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Cisco IOS XE Quality of Service Solutions Configuration Guide, Release 2
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Quality of Service Overview
- Part 1: Classification
- Part 2: Congestion Management
- Part 3: Congestion Avoidance
- Part 4: Policing and Shaping
- Part 5: Link Efficiency Mechanisms
- Part 6: Quality of Service Solutions
- Part 7: Modular Quality of Service Command-Line Interface
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Table Of Contents
QoS: Classification, Policing, and Marking on a LAC
Prerequisites for QoS: Classification, Policing, and Marking on a LAC
Restrictions for QoS: Classification, Policing, and Marking on a LAC
Information About QoS: Classification, Policing, and Marking on a LAC
Benefits of the QoS: Classification, Policing, and Marking on a LAC Feature
Upstream Traffic from the LAC to the LNS
Downstream Traffic from the LNS to the LAC
How to Configure QoS: Classification, Policing, and Marking on a LAC
Enabling the Service Provider to Verify Traffic Statistics
Configuration Examples for QoS: Classification, Policing, and Marking on a LAC
Configuring the Routers: Example
Verifying the SSS Session: Example
Applying the QoS Policy Map: Example
Verifying the QoS Policy Map for Downstream Traffic: Example
Applying the QoS Policy Map to the Session: Example
Verifying the QoS Policy Map for Upstream Traffic: Example
Feature Information for QoS: Classification, Policing, and Marking on a LAC
QoS: Classification, Policing, and Marking on a LAC
First Published: May 27, 2004Last Updated: March 2, 2009The QoS: Classification, Policing, and Marking on a LAC feature allows service providers to classify packets based upon the IP type of service (ToS) bits in an embedded IP packet. The classification is used to police the incoming traffic according to the differentiated services code point (DSCP) value. The purpose of classifying the packet by examining its encapsulation is to simplify the implementation and configuration needed for a large number of PPP sessions.
Finding Feature Information
For the latest feature information and caveats, see 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 for QoS: Classification, Policing, and Marking on a LAC" section.
Use Cisco Feature Navigator to find information about platform support and Cisco IOS XE Software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Contents
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Prerequisites for QoS: Classification, Policing, and Marking on a LAC
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Prerequisites for QoS: Classification, Policing, and Marking on a LAC
Configure the Routers
You must configure the client router, the Layer 2 Tunneling Protocol (L2TP) Access Concentrator (LAC), and the L2TP Network Server (LNS) before applying the QoS policy map as described in the "Configuration Examples for QoS: Classification, Policing, and Marking on a LAC" section.
Verify the State of the Subscriber Service Switch Sessions
You must use the show sss session command to verify that the user sessions are enabled on a LAC.
Configure the Interface
You must configure the virtual-template interface before applying the policy map to the session.
Restrictions for QoS: Classification, Policing, and Marking on a LAC
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Information About QoS: Classification, Policing, and Marking on a LAC
To use the QoS: Classification, Policing, and Marking on a LAC feature, you should understand the following concepts:
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Benefits of the QoS: Classification, Policing, and Marking on a LAC Feature
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QoS Policy Maps and a LAC
QoS policing and marking can be achieved by attaching a QoS policy map to the user interface on a LAC in the input and output directions. By using tunnels, input and output service policies can be attached to interfaces. Policy maps get enforced as the packet enters or leaves the tunnel.
Figure 1 shows the deployment of QoS on PPPoE sessions originating at the client and terminating at the LNS.
Figure 1 Sample Topology for QoS on PPoE Sessions
Upstream Traffic from the LAC to the LNS
Upstream traffic corresponds to packets traversing from the tunnel source to the tunnel destination; in this case, the traffic moves from the LAC to the LNS. The input QoS policy map acts on the upstream traffic before the packet gets encapsulated with the tunnel header.
Downstream Traffic from the LNS to the LAC
Downstream traffic corresponds to packets traversing from the tunnel destination to tunnel source; in this case, the traffic going from the LNS to the LAC. The output QoS policy map acts on the downstream traffic after the tunnel encapsulation is removed from the packet header.
SSS Sessions on the LAC
The Subscriber Service Switch (SSS) session provides you with the infrastructure to apply QoS features on a per-session basis. The SSS session is preconfigured on the virtual template, and you can use this template to provide QoS classification, policing, and marking.
You can verify the statistics of the upstream and downstream traffic from a QoS policy map in an SSS session by using the show policy-map session command.
How to Configure QoS: Classification, Policing, and Marking on a LAC
This section contains the following task:
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Enabling the Service Provider to Verify Traffic Statistics
To enable a service provider to verify the statistics of the upstream and downstream traffic from a QoS policy map in an SSS session, perform the following steps.
SUMMARY STEPS
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DETAILED STEPS
Configuration Examples for QoS: Classification, Policing, and Marking on a LAC
This section contains the following configuration examples:
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Configuring the Routers: Example
The following example shows the configuration of the routers before the QoS policy map is verified.
