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Control Plane Policing

Table Of Contents

Control Plane Policing

Finding Feature Information

Contents

Prerequisites for Control Plane Policing

Restrictions for Control Plane Policing

Information About Control Plane Policing

Benefits of Control Plane Policing

Terms to Understand

Control Plane Security and Packet QoS Overview

Aggregate Control Plane Services

Distributed Control Plane Services

Usage of Distributed CP Services

Output Rate-Limiting and Silent Mode Operation

How to Use Control Plane Policing

Defining Aggregate Control Plane Services

Prerequisites

Restrictions

Defining Distributed Control Plane Services

Prerequisites

Restrictions

Verifying Aggregate Control Plane Services

Examples

Verifying Distributed Control Plane Services

Examples

Configuration Examples for Control Plane Policing

Example: Configuring Control Plane Policing on Input Telnet Traffic

Example: Configuring Control Plane Policing on Output ICMP Traffic

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Command Reference

Feature Information for Control Plane Policing


Control Plane Policing


First Published: January 19, 2006
Last Updated: July 23, 2010

The Control Plane Policing feature allows you to configure a quality of service (QoS) filter that manages the traffic flow of control plane packets to protect the control plane of Cisco IOS routers and switches against reconnaissance and denial-of-service (DoS) attacks. In this way, the control plane (CP) can help maintain packet forwarding and protocol states despite an attack or heavy traffic load on the router or switch.

Finding Feature Information

Your software release may not support all the features documented in this module. 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 Control Plane Policing" section.

Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS 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

Prerequisites for Control Plane Policing

Restrictions for Control Plane Policing

Information About Control Plane Policing

How to Use Control Plane Policing

Configuration Examples for Control Plane Policing

Additional References

Command Reference

Feature Information for Control Plane Policing

Prerequisites for Control Plane Policing

The Modular Quality of Service (QoS) Command-Line interface (CLI) (MQC) is used to configure the packet classification and policing functionality of the Control Plane Policing feature.

Before configuring Control Plane Policing (CoPP), you should understand the procedures for using the MQC. For information about the MQC, see the "Applying QoS Features Using the MQC" module.

Restrictions for Control Plane Policing

Aggregate and Distributed Control Plane Policing

Aggregate policing is supported in Cisco IOS Release 12.0(29)S, Cisco IOS Release 12.2(18)S, Cisco IOS Release 12.3(4)T, and later releases.

Distributed policing is supported only in Cisco IOS Release 12.0(30)S and later Cisco IOS 12.0S releases.

Output Rate-Limiting Support

Output rate-limiting is performed in silent (packet discard) mode. Silent mode enables a router to silently discard packets using policy maps applied to output control plane traffic with the service-policy output command. For more information, see the "Output Rate-Limiting and Silent Mode Operation" section.

Output rate-limiting (policing) in silent mode is supported only in:

Cisco IOS Release 12.2(25)S and later Cisco IOS 12.2S releases

Cisco IOS Release 12.3(4)T and later Cisco IOS 12.3T releases

Output rate-limiting is not supported for distributed control plane services in Cisco IOS 12.0S releases or in Cisco IOS 12.2SX releases.

Output rate-limiting is not supported on the Cisco 7500 series and Cisco 10720 Internet router.

MQC Restrictions

The Control Plane Policing feature requires the MQC to configure packet classification and policing. All restrictions that apply when you use the MQC to configure policing also apply when you configure control plane policing. Only two MQC actions are supported in policy maps—police and drop.


Note On the Cisco 10720 Internet router, only the police command, not the drop command, is supported in policy maps. In addition, in a QoS service policy that is attached to the Cisco 10720 control plane, the police command does not support set actions as arguments in conform-action, exceed-action, and violate-action parameters.


Features that require Network-Based Application Recognition (NBAR) classification may not work well at the control plane level. The following classification (match) criteria are supported on all platforms:

Standard and extended IP access lists (ACLs).

