Layer 2 Access Control Lists on EVCs

Last Updated: October 2, 2011

The ability to filter packets in a modular and scalable way is important for both network security and network management. Access Control Lists (ACLs) provide the capability to filter packets at a fine granularity. In Metro Ethernet networks, ACLs are directly applied on Ethernet virtual circuits (EVCs).

Layer 2 Access Control Lists on EVCs is a security feature that allows packet filtering based on MAC addresses. This module describes how to implement ACLs on EVCs.

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 www.cisco.com/go/cfn. An account on Cisco.com is not required.

Prerequisites for Layer 2 Access Control Lists on EVCs

  • Knowledge of how service instances must be configured.
  • Knowledge of extended MAC ACLs and how they must be configured.

Restrictions for Layer 2 Access Control Lists on EVCs

  • A maximum of 16 access control entries (ACEs) are allowed for a given ACL.
  • Only 256 different or unique Layer 2 ACLs can be configured on a line card. (More than 256 ACLs can be configured on a router.)
  • Layer 2 ACLs function inbound only.
  • Current Layer 2 ACLs provide Layer 3 filtering options in permit and deny rules. Options that are not relevant to service instances are ignored.

Information About Layer 2 Access Control Lists on EVCs

EVC

An EVC as defined by the Metro Ethernet Forum is a port-level point-to-point or multipoint-to-multipoint Layer 2 circuit. It is an end-to-end representation of a single instance of a Layer 2 service being offered by a provider to a customer. It embodies the different parameters on which the service is being offered. A service instance is the instantiation of an EVC on a given port on a given router.

Ethernet virtual connection services (EVCS) uses EVCs and service instances to provide Layer 2 switched Ethernet services. The EVC status can be used by a customer edge (CE) device either to find an alternative path in to the service provider network or, in some cases, to revert to a backup path over Ethernet or over another alternative service such as Frame Relay or ATM.

For information about the Metro Ethernet Forum standards, see the Standards table in the Additional References section.

Relationship Between ACLs and Ethernet Infrastructure

The following points capture the relationship between ACLs and Ethernet Infrastructure (EI):

  • ACLs can be directly applied on an EVC using the command-line interface (CLI). An ACL is applied to a service instance, which is the instantiation of an EVC on a given port.
  • One ACL can be applied to more than one service instance at any time.
  • One service instance can have one ACL at most applied to it at any time. If a Layer 2 ACL is applied to a service instance that already has a Layer 2 ACL, the new one replaces the old one.
  • Only named ACLs can be applied to service instances. The command syntax ACLs is retained; the mac access-list extended command is used to create an ACL.
  • The show ethernet service instance command can be used to provide details about ACLs on service instances.

How to Configure Layer 2 Access Control Lists on EVCs

Creating a Layer 2 ACL

Perform this task to create a Layer 2 ACL with a single ACE.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    mac access-list extended name

4.    permit {{src-mac mask | any} {dest-mac mask | any} [protocol [vlan vlan] [cos value]]}


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
mac access-list extended name


Example:

Router(config)# mac access-list extended test-12-acl

 

Defines an extended MAC ACL and enters mac access list control configuration mode.

 
Step 4
permit {{src-mac mask | any} {dest-mac mask | any} [protocol [vlan vlan] [cos value]]}


Example:

Router(config-ext-macl)# permit 00aa.00bb.00cc 0.0.0 any

 

Allows forwarding of Layer 2 traffic if the conditions are matched. Creates an ACE for the ACL.

 

Applying a Layer 2 ACL to a Service Instance

Perform this task to apply a Layer 2 ACL to a service instance. Note that packet filtering takes place only after the ACL has been created and applied to the service instance.

Before You Begin

Before applying an ACL to a service instance, you must create it using the mac access-list extended command. See the "Creating a Layer 2 ACL" section on page 3 .


SUMMARY STEPS

1.    enable

2.    configure terminal

3.    interface type number

4.    service instance id ethernet

5.    encapsulation dot1q vlan-id

6.    mac access-group access-list-name in


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
interface type number


Example:

Router(config)# interface gigabitethernet 1/0/0

 

Specifies the type and location of the interface to configure, where:

  • type --Specifies the type of the interface.
  • number --Specifies the location of the interface.
 