Client Configuration
When you log in to the PC, a PPPoE session is established at the client that faces the LAC. This PPPoE session is forwarded through the L2TP tunnel from the LAC to the LNS at which point the PPPoE session terminates.
To apply QoS sessions to the user traffic that originates from the PC to the web server and to the traffic that originates from the web server to the PC, you should apply a QoS policy map to the user session on the LAC in the input and output directions. The classification will be based on the user traffic that originates at the PC and the web traffic that originates at the web server.
This topology supports bidirectional traffic, meaning that traffic can flow from the PC to the web server and from the web server to the PC.
username xyz@cisco.com password 0 password1username qos4-72a password 0 password1username qos4-72b password 0 password1aaa authentication ppp default localaaa session-id commonip cefvpdn enable!vpdn-group 1request-dialinprotocol pppoe!pppoe-forwardinginterface ATM0/0/0no ip addressno ip redirectsno ip proxy-arpno ip mroute-cacheload-interval 30no atm ilmi-keepalive!interface ATM0/0/0.1 point-to-pointpvc 0/100encapsulation aal5snappppoe max-sessions 100pppoe-client dial-pool-number 1!interface Dialer1mtu 1492ip address negotiatedencapsulation pppdialer pool 1no peer default ip addressno cdp enableppp authentication chap callinppp chap hostname xyz@cisco.comppp chap password 0 ciscoppp ipcp dns request!LAC Configuration
The following example shows that the interfaces between the client and the LAC are ATM5/0 interfaces.
username xyz@cisco.com password 0 password1username qos4-72a password 0 password1username qos4-72b password 0 password1aaa new-model!!aaa authentication ppp default localaaa session-id commonip cefvpdn enable!vpdn-group 1accept-dialinprotocol pppoevirtual-template 1!vpdn-group 2request-dialinprotocol l2tpdomain cisco.cominitiate-to ip 10.10.101.2local name lacno l2tp tunnel authenticationip tos reflect!pppoe-forwardinginterface Serial0/0/0bandwidth 2015ip address 10.10.100.1 255.255.255.0no ip redirectsno ip proxy-arpload-interval 30no keepaliveno cdp enable!interface ATM0/0/0no ip addressno ip redirectsno ip proxy-arpload-interval 30no atm ilmi-keepalive!interface ATM0/0/0.1 point-to-pointpvc 0/100encapsulation aal5snappppoe max-sessions 100protocol ppp Virtual-Template1protocol pppoe!!interface Virtual-Template1mtu 1492no ip addressno peer default ip addressppp authentication chap!LNS Configuration
The following example shows that the interface between the LAC and the LNS is a Serial3/6 interface.
username xyz@cisco.com password 0 password1username qos4-72b password 0 password1username qos4-72a password 0 password1aaa new-model!!aaa authentication ppp default localaaa session-id commonip cefvpdn enable!vpdn-group 1accept-dialinprotocol anyvirtual-template 1terminate-from hostname laclocal name lnslcp renegotiation alwaysno l2tp tunnel authenticationip tos reflect!interface Serial0/0/0bandwidth 2015ip address 10.10.100.1 255.255.255.0no ip redirectsno ip proxy-arpno ip mroute-cacheload-interval 30no keepaliveno cdp enable!Verifying the SSS Session: Example
The following example from the show sss session command shows that a user session is enabled on the LAC:
Router# show sss sessionCurrent SSS Information: Total sessions 1Uniq ID Type State Service Identifier Last Chg401 PPPoE/PPP connected Forwarded xyz@cisco.com 00:02:06Applying the QoS Policy Map: Example
The following output shows a QoS policy map to be applied to the user session in the output direction, which is the downstream traffic coming into the PC from the web server. The first subclass of traffic within the session is marked with dscp af11, the second subclass is policed, and the third subclass is dropped.
class-map match-any customer1234match ip dscp cs1 cs2 cs3 cs4class-map match-any customer56match ip dscp cs5 cs6class-map match-any customer7match ip dscp cs7policy-map downstream-policyclass customer1234set ip dscp af11class customer56police cir 20000 bc 10000 pir 40000 be 10000conform-action set-dscp-transmit af21exceed-action set-dscp-transmit af22violate-action set-dscp-transmit af23class customer7dropConfiguring the LAC: Example
The following example from the interface virtual-template command shows a QoS policy map being applied to the user session on the LAC:
Router# configure terminalRouter(config)# interface virtual-template1Router(config-if)# service-policy output downstream-policyRouter(config-if)# endVerifying the QoS Policy Map for Downstream Traffic: Example
In the following example from the show policy-map session command, the QoS policy map is applied for traffic in the downstream direction.