In class-map configuration mode: match ip dscp, match ip precedence, and match protocol arp, and match protocol pppoe commands.


Note In the Cisco IOS 12.2SX release, the match protocol arp command is not supported.


On the Cisco 10720 Internet router, the following MQC commands are also supported in class-map configuration mode: match input-interface, match mpls experimental, match protocol ipv6, and match qos-group. When using these commands for control plane policing on the Cisco 10720 Internet router, note the following restrictions:

Packet classification using match criteria is not supported for packets that cannot be classified in the Cisco 10720 data path, such as unknown Layer 2 encapsulation and IP options.

The following IPv6 fields are not be supported in packet classification for IPv6 QoS on the Cisco 10720 Internet router and are, therefore, not supported for control plane policing:

IPv6 source and destination addresses

Layer 2 class of service (CoS)

IPv6 routing header flag

IPv6 undetermined transport flag

IPv6 flow label

IP Real-Time transport Protocol (RTP)


Note Packets that are not supported for QoS packet classification on the Cisco 10720 Internet router are not policed in the default traffic class for control plane policing.


CISCO-CLASS-BASED-QOS-MIB Control Plane Support

In Cisco IOS Release 12.3(7)T and later Cisco IOS 12.3T releases, the CISCO-CLASS-BASED-QOS-MIB is extended to manage control plane QoS policies and provide information about the control plane.

Cisco IOS Release 12.2(18)SXD1

In Cisco IOS Release 12.2(18)SXD1 and later releases, Hardware Control Plane Interface for Control Plane Policing has the following restrictions:

Supported only with Supervisor Engine 720. Not supported with Supervisor Engine 2.

Does not support CoPP output rate-limiting (policing).

Does not support the CoPP silent operation mode.

Cisco IOS Release 12.2(18)SXD1 and later releases automatically install the CoPP service policy on all DFC-equipped switching modules.

For more information about control plane policing in Cisco IOS Release 12.2(18)SXD1 and later releases, see either of these publications:

For Catalyst 6500 series switches, see the "Configuring Control Plane Policing (CoPP)" module.

For Cisco 7600 series routers, see the "Configuring Denial of Service Protection" module.

Information About Control Plane Policing

To configure the Control Plane Policing feature, you should understand the following concepts:

Benefits of Control Plane Policing

Terms to Understand

Control Plane Security and Packet QoS Overview

Aggregate Control Plane Services

Distributed Control Plane Services

Usage of Distributed CP Services

Output Rate-Limiting and Silent Mode Operation

Benefits of Control Plane Policing

Configuring the Control Plane Policing feature on your Cisco router or switch provides the following benefits:

Protection against DoS attacks at infrastructure routers and switches

QoS control for packets that are destined to the control plane of Cisco routers or switches

Ease of configuration for control plane policies

Better platform reliability and availability

Terms to Understand

Because different platforms can have different architectures, the following set of terms is defined. Figure 1 illustrates how control plane policing works.

Figure 1 Layout of Control Plane, Central Switch Engine, Distributed Switch Engines, and Line Cards on a Router


Control plane (CP)—A collection of processes that run at the process level on the route processor (RP). These processes collectively provide high-level control for most Cisco IOS functions.

Central switch engine—A device that is responsible for high-speed routing of IP packets. It also typically performs high-speed input and output services for nondistributed interfaces. (See nondistributed line cards.) The central switch engine is used to implement aggregate CP protection for all interfaces on the router.


Note All IP packets that are destined for the CP should pass through the central switch engine before they are forwarded to the process level.


On the Cisco 10720 Internet router, control plane policing is implemented on Cisco Parallel eXpress Forwarding (PXF) in a Toaster-based architecture. PXF is a hardware-based central switch engine that can filter traffic at a higher rate than the route processor. PXF switches all data traffic separately from the route processor. PXF packet processing occurs at an intermediate step between the nondistributed line cards and the route processor shown in Figure 1. In addition to the regular punting, PXF also punts certain types of packets (such as unknown Layer 2 encapsulation and packets with IP options) to the RP for further processing at interrupt level.


