IPv4 ACL Chaining Support

ACL Chaining, also known as Multi-Access Control List, allows you to split access control lists (ACLs). This module describes how with the IPv4 ACL Chaining Support feature, you can explicitly split ACLs into common and user-specific ACLs and bind both ACLs to a target for traffic filtering on a device. In this way, the common ACLs in Ternary Content Addressable Memory (TCAM) are shared by multiple targets, thereby reducing the resource usage.

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 Table at the end of this document.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http:/​/​tools.cisco.com/​ITDIT/​CFN/​. An account on http:/​/​www.cisco.com/​ is not required.

Contents

Hardware Compatibility Matrix for Cisco cBR Series Routers


Note

The hardware components introduced in a given Cisco IOS-XE Release are supported in all subsequent releases unless otherwise specified.

Table 1 Hardware Compatibility Matrix for the Cisco cBR Series Routers

Cisco CMTS Platform

Processor Engine

Interface Cards

Cisco cBR-8 Converged Broadband Router

Cisco IOS-XE Release 3.15.0S and Later Releases

Cisco cBR-8 Supervisor:

  • PID—CBR-CCAP-SUP-160G

  • PID—CBR-CCAP-SUP-60G1

  • PID—CBR-SUP-8X10G-PIC

Cisco IOS-XE Release 3.15.0S and Later Releases

Cisco cBR-8 CCAP Line Cards:

  • PID—CBR-LC-8D30-16U30

  • PID—CBR-LC-8D31-16U30

  • PID—CBR-RF-PIC

  • PID—CBR-RF-PROT-PIC

Cisco cBR-8 Downstream PHY Modules:

  • PID—CBR-D30-DS-MOD

  • PID—CBR-D31-DS-MOD

Cisco cBR-8 Upstream PHY Modules:

  • PID—CBR-D30-US-MOD

1 Effective with Cisco IOS-XE Release 3.17.0S, CBR-CCAP-SUP-60G supports 8 cable line cards. The total traffic rate is limited to 60Gbps, the total number of downstream service flow is limited to 72268, and downstream unicast low-latency flow does not count against the limits.

Restrictions for IPv4 ACL Chaining Support

  • A single access control List (ACL) cannot be used for both common and regular ACLs for the same target in the same direction.

  • ACL chaining applies to only security ACLs. It is not supported for feature policies, such as Quality of Service (QoS), Firewall Services Module (FW) and Policy Based Routing (PBR).

  • Per-target statistics are not supported for common ACLs.

Information About IPv4 ACL Chaining Support

ACL Chaining Overview

The packet filter process supports only a single Access control list (ACL) to be applied per direction and per protocol on an interface. This leads to manageability and scalability issues if there are common ACL entries needed on many interfaces. Duplicate Access control entries (ACEs) are configured for all those interfaces, and any modification to the common ACEs needs to be performed for all ACLs.

A typical ACL on the edge box for an Internet Service Provider (ISP) has two sets of ACEs:

  • Common ISP specific ACEs

  • Customer/interface specific ACEs

The purpose of these address blocks is to deny access to ISP's protected infrastructure networks and anti-spoofing protection by allowing only customer source address blocks. This results in configuring unique ACL per interface and most of the ACEs being common across all ACLs on a device. ACL provisioning and modification is very cumbersome, hence, any changes to the ACE impacts every target.

IPv4 ACL Chaining Support

IPv4 ACL Chaining Support allows you to split the Access control list (ACL) into common and customer-specific ACLs and attach both ACLs to a common session. In this way, only one copy of the common ACL is attached to Ternary Content Addressable Memory (TCAM) and shared by all users, thereby making it easier to maintain the common ACEs.

The IPv4 ACL Chaining feature allows two IPV4 ACLs to be active on an interface per direction:

  • Common

  • Regular

  • Common and Regular


Note
If you configure both common and regular ACLs on an interface, the common ACL is considered over a regular ACL.

How to Configure IPv4 ACL Chaining Support

ACL chaining is supported by extending the ip traffic filter command.

The ip traffic filter command is not additive. When you use this command, it replaces earlier instances of the command.

For more information, refer to the IPv6 ACL Chaining with a Common ACL section in the Security Configuration Guide: Access Control Lists Configuration Guide.

Configuring an Interface to Accept Common ACL

Perform this task to configure the interface to accept a common Access control list (ACL) along with an interface-specific ACL:

Procedure
     Command or ActionPurpose
    Step 1 enable


    Example: 
    Device> enable
     

    Enables privileged EXEC mode. Enter your password if prompted.

     
    Step 2 configure terminal


    Example: 
    Device# configure terminal
     

    Enters global configuration mode.

     
    Step 3 interface type number


    Example: 
    Device(config)# interface TenGigabitEthernet4/1/0
     

    Configures an interface and enters the interface configuration mode.

     
    Step 4 ip access-group {common {common-access-list-name {regular-access-list | acl}}{in | out}}


    Example: 
    Device(config-if)# ipv4 access-group common acl-p acl1 in
     

    Configures the interface to accept a common ACL along with the interface-specific ACL.

     
    Step 5 end


    Example: 
    Device(config-if)# end
     

    (Optional) Exits the configuration mode and returns to privileged EXEC mode.

     

    Configuration Examples for IPv4 ACL Chaining Support

    This section provides configuration examples of Common Access Control List (ACL).

    Example: Configuring an Interface to Accept a Common ACL

    This example shows how to replace an Access Control List (ACL) configured on the interface without explicitly deleting the ACL: 

    interface TenGigabitEthernet4/1/0
ipv4 access-group common  C_acl ACL1 in
end
replace interface acl ACL1 by ACL2
interface TenGigabitEthernet4/1/0
ipv4 access-group common  C_acl ACL2 in
end

    This example shows how common ACL cannot be replaced on interfaces without deleting it explicitly from the interface: 

    interface TenGigabitEthernet4/1/0
ipv4 access-group common  C_acl1 ACL1 in
end
change the common acl to C_acl2
interface TenGigabitEthernet4/1/0
no ipv4 access-group common  C_acl1  ACL1 in
end
interface TenGigabitEthernet4/1/0
ipv4 access-group common  C_acl2  ACL1 in
end

    Note
    When reconfiguring a common ACL, you must ensure that no other interface on the line card is attached to the common ACL.

    Note
    If both common ACL and interface ACL are attached to an interface and only one of the above is reconfigured on the interface, then the other is removed automatically.

    This example shows how the interface ACL is removed: 

    interface TenGigabitEthernet4/1/0
ipv4 access-group common C_acl1 ACL1 in
end

    Additional References for IPv4 ACL Chaining Support

    Related Documents

    Related Topic Document Title

    IPv6 ACL Chaining Support

    Security Configuration Guide: Access Control Lists, Cisco IOS XE Release 3S

    Cisco IOS commands

    Cisco IOS Master Command List, All Releases

    Security commands

    Technical Assistance

    Description Link

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    http:/​/​www.cisco.com/​support

    Feature Information for IPv4 ACL Chaining Support

    Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http:/​/​tools.cisco.com/​ITDIT/​CFN/​. An account on http:/​/​www.cisco.com/​ is not required.


    Note

    The below table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

    Table 2 Feature Information for IPv4 ACL Chaining Support

    Feature Name

    Releases

    Feature Information

    IP Access Lists

    Cisco IOS-XE Release 3.15.0S

    This feature was introduced on the Cisco cBR Series Converged Broadband Routers.