Security - Configuring Port ACLs and VLAN ACLs  [Support] (2024)

Table Of Contents

Configuring Port ACLs and VLAN ACLs

Understanding ACLs

Understanding ACLs

Understanding VACLs

Understanding Port ACLs

EtherChannel and PACL Interactions

Dynamic ACLs (Applies to Merge Mode Only)

Trunk Ports

Layer 2 to Layer 3 Port Conversion

Port-VLAN Association Changes

PACL and VACL Interactions

PACL Interaction with VACLs and Cisco IOS ACLs

Bridged Packets

Routed Packets

Multicast Packets

Configuring PACLs

PACL Configuration Guidelines

Configuring IP and MAC ACLs on a Layer 2 Interface

Configuring Access-group Mode on Layer 2 Interface

Applying ACLs to a Layer 2 Interface

Applying ACLs to a Port Channel

Displaying an ACL Configuration on a Layer 2 Interface

Configuring VACLs

VACL Configuration Overview

Defining a VLAN Access Map

Configuring a Match Clause in a VLAN Access Map Sequence

Configuring an Action Clause in a VLAN Access Map Sequence

Applying a VLAN Access Map

Verifying VLAN Access Map Configuration

VLAN Access Map Configuration and Verification Examples

Configuring a Capture Port

Configuring VACL Logging

Configuring Port ACLs and VLAN ACLs

This chapter describes how to configure port ACLs (PACLs) and VLAN ACLs (VACLs) in CiscoIOSSoftware Release12.2SX.

Note•For complete syntax and usage information for the commands used in this chapter, see the Cisco IOS Software Releases 12.2SX Command References at thisURL:

http://www.cisco.com/en/US/docs/ios/mcl/122sx_mcl.html

•OAL and VACL capture are incompatible. Do not configure both features on the switch. With OAL configured (see the "Optimized ACL Logging" section on page42-7), use SPAN to capture traffic.

•Port ACLs do not support the access-list keywords log or reflexive. These keywords in the access list are ignored. Optimized ACL logging (OAL) does not support PACLs.

•PACLs are not supported on Private VLANs.

This chapter consists of these sections:

•Understanding ACLs

•Configuring PACLs

•Configuring VACLs

•Configuring VACL Logging

Understanding ACLs

The following sections describe ACLs in CiscoIOSSoftware Release12.2SX:

•Understanding ACLs

•Understanding VACLs

•Understanding Port ACLs

•PACL and VACL Interactions

Understanding ACLs

Access control lists (ACLs) provide the ability to filter ingress and egress traffic based on conditions specified in the ACL.

CiscoIOSSoftware Release12.2SX supports the following types of ACLs:

•Cisco IOS ACLs are applied to Layer 3 interfaces. They filter traffic routed between VLANs. For more information about Cisco IOS ACLs, see Chapter42, "Understanding Cisco IOS ACL Support."

•VACLs control access to the VLAN of all packets (bridged and routed). Packets can either enter the VLAN through a Layer2 port or through a Layer3 port after being routed. You can also use VACLs to filter traffic between devices in the same VLAN.

•Port ACLs perform access control on all traffic entering the specified Layer 2 port.

PACLs and VACLs can provide access control based on the Layer 3 addresses (for IP protocols) or Layer 2 MAC addresses (for non-IP protocols).

You can apply only one IP access list and one MAC access list to a Layer2 interface.

Understanding VACLs

VLAN ACLs (VACLs) can provide access control for all packets that are bridged within a VLAN or that are routed into or out of a VLAN or a WAN interface for VACL capture. Unlike Cisco IOS ACLs that are applied on routed packets only, VACLs apply to all packets and can be applied to any VLAN or WAN interface. VACLs are processed in the ACL TCAM hardware. VACLs use the same configuration commands as Cisco IOS ACLs. VACLs ignore any Cisco IOS ACL fields that are not supported in hardware.

You can configure VACLs for IP, IPX, and MAC-Layer traffic. VACLs applied to WAN interfaces support only IP traffic for VACL capture.

If a VACL is configured for a packet type, and a packet of that type does not match the VACL, the default action is to deny the packet.

Note•TCP Intercepts and Reflexive ACLs take precedence over a VACL action if these features are configured on the same interface as a VACL.

•VACLs and CBAC cannot be configured on the same interface.

•IGMP packets are not checked against VACLs.

Understanding Port ACLs

The port ACL (PACL) feature provides the ability to perform access control on specific Layer 2 ports. A Layer 2 port is a physical LAN or trunk port that belongs to a VLAN. Port ACLs are only applied on the ingress traffic. The port ACL feature is supported only in hardware (port ACLs are not applied to any packets routed in software).

When you create a port ACL, an entry is created in the ACL TCAM. You can use the show tcam counts command to see how much TCAM space is available.