Note On the Cisco 10720 Internet router, you can configure enhanced RP protection by using the ip option drop command to drop IPv4 packets with IP options that are punted to the RP by PXF. Tunneled IPv4 packets and IPv4 packets with an unsupported encapsulation method are not dropped. For more information, see the "ACL IP Options Selective Drop" module.


Distributed switch engine—A device that is responsible for high-speed switching of IP packets on distributed line cards without using resources from the central switch engine. It also typically performs input and output services for the line card. Each distributed switch engine is used to implement distributed CP services for all ports on a line card. Input CP services distribute the processing load across multiple line cards and conserve vital central switch engine resources. Distributed CP services are optional; however, they provide a more refined level of service than aggregate services.

Nondistributed line cards—Line cards that are responsible for receiving packets and occasionally performing input and output services. All packets must be forwarded to the central switch engine for a routing or switching decision. Aggregate CP services provide coverage for nondistributed line cards.


Note Distributed CP services are supported only in Cisco IOS Release 12.0(30)S and later 12.0S releases.


Control Plane Security and Packet QoS Overview

To protect the CP on a router from DoS attacks and to provide packet QoS, the Control Plane Policing feature treats the CP as a separate entity with its own ingress (input) and egress (output) ports, which are like ports on a router and switch. Because the Control Plane Policing feature treats the CP as a separate entity, a set of rules can be established and associated with the ingress and egress ports of the CP.

These rules are applied only after the packet has been determined to have the CP as its destination or when a packet exits the CP. Thereafter, you can configure a service policy to prevent unwanted packets from progressing after a specified rate limit has been reached; for example, a system administrator can limit all TCP/SYN packets that are destined for the CP to a maximum rate of 1 megabit per second.

Input CP services are executed after router input port services have been performed and after a routing decision on the input path has been made. As shown in Figure 2, CP security and packet QoS are applied on:

An aggregate level by the central switch engine and applied to all CP packets received from all line cards on the router (see the "Aggregate Control Plane Services" section).

A distributed level by the distributed switch engine of a line card and applied to all CP packets received from all interfaces on the line card (see the "Distributed Control Plane Services" section).

Figure 2 Input Control Plane Services: Aggregate and Distributed Services

The following types of Layer 3 packets are forwarded to the control plane and processed by aggregate and distributed control plane policing:

Routing protocol control packets

Packets destined for the local IP address of the router

Packets from management protocols (such as Simple Network Management Protocol [SNMP], Telnet, and secure shell [SSH])


Note Ensure that Layer 3 control packets have priority over other packet types that are destined for the control plane.


Aggregate Control Plane Services

Aggregate control plane services provide control plane policing for all CP packets that are received from all line-card interfaces on the router.

The central switch engine executes normal input port services and makes routing decisions for an incoming packet: if the packet is destined for the CP, aggregate services are performed. Because CP traffic from all line cards must pass through aggregate CP services, these services manage the cumulative amount of CP traffic that reaches the CP.

Aggregate CP service steps are as follows:

1. The line card receives a packet and delivers it to the central switch engine.


Note Before the packet is sent to the central switch engine, additional processing may be necessary for platforms that support hardware-level policing or platform-specific aggregate policing. It is possible that the packet may undergo multiple checks before it undergoes the generic Cisco IOS check.


2. The interfaces perform normal (interface-level) input port services and QoS.

3. The central switch engine performs Layer 3 switching or makes a routing decision, determining whether or not the packet is destined for the CP.

4. The central switch engine performs aggregate CP services for all CP packets.

5. On the basis of the results of the aggregate CP services, the central switch engine either drops the packet or delivers the packet to the CP for final processing.