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Router# show policy-map session uid 401 outputSSS session identifier 401 -Service-policy output: downstream-policyClass-map: customer1234 (match-any)4464 packets, 249984 bytes5 minute offered rate 17000 bps, drop rate 0 bpsMatch: ip dscp cs1 cs2 cs3 cs44464 packets, 249984 bytes5 minute rate 17000 bpsQoS Setdscp af11Packets marked 4464Class-map: customer56 (match-any)2232 packets, 124992 bytes5 minute offered rate 8000 bps, drop rate 0 bpsMatch: ip dscp cs5 cs62232 packets, 124992 bytes5 minute rate 8000 bpspolice:cir 20000 bps, bc 10000 bytespir 40000 bps, be 10000 bytesconformed 2232 packets, 124992 bytes; actions:set-dscp-transmit af21exceeded 0 packets, 0 bytes; actions:set-dscp-transmit af22violated 0 packets, 0 bytes; actions:set-dscp-transmit af23conformed 8000 bps, exceed 0 bps, violate 0 bpsClass-map: customer7 (match-any)1116 packets, 62496 bytes5 minute offered rate 4000 bps, drop rate 4000 bpsMatch: ip dscp cs71116 packets, 62496 bytes5 minute rate 4000 bpsdropClass-map: class-default (match-any)1236 packets, 68272 bytes5 minute offered rate 4000 bps, drop rate 0 bpsMatch: anyApplying the QoS Policy Map to the Session: Example
In the following example, the service provider applies a QoS policy map to the user session in order to limit the amount of bandwidth that the user session is permitted to consume in the upstream direction from the PC to the web server.
Router# configure terminalRouter(config)# policy-map upstream-policyRouter(config-pmap)# class class-defaultRouter(config-pmap-c) police cir 8000 bc 1500 be 1500 conform-action transmit exceed-action dropRouter(config-if)# endThis QoS policy map is then applied to the user session as follows:
Router# configure terminalRouter(config)# interface virtual-template1Router(config-if)# service-policy input upstream-policyRouter(config-if)# endVerifying the QoS Policy Map for Upstream Traffic: Example
In the following example from the show policy-map session command, the QoS policy map is applied for traffic in the upstream direction.
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Router# show policy-map session uid 401 inputSSS session identifier 401 -Service-policy input: upstream-policyClass-map: class-default (match-any)1920 packets, 111264 bytes5 minute offered rate 7000 bps, drop rate 5000 bpsMatch: anypolice:cir 8000 bps, bc 1500 bytesconformed 488 packets, 29452 bytes; actions:transmitexceeded 1432 packets, 81812 bytes; actions:dropconformed 7000 bps, exceed 5000 bpsAdditional References
The following sections provide references related to the QoS: Classification, Policing, and Marking on a LAC feature.
Related Documents
Standards
No new or modified standards are supported, and support for existing standards has not been modified.
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MIBs
RFCs
No new or modified RFCs are supported, and support for existing RFCs has not been modified.
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Technical Assistance
Feature Information for QoS: Classification, Policing, and Marking on a LAC
Table 1 lists the release history for this feature.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS XE 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.
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Glossary
DSCP—differentiated services code point. A marker in the header of an IP packet that indicates the per-hop behavior given to the packet within the service provider network.
L2TP—Layer 2 Tunneling Protocol. An Internet Engineering Task Force (IETF) standards track protocol defined in RFC 2661 that provides tunneling of PPP. Based upon the best features of L2F and PPTP, L2TP provides an industry-wide interoperable method of implementing virtual private dialup network (VPDN).
LAC—Layer 2 Tunneling Protocol (L2TP) access concentrator. A node that acts as one side of an L2TP tunnel endpoint and is a peer to the L2TP network server (LNS). The LAC sits between an LNS and a remote system and forwards packets to and from each. Packets sent from the LAC to the LNS require tunneling with the L2TP protocol. The connection from the LAC to the remote system is either local or a PPP link.
LNS—L2TP network server. A node that acts as one side of an L2TP tunnel endpoint and is a peer to the L2TP access concentrator (LAC). The LNS is the logical termination point of a PPP session that is being tunneled from the remote system by the LAC.
PPoE—Point-to-Point Protocol over Ethernet. A feature that allows a PPP session to be initiated on a simple bridging Ethernet connected client. PPPoE provides the ability to connect a network of hosts over a simple bridging access device to a remote access concentrator or aggregation concentrator.
QoS—quality of service. A measure of performance for a transmission system that reflects its transmission quality and service availability.
SSS—Subscriber Service Switch. A switch that provides flexibility on where and how many subscribers are connected to available services and how those services are defined. The primary focus of SSS is to direct PPP from one point to another using a Layer 2 subscriber policy. The policy will manage tunneling of PPP in a policy-based bridging fashion.
ToS—type of service. An 8-bit field carried in an Internet Protocol Version 4 (IPv4) header that can be used to identify packets designated to receive preferential treatment on a class of service (CoS) basis.
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