy. This sample configuration applies a policy map with two configured classes. The class-map called VoIP-Control matches on H.323 control packets with an IP precedence of 3 and provides a minimum bandwidth guarantee of 64 kbps. The class-map called Video matches on packets with an IP precedence of 4 and provides a minimum bandwidth guarantee of 2 Mbps. For more information on applying QoS specifically in video over IP environments, refer to Implementing QoS Solutions for H.323 Video Conferencing Over IP.

svlab-7600# show policy-map interface atm 7/0/0.98 

 ATM7/0/0.98: VC 0/137 

  service-policy output: WAN 

    class-map: VoIP-Control (match-any) 
      0 packets, 0 bytes 
      30 second offered rate 0 bps, drop rate 0 bps 
      match: ip precedence 3 
        0 packets, 0 bytes 
        30 second rate 0 bps 
      queue size 0, queue limit 16 
      packets output 0, packet drops 0 
      tail/random drops 0, no buffer drops 0, other drops 0 
      bandwidth: kbps 64, weight 1 

    class-map: Video (match-any) 
      5229496 packets, 5509036180 bytes 
      30 second offered rate 1366000 bps, drop rate 0 bps 
      match: ip precedence 4 
        5229496 packets, 5509036180 bytes 
        30 second rate 1366000 bps 
      queue size 0, queue limit 77 
      packets output 5229496, packet drops 0 
      tail/random drops 0, no buffer drops 0, other drops 0 
      bandwidth: kbps 2000, weight 48 

    class-map: class-default (match-any) 
      1549597 packets, 1193836049 bytes 
      30 second offered rate 297000 bps, drop rate 0 bps 
      match: any 
        1549597 packets, 1193836049 bytes 
        30 second rate 297000 bps 
      queue size 0, queue limit 78 
      packets output 1550306, packet drops 0 
      tail/random drops 0, no buffer drops 0, other drops 0 
      fair-queue: per-flow queue limit 19 
      random-detect: 
        Exp-weight-constant: 9 (1/512) 
        Mean queue depth: 0 
        Class Random       Tail   Minimum   Maximum     Mark       Output 
                drop       drop threshold threshold  probability  packets 
        0          0          0        19        39     1/10      1521604 
        1          0          0        21        39     1/10            0 
        2          0          0        23        39     1/10            0 
        3          0          0        26        39     1/10            0 
        4          0          0        28        39     1/10            0 
        5          0          0        30        39     1/10            0 
        6          0          0        33        39     1/10            0 
        7          0          0        35        39     1/10            0

The show queue atm command is not supported on the FlexWAN, as shown here:

svlab-7600# show queue atm 7/0/0.98 
Show queue not supported with FIFO queueing 

svlab-7600# show queueing 
Current fair queue configuration: 
Current priority queue configuration: 
Current custom queue configuration: 
Current random-detect configuration: 

svlab-7600# show interface atm 7/0/0 
ATM7/0/0 is up, line protocol is up 
  Hardware is ENHANCED ATM PA 
  MTU 4470 bytes, sub MTU 4470, BW 149760 Kbit, DLY 80 usec, 
     reliability 255/255, txload 2/255, rxload 1/255 
  Encapsulation ATM, loopback not set 
  Keepalive not supported 
  Encapsulation(s): AAL5 
  1024 maximum active VCs, 2 current VCCs 
  VC idle disconnect time: 300 seconds 
  2 carrier transitions 
  Last input 00:00:00, output 00:00:00, output hang never 
  Last clearing of "show interface" counters never 
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0 
  Queueing strategy: fifo 
  
!--- Displays FIFO, even with an applied service policy.
 
  Output queue :0/40 (size/max) 
  30 second input rate 1000 bits/sec, 2 packets/sec 
  30 second output rate 1203000 bits/sec, 156 packets/sec 
  L2 Switched: ucast: 0 pkt, 0 bytes - mcast: 0 pkt, 0 bytes 
  L3 in Switched: ucast: 0 pkt, 0 bytes - mcast: 0 pkt, 0 bytes mcast 
  L3 out Switched: ucast: 0 pkt, 0 bytes 
     127206 packets input, 7780625 bytes, 0 no buffer 
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles 
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 
     6937035 packets output, 2482434516 bytes, 0 underruns 
     0 output errors, 0 collisions, 2 interface resets 
     0 output buffer failures, 0 output buffers swapped out

show Commands on the Cisco 7200 Router

This is sample output from the Cisco 7200 Router:

demo7206# show queueing interface atm 2/0.98 
  Interface ATM2/0.98 VC 0/237 
  Queueing strategy: weighted fair 
  Total output drops per VC: 0 
  Output queue: 0/512/64/0 (size/max total/threshold/drops) 
     Conversations  0/1/128 (active/max active/max total) 
     Reserved Conversations 2/2 (allocated/max allocated) 
     Available Bandwidth 1008 kilobits/sec 

demo7206# show queue atm 2/0.98 
  Interface ATM2/0.98 VC 0/237 
  Queueing strategy: weighted fair 
  Total output drops per VC: 0 
  Output queue: 0/512/64/0 (size/max total/threshold/drops) 
     Conversations  0/1/128 (active/max active/max total) 
     Reserved Conversations 2/2 (allocated/max allocated) 
     Available Bandwidth 1008 kilobits/sec 

demo7206# show interface atm 2/0 
ATM2/0 is up, line protocol is up 
  Hardware is ENHANCED ATM PA 
  MTU 4470 bytes, sub MTU 4470, BW 149760 Kbit, DLY 80 usec, 
     reliability 255/255, txload 1/255, rxload 2/255 
  Encapsulation ATM, loopback not set 
  Encapsulation(s): AAL5 
  4095 maximum active VCs, 2 current VCCs 
  VC idle disconnect time: 300 seconds 
  0 carrier transitions 
  Last input 00:00:00, output 00:00:00, output hang never 
  Last clearing of "show interface" counters never 
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0 
  Queueing strategy: Per VC Queueing 
  
!--- Displays as Per VC Queueing automatically in supporting 
!--- Cisco IOS Software releases.
 
  30 second input rate 1356000 bits/sec, 173 packets/sec 
  30 second output rate 2000 bits/sec, 4 packets/sec 
     6925985 packets input, 2471960702 bytes, 0 no buffer 
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles 
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 
     126965 packets output, 7890516 bytes, 0 underruns 
     0 output errors, 0 collisions, 0 interface resets 
     0 output buffer failures, 0 output buffers swapped out

Troubleshoot

There is currently no specific troubleshooting information available for this configuration.

Related Information

Updated: Dec 12, 2005

Document ID: 22821

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IP to ATM Class of Service