Functionality Highlights of Aggregate CP Services

The following list highlights the functionality of aggregate CP services:

Aggregate CP services are defined for a single input interface, such as the CP, and represent an aggregate for all ports on a router.

Modular QoS is used to define CP services. Class maps and policy maps for both DoS protection and packet QoS are defined for a single aggregate CP service policy.

Modular QoS does not prevent a single bad port from consuming all allocated bandwidth. Class maps that match an interface or subinterface may be able to constrain the contribution of each interface through an interface-specific policy map.

Distributed Control Plane Services

Distributed control plane services provide control plane policing for all CP packets that are received from the interfaces on a line card.

A distributed switch engine executes normal input port services and makes routing decisions for a packet: if the packet is destined for the CP, distributed CP services are performed. Afterwards, CP traffic from each line card is forwarded to the central switch engine where aggregate CP services are applied.


Note Distributed CP services may also forward conditioned packets to the central switch engine. In this case, aggregate CP services are also performed on the conditioned CP traffic.


Distributed CP service steps are as follows:

1. A line card receives a packet and delivers it to the distributed switch engine.

2. The distributed switch engine performs normal (interface-level) input port services and QoS.

3. The distributed switch engine performs Layer 2 or Layer 3 switching or makes a routing decision, determining whether the packet is destined for the CP.

4. The distributed switch engine performs distributed CP services for all CP packets.

5. On the basis of the results of the distributed CP services, the distributed switch engine either drops the packet or marks the packet and delivers it to the central switch engine for further processing.

6. The central switch engine performs aggregate CP services and delivers the packet to the CP for final processing.

Functionality Highlights of Distributed CP Services

The following list highlights the functionality of distributed CP services:

Distributed CP services are defined for a single input interface, such as the distributed CP, and represent an aggregate for all ports on a line card.

The MQC is used to define CP services. Class maps and policy maps for both DoS protection and packet QoS are defined for a single distributed CP service policy. Each line card may have a unique CP service policy that applies traffic classifications, QoS policies, and DoS services to packets received from all ports on the line card in an aggregate way.

The MQC does not prevent one bad port from consuming all allocated bandwidth on a line card. Class maps that match an interface or subinterface may be able to constrain the contribution of each interface through an interface-specific policy map.

Distributed CP services allow you to limit the number of CP packets forwarded from a line card to the central switch engine. The total number of CP packets received from all line cards on a router may exceed aggregate CP levels.

Usage of Distributed CP Services

The purpose of CP protection and packet QoS is to apply sufficient control to the packets that reach the control plane. To successfully configure this level of CP protection, you must:

Apply traditional QoS services using the MQC to CP packets.

Protect the path to the control plane against indiscriminate packet dropping due to resource exhaustion. If packets are not dropped according to user-defined QoS policies, but are dropped due to a resource limitation, the QoS policy is not maintained.

Distributed CP services allow you to configure specific CP services that are enforced at the line-card level and are required for the following reasons:

While under a DoS attack, line-card resources may be consumed. In this case, you must configure a drop policy to identify important packets. The drop policy ensures that all important packets arrive to the central switch engine for aggregate CP protection and arrive later to the CP. Distributed CP services allow routers to apply the appropriate drop policy when resources are consumed and therefore maintain the desired QoS priorities. If a line card indiscriminately drops packets, the aggregate CP filter becomes ineffective and the QoS priorities are no longer maintained.

It is not possible to prevent one interface from consuming all aggregate CP resources. A DoS attack on one port may negatively impact CP processing of traffic from other ports. Distributed CP services allow you to limit the amount of important traffic that is forwarded by a line card to the CP. For example, you can configure a layered approach in which the combined rates of all line cards are over-subscribed compared to the aggregate rate. The rate of each individual line card would be below the aggregate rate, but combined together, the rates of all line cards exceed it. This over-subscription model is commonly used for other resource-related functions and helps limit the contribution of CP packets from any one line card.