Step 4
service instance id ethernet


Example:

Router(config-if)# service instance 100 ethernet

 

Configures an Ethernet service instance on an interface and enters Ethernet service configuration mode.

 
Step 5
encapsulation dot1q vlan-id


Example:

Router(config-if-srv)# encapsulation dot1q 100

 

Defines the matching criteria to be used in order to map ingress dot1q frames on an interface to the appropriate service instance.

 
Step 6
mac access-group access-list-name in


Example:

Router(config-if-srv)# mac access-group test-12-acl in

 

Applies a MAC ACL to control incoming traffic on the interface.

 

Configuring a Layer 2 ACL with ACEs on a Service Instance

Perform this task to configure the same ACL with three ACEs and stop all other traffic on a service instance.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    mac access-list extended name

4.    permit {src-mac mask | any} {dest-mac mask | any}

5.    permit {src-mac mask | any} {dest-mac mask | any}

6.    permit {src-mac mask | any} {dest-mac mask} | any}

7.    deny any any

8.    exit

9.    interface type number

10.    service instance id ethernet

11.    encapsulation dot1q vlan-id

12.    mac access-group access-list-name in


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
mac access-list extended name


Example:

Router(config)# mac access list extended test-12-acl

 

Defines an extended MAC ACL and enters mac access control list configuration mode.

 
Step 4
permit {src-mac mask | any} {dest-mac mask | any}


Example:

Router(config-ext-macl)# permit 00aa.bbcc.ddea 0.0.0 any

 

Allows forwarding of Layer 2 traffic if the conditions are matched. This creates an ACE for the ACL.

 
Step 5
permit {src-mac mask | any} {dest-mac mask | any}


Example:

Router(config-ext-macl)# permit 00aa.bbcc.ddeb 0.0.0 any

 

Allows forwarding of Layer 2 traffic if the conditions are matched. This creates an ACE for the ACL.

 
Step 6
permit {src-mac mask | any} {dest-mac mask} | any}


Example:

Router(config-ext-macl)# permit 00aa.bbcc.ddec 0.0.0 any

 

Allows forwarding of Layer 2 traffic if the conditions are matched. This creates an ACE for the ACL.

 
Step 7
deny any any


Example:

Router(config-ext-macl)# deny any any

 

Prevents forwarding of Layer 2 traffic except for the allowed ACEs.

 
Step 8
exit


Example:

Router(config-ext-macl)# exit

 

Exits the current command mode and returns the CLI to global configuration mode.

 
Step 9
interface type number


Example:

Router(config)# interface gigabitethernet 1/0/0

 

Specifies the interface.

 
Step 10
service instance id ethernet


Example:

Router(config-if)# service instance 200 ethernet

 

Configures an Ethernet service instance on an interface and enters service instance configuration mode.

 
Step 11
encapsulation dot1q vlan-id


Example:

Router(config-if-srv)# encapsulation dot1q 100

 

Defines the matching criteria to be used to map ingress dot1q frames on an interface to the appropriate service instance.

 
Step 12
mac access-group access-list-name in


Example:

Router(config-if-srv)# mac access-group test-12-acl in

 

Applies a MAC ACL to control incoming traffic on the interface.

 

Verifying the Presence of a Layer 2 ACL on a Service Instance

Perform this task to verify that a Layer 2 ACL is present on an EVC. This verification task can be used after an ACL has been configured to confirm its presence.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    show ethernet service instance id id interface type number detail


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# show ethernet service instance id 100 interface gigabitethernet 3/0/1 detail

 

Enters global configuration mode.

 
Step 3
show ethernet service instance id id interface type number detail


Example:

Router# show ethernet service instance id 100 interface gigabitethernet 3/0/1 detail

 

Displays detailed information about Ethernet customer service instances.

