Document ID: 22821 |
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:
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Cisco 7600 Internet Router Series running Cisco IOS Software Release 12.1(8a)E5 with a FlexWAN card and a PA-A3.
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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:
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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
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A Supervisor Engine 2 (SUP2) is recommended for better performance.
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LLQ is supported on all PAs in the FlexWAN.
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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.
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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
- IP to ATM Class of Service Overview
- ATM Technology Support
- IP to ATM Class of Service Technology Support
- FlexWAN Module for the Cisco 7600 Series Router and the Cisco Catalyst 6500 Series Switch
- Technical Support - Cisco Systems
| Updated: Dec 12, 2005 | Document ID: 22821 |