Distributed CP services provide for slot-level (line-card) filtering. Customer-facing interfaces may have greater security requirements (with more restrictions or for billing reasons) than network-facing interfaces to backbone devices.

Because distributed CP protection allows you to configure packet filters on a per-line-card basis, processing cycles on line cards may offload aggregate level processing. You can configure Border Gateway Protocol (BGP) filtering at the distributed level for interfaces that use BGP, allowing the aggregate level to filter packets with the remaining filter requirements. Or you can configure identical filters for distributed and aggregate CP services with a distributed packet marking scheme that informs the aggregate filter that a packet has already been checked. Distributed CP service processing further reduces aggregate processing and can significantly reduce the load on aggregate CP services.

Output Rate-Limiting and Silent Mode Operation

A router is automatically enabled to silently discard packets when you configure output policing on control plane traffic using the service-policy output policy-map-name command.

Rate-limiting (policing) of output traffic from the CP is performed in silent mode. In silent mode, a router that is running Cisco IOS software operates without sending any system messages. If a packet that is exiting the control plane is discarded for output policing, you do not receive an error message.

When control plane policing is configured for output traffic, error messages are not generated in the following cases:

Traffic that is being transmitted to a port to which the router is not listening

A connection to a legitimate address and port that is rejected because of a malformed request


Note The silent mode functionality and output policing on CP traffic are supported only in:

Cisco IOS Release 12.2(25)S and later Cisco IOS 12.2S releases

Cisco IOS Release 12.3(4)T and later Cisco IOS 12.3T releases

Silent mode and output policing on CP traffic are not supported for distributed control plane services.


How to Use Control Plane Policing

This section documents the following procedures:

Defining Aggregate Control Plane Services (required)

Defining Distributed Control Plane Services (required)

Verifying Aggregate Control Plane Services (optional)

Verifying Distributed Control Plane Services (optional)

Defining Aggregate Control Plane Services

To configure aggregate CP services, such as packet rate control and silent packet discard, for the active route processor, complete the following steps.

Prerequisites

Before you enter control-plane configuration mode to attach an existing QoS policy to the control plane, you must first create the policy using MQC to define a class map and policy map for control plane traffic.

Restrictions

Platform-specific restrictions, if any, are checked when the service policy is applied to the control plane interface.

Support for output policing is available only in Cisco IOS Release 12.3(4)T and later T-train releases. (Note that output policing does not provide any performance benefits. It simply controls the information that is leaving the device.)

SUMMARY STEPS

1. enable

2. configure terminal

3. control-plane

4. service-policy {input | output} policy-map-name

5. end

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

control-plane

Example:

Router(config)# control-plane

Enters control-plane configuration mode (a prerequisite for Step 4).

Step 4 

service-policy {input | output} policy-map-name

Example:

Router(config-cp)# service-policy input control-plane-policy

Attaches a QoS service policy to the control plane. Note the following points:

input—Applies the specified service policy to packets received on the control plane.

output—Applies the specified service policy to packets transmitted from the control plane and enables the router to silently discard packets.

policy-map-name—Name of a service policy map (created using the policy-map command) to be attached. The name can be a maximum of 40 alphanumeric characters.

Step 5 

end

Example:

Router(config-cp)# end

(Optional) Returns to privileged EXEC mode.

Defining Distributed Control Plane Services

To configure distributed CP services, such as packet rate control, for packets that are destined for the CP and sent from the interfaces on a line card, complete the following steps.

Prerequisites

Before you enter control-plane configuration mode to attach an existing QoS policy for performing distributed control-plane services, you must first create the policy using MQC to define a class map and policy map for control-plane traffic.

Restrictions

Platform-specific restrictions, if any, are checked when the service policy is applied to the control plane interface.

Support for output policing is available only in Cisco IOS Release 12.3(4)T and later T-train releases. (Note that output policing does not provide any performance benefits. It simply controls the information that is leaving the device.)