 

Configuration Examples for Layer 2 Access Control Lists on EVCs

Example Applying a Layer 2 ACL to a Service Instance

The following example shows how to apply a Layer 2 ACL called mac-20-acl to a service instance. The ACL has five permitted ACEs and all other traffic is not allowed. 

enable
configure terminal
 mac access-list extended mac-20-acl
 permit 00aa.bbcc.adec 0.0.0 any
 permit 00aa.bbcc.bdec 0.0.0 any
 permit 00aa.bbcc.cdec 0.0.0 any
 permit 00aa.bbcc.edec 0.0.0 any
 permit 00aa.bbcc.fdec 0.0.0 any
 deny any any
 exit
interface gigabitethernet 10/0/0
 service instance 100 ethernet
 encapsulation dot1q 100
 mac access-group mac-20-acl in

Example Applying a Layer 2 ACL to Three Service Instances on the Same Interface

The following example shows how to apply a Layer 2 ACL called mac-07-acl to three service instances on the same interface:

enable
configure terminal
mac access-list extended mac-07-acl
permit 00aa.bbcc.adec 0.0.0 any
permit 00aa.bbcc.bdec 0.0.0 any
permit 00aa.bbcc.cdec 0.0.0 any
deny any any
exit
interface gigabitethernet 10/0/0
service instance 100 ethernet
encapsulation dot1q 100
mac access-group mac-07-acl in
service instance 101 ethernet
encapsulation dot1q 101
mac access-group mac-07-acl in
service instance 102 ethernet
encapsulation dot1q 102
mac access-group mac-07-acl in

Example Creating a Layer 2 ACL with ACEs

The following example shows how to create a Layer 2 ACL called mac-11-acl with two permitted ACEs: 

enable
configure terminal
mac access-list extended mac-11-acl
permit 00aa.00bb.00cc 1a11.0101.11c1 any
permit 00aa.00bb.00cc 1a11.0101.11c2 any

Example Displaying the Details of a Layer 2 ACL on a Service Instance

The following sample output displays the details of a Layer 2 ACL called test-acl on a service instance. 

Router# show ethernet service instance id 100 interface ethernet0/0 detail
Service Instance ID: 100
L2 ACL (inbound): test-acl
Associated Interface: Ethernet0/0
Associated EVC: test
L2protocol drop
CEVlans:
Interface Dot1q Tunnel Ethertype: 0x8100
State: Up
L2 ACL permit count: 10255
L2 ACL deny count: 53

The table below describes the significant fields in the output.

Table 1 show ethernet service instance Field Descriptions

Field

Description

Service Instance ID

Displays the service instance ID.

L2 ACL (inbound):

Displays the ACL name.

Associated Interface:

Displays the interface details of the service instance.

Associated EVC:

Displays the EVC with which the service instance is associated.

CEVlans:

Displays details of the associated VLAN ID.

State:

Displays whether the service instance is in an up or down state.

L2 ACL permit count:

Displays the number of packet frames allowed to pass on the service instance by the ACL.

L2 ACL deny count

Displays the number of packet frames not permitted to pass on the service instance by the ACL.

Additional References

Related Documents

Related Topic

Document Title

Cisco IOS Carrier Ethernet commands: complete command syntax, command mode, command history, defaults, usage guidelines, and examples

Cisco IOS Carrier Ethernet Command Reference

Cisco IOS commands: master list of commands with complete command syntax, command mode, command history, defaults, usage guidelines, and examples

Cisco IOS Master Commands List, All Releases

Standards

Standard

Title

MEF 6.1

Metro Ethernet Services Definitions Phase 2 (PDF 6/08)

MEF 10.1

Ethernet Services Attributes Phase 2 (PDF 10/06)

MIBs

MIB

MIBs Link

  • None

To locate and download MIBs for selected platforms, Cisco software 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 release.

--

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

Feature Information for Layer 2 Access Control Lists on EVCs

The following table provides release information about the feature or features described in this module. This 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.

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

Table 2 Feature Information for Layer 2 Access Control Lists on EVCs

Feature Name

Releases

Feature Information

Layer 2 Access Control Lists on EVCs

12.2(33)SRD 15.0(1)S

The Layer 2 Access Control Lists on EVCs feature introduces ACLs on EVCs.

  • The following commands were introduced or modified: interface, mac access-group in, mac access-list extended, show ethernet service instance.

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Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.

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