With Cisco IOS 12.2SX releases, the Supervisor Engine 720 automatically installs the service policy on all DFC-equipped switching modules.

SUMMARY STEPS

1. enable

2. configure terminal

3. control-plane [slot slot-number]

4. service-policy input policy-map-name

5. end

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

control-plane [slot slot-number]

Example:

Router(config)# control-plane slot 3

Enters control-plane configuration mode, which allows you to optionally attach a QoS policy (used to manage CP traffic) to the specified slot.

Enter the slot keyword and the slot number, as applicable.

Step 4 

service-policy input policy-map-name

Example:

Router(config-cp)# service-policy input control-plane-policy

Attaches a QoS policy map to filter and manage CP traffic on a specified line card before the aggregate CP policy is applied. Note the following points:

input—Applies the specified policy map using the distributed switch engine to CP packets that are received from all interfaces on the line card.

policy-map-name—Name of a service policy map (created using the policy-map command) to be attached. The name can be a maximum of 40 alphanumeric characters.

Note The service-policy output policy-map-name command is not supported for applying a QoS policy map for distributed control plane services.

Step 5 

end

Example:

Router(config-cp)# end

(Optional) Returns to privileged EXEC mode.

Verifying Aggregate Control Plane Services

To display information about the service policy attached to the control plane for aggregate CP services, complete the following steps.

SUMMARY STEPS

1. enable

2. show policy-map control-plane [all] [input [class class-name] | output [class class-name]]

3. exit

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2 

show policy-map control-plane [all] [input [class class-name] | output [class class-name]]

Example:

Router# show policy-map control-plane all

Displays information about the control plane. Note the following points:

all—(Optional) Service policy information about all QoS policies used in aggregate and distributed CP services.

input—(Optional) Statistics for the attached input policy.

output—(Optional) Statistics for the attached output policy.

class class-name—(Optional) Name of the traffic class whose configuration and statistics are displayed.

Step 3 

exit

Example:

Router(config-cp)# exit

(Optional) Exits privileged EXEC mode.

Examples

The following example shows that the policy map TEST is associated with the control plane. This policy map polices traffic that matches the class map TEST, while allowing all other traffic (that matches the class map "class-default") to go through as is.

Router# show policy-map control-plane 

Control Plane 

Service-policy input:TEST

Class-map:TEST (match-all)
      20 packets, 11280 bytes
      5 minute offered rate 0 bps, drop rate 0 bps
      Match:access-group 101
      police:
        8000 bps, 1500 limit, 1500 extended limit
        conformed 15 packets, 6210 bytes; action:transmit
        exceeded 5 packets, 5070 bytes; action:drop
        violated 0 packets, 0 bytes; action:drop
        conformed 0 bps, exceed 0 bps, violate 0 bps

Class-map:class-default (match-any)
      105325 packets, 11415151 bytes
      5 minute offered rate 0 bps, drop rate 0 bps
      Match:any 

Verifying Distributed Control Plane Services

To display information about the service policy attached to the control plane to perform distributed CP services, complete the following steps.

SUMMARY STEPS

1. enable

2. show policy-map control-plane [all | slot slot-number] [input [class class-name] | output [class class-name]]

3. exit

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2 

show policy-map control-plane [all][slot slot-number] [input [class class-name] | output [class class-name]]

Example:

Router# show policy-map control-plane slot 2

Displays information about the service policy used to apply distributed CP services on the router. Note the following points:

all—(Optional) Service policy information about all QoS policies used in aggregate and distributed CP services.

slot slot-number—(Optional) Service policy information about the QoS policy map used to perform distributed CP services on the specified line card.

input—(Optional) Statistics for the attached input policy map.

output—(Optional) Statistics for the attached output policy map.

class class-name—(Optional) Name of the traffic class whose configuration and statistics are displayed.

Step 3 

exit

Example:

Router# exit

(Optional) Exits privileged EXEC mode.

Examples

The following example shows how to display information about the classes of CP traffic received from all interfaces on the line card in slot 1 to which the policy map TESTII is applied for distributed CP services. This policy map polices traffic that matches the traffic class TESTII, while allowing all other traffic (that matches the class map "class-default") to go through as is.

Router# show policy-map control-plane slot 1

Control Plane - slot 1

Service-policy input: TESTII (1048)

Class-map: TESTII (match-all) (1049/4)
        0 packets, 0 bytes
        5 minute offered rate 0 bps, drop rate 0 bps
        Match: protocol arp (1050)
        police:
            cir 8000 bps, bc 4470 bytes, be 4470 bytes
          conformed 0 packets, 0 bytes; actions:
            transmit
          exceeded 0 packets, 0 bytes; actions:
            drop
          violated 0 packets, 0 bytes; actions:
            drop
          conformed 0 bps, exceed 0 bps, violate 0 bps

Class-map: class-default (match-any) (1052/0)
        0 packets, 0 bytes
        5 minute offered rate 0 bps, drop rate 0 bps
        Match: any  (1053)

Configuration Examples for Control Plane Policing

This section contains examples that shows how to configure aggregate control plane services on both an input and an output interface:

Example: Configuring Control Plane Policing on Input Telnet Traffic

Example: Configuring Control Plane Policing on Output ICMP Traffic

Example: Configuring Control Plane Policing on Input Telnet Traffic

The following example shows how to apply a QoS policy for aggregate CP services to Telnet traffic that is received on the control plane. Trusted hosts with source addresses 10.1.1.1 and 10.1.1.2 forward Telnet packets to the control plane without constraint, while allowing all remaining Telnet packets to be policed at the specified rate.

! Allow 10.1.1.1 trusted host traffic.
Router(config)# access-list 140 deny tcp host 10.1.1.1 any eq telnet 
! Allow 10.1.1.2 trusted host traffic. 
Router(config)# access-list 140 deny tcp host 10.1.1.2 any eq telnet 
! Rate-limit all other Telnet traffic.
Router(config)# access-list 140 permit tcp any any eq telnet
! Define class-map "telnet-class."
Router(config)# class-map telnet-class 
Router(config-cmap)# match access-group 140
Router(config-cmap)# exit
Router(config)# policy-map control-plane-in
Router(config-pmap)# class telnet-class
Router(config-pmap-c)# police 80000 conform transmit exceed drop
Router(config-pmap-c)# exit
Router(config-pmap)# exit
! Define aggregate control plane service for the active route processor.
Router(config)# control-plane
Router(config-cp)# service-policy input control-plane-in
Router(config-cp)# end

Example: Configuring Control Plane Policing on Output ICMP Traffic

The following example shows how to apply a QoS policy for aggregate CP services to Telnet traffic transmitted from the control plane. Trusted networks with source addresses 10.0.0.0 and 10.0.0.1 receive Internet Control Management Protocol (ICMP) port-unreachable responses without constraint, while allowing all remaining ICMP port-unreachable responses to be dropped:

! Allow 10.0.0.0 trusted network traffic.
Router(config)# access-list 141 deny icmp 10.0.0.0 0.0.0.255 any port-unreachable 
! Allow 10.0.0.1 trusted network traffic.
Router(config)# access-list 141 deny icmp 10.0.0.1 0.0.0.255 any port-unreachable 
! Rate-limit all other ICMP traffic. 
Router(config)# access-list 141 permit icmp any any port-unreachable
Router(config)# class-map icmp-class 
Router(config-cmap)# match access-group 141
Router(config-cmap)# exit
Router(config)# policy-map control-plane-out
! Drop all traffic that matches the class "icmp-class."
Router(config-pmap)# class icmp-class
Router(config-pmap-c)# drop
Router(config-pmap-c)# exit
Router(config-pmap)# exit
Router(config)# control-plane
! Define aggregate control plane service for the active route processor.
Router(config-cp)# service-policy output control-plane-out
Router(config-cp)# end

Additional References

The following sections provide references related to the Control Plane Policing feature.

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Related Topic
Document Title

QoS commands: complete command syntax, command modes, command history, defaults, usage guidelines, and examples

Cisco IOS Quality of Service Solutions Command Reference

QoS features overview

"Quality of Service Overview" module

MQC

"Applying QoS Features Using the MQC" module

Security features overview

"Control Plane Security Overview" module in the Cisco IOS Security Configuration Guide: Securing the Control Plane

Control plane policing in Cisco IOS Release 12.2(18)SXD1 and later releases

For Catalyst 6500 series switches, see the "Configuring Control Plane Policing (CoPP)" module.

For Cisco 7600 series routers, see the "Configuring Denial of Service Protection" module.

Enhanced RP protection

"ACL IP Options Selective Drop" module


Standards

Standard
Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.


MIBs

MIB
MIBs Link

CISCO-CLASS-BASED-QOS-MIB

Note Supported only in Cisco IOS Release 12.3(7)T.

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator, found at the following URL:

http://www.cisco.com/go/mibs


RFCs

RFC
Title

No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature.


Technical Assistance

Description
Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

http://www.cisco.com/cisco/web/support/index.html


Command Reference

The following commands are introduced or modified in the feature or features documented in this module. For information about these commands, see the Cisco IOS Quality of Service Solutions Command Reference at http://www.cisco.com/en/US/docs/ios/qos/command/reference/qos_book.html. For information about all Cisco IOS commands, use the Command Lookup Tool at http://tools.cisco.com/Support/CLILookup or the Cisco IOS Master Command List, All Releases, at http://www.cisco.com/en/US/docs/ios/mcl/allreleasemcl/all_book.html.

control-plane

service-policy (control-plane)

show policy-map control-plane

Feature Information for Control Plane Policing

Table 1 lists the release history for this feature.

Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS, Catalyst OS, and 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.


Note Table 1 lists only the Cisco IOS software release that introduced support for a given feature in a given Cisco IOS software release train. Unless noted otherwise, subsequent releases of that Cisco IOS software release train also support that feature.


Table 1 Feature Information for Control Plane Policing

Feature Name
Releases
Feature Information

Control Plane Policing

12.2(18)S
12.3(4)T
12.3(7)T
12.0(29)S
12.2(18)SXD1
12.0(30)S
12.2(27)SBC
12.0(32)S
12.3(31)SB2
15.0(1)S

The Control Plane Policing feature allows users to configure a quality of service (QoS) filter that manages the traffic flow of control plane packets to protect the control plane of Cisco IOS routers and switches against reconnaissance and denial-of-service (DoS) attacks.

For Release 12.2(18)S, this feature was introduced.

For Release 12.3(4)T, this feature was integrated into Cisco IOS Release 12.3(4)T, and the output rate-limiting (silent mode operation) feature was added.

For Release 12.3(7)T, the CISCO-CLASS-BASED-QOS-MIB was extended to manage control plane QoS policies, and the police rate command was introduced to support traffic policing on the basis of packets per second for control plane traffic.

For Release 12.0(29)S, this feature was integrated into Cisco IOS Release 12.0(29)S.

For Release 12.2(18)SXD1, this feature was integrated into Cisco IOS Release 12.2(18)SXD1.

For Release 12.0(30)S, this feature was modified to include support for distributed control plane services on the Cisco 12000 series Internet router.

For Release 12.2(27)SBC, this feature was integrated into Cisco IOS Release 12.2(27)SBC.

For Release 12.0(32)S, this feature was modified to include support for aggregate control plane services on the Cisco 10720 Internet router.

For Release 12.3(31)SB2, this feature was implemented on the Cisco 10000 series router for the PRE3.

For Release 15.0(1)S, this feature was integrated into Cisco IOS Release 15.0(1)S.