The PACL feature does not affect Layer 2 control packets received on the port.

You can use the access-group mode command to change the way that PACLs interact with other ACLs.

PACLs use the following modes:

•Prefer port mode—If a PACL is configured on a Layer 2 interface, the PACL takes effect and overwrites the effect of other ACLs (Cisco IOS ACL and VACL). If no PACL feature is configured on the Layer 2 interface, other features applicable to the interface are merged and are applied on the interface.

•Merge mode—In this mode, the PACL, VACL, and Cisco IOS ACLs are merged in the ingress direction following the logical serial model shown in Figure43-2. This is the default access group mode.

You configure the access-group mode command on each interface. The default is merge mode.

NoteA PACL can be configured on a trunk port. Trunk ports do not support merge mode.

To illustrate access group mode, assume a physical port belongs to VLAN100, and the following ACLs are configured:

•Cisco IOS ACL R1 is applied on routed interface VLAN100.

•VACL (VLAN filter) V1 is applied on VLAN100.

•PACL P1 is applied on the physical port.

In this situation, the following ACL interactions occur:

•In prefer port mode, Cisco IOS ACL R1 and VACL V1 are ignored.

•In merge mode, Cisco IOS ACL R1, VACL V1 and PACL P1 are merged and applied on the port.

NoteThe CLI syntax for creating a PACL is identical to the syntax for creating a Cisco IOS ACL. An instance of an ACL that is mapped to a Layer 2 port is called a PACL. An instance of an ACL that is mapped to a Layer 3 interface is called a Cisco IOS ACL. The same ACL can be mapped to both a Layer2 port and a Layer 3 interface.

The PACL feature supports MAC ACLs and IPv4 ACLs. The PACL feature does not support ACLs for IPV6, ARP, or MPLS traffic.

PACLs are explained in more detail in the following sections:

•EtherChannel and PACL Interactions

•Dynamic ACLs (Applies to Merge Mode Only)

•Trunk Ports

•Port-VLAN Association Changes

EtherChannel and PACL Interactions

This section describes the guidelines for the EtherChannel and PACL interactions:

•PACLs are supported on the main Layer 2 channel interface, but not on the port members. When a port is added to the EtherChannel, any PACL present on the port becomes inactive (but kept in the configuration). If the port is removed from the EtherChannel, any PACL configured on the port becomes active again.

•Changing the configuration on the logical port affects all the ports in the channel. When an ACL is mapped to the logical port belonging to a channel, it is mapped to all ports in the channel.

Dynamic ACLs (Applies to Merge Mode Only)

Dynamic ACLs are VLAN-based and are used by two features: CBAC and GWIP. The merge mode does not support the merging of the dynamic ACLs with the PACLs. In merge mode, the following configurations are not allowed:

•Attempting to apply a PACL on a port where its corresponding VLAN has a dynamic ACL mapped. In this case, the PACL is not applied to traffic on the port.

•Configuring a dynamic ACL on a VLAN where one of its constituent ports has a PACL installed. In this case, the dynamic ACL is not applied.

Trunk Ports

A PACL can be configured on a trunk port in merge mode only.

Layer 2 to Layer 3 Port Conversion

If you reconfigure a port from Layer2 to Layer3, any PACL configured on the port becomes inactive but remains in the configuration. If you subsequently configure the port as Layer 2, any PACL configured on the port becomes active again.

Port-VLAN Association Changes

You can enter port configuration commands that alter the port-VLAN association, which triggers an ACL remerge.

Unmapping and then mapping a PACL, VACL, or Cisco IOS ACL automatically triggers a remerge.

In merge mode, online insertion or removal of a switching module also triggers a remerge, if ports on the module have PACLs configured.

PACL and VACL Interactions

The following sections describe interactions between the different types of ACL:

•PACL Interaction with VACLs and Cisco IOS ACLs

•Bridged Packets

•Routed Packets

•Multicast Packets

PACL Interaction with VACLs and Cisco IOS ACLs

This section describes the guidelines for the PACL interaction with the VACLs and Cisco IOS ACLs.

For an incoming packet on a physical port, the PACL is applied first. If the packet is permitted by the PACL, the VACL on the ingress VLAN is applied next. If the packet is Layer 3 forwarded and is permitted by the VACL, it is filtered by the Cisco IOS ACL on the same VLAN. The same process happens in reverse in the egress direction. However, there is currently no hardware support for output PACLs.

The PACLs override both the VACLs and Cisco IOS ACLs when the port is configured in prefer port mode. The one exception to this rule is when the packets are forwarded in the software by the route processor (RP). The RP applies the ingress Cisco IOS ACL regardless of the PACL mode. Two examples where the packets are forwarded in the software are as follows:

•Packets that are egress bridged (due to logging or features such as NAT)

•Packets with IP options

Bridged Packets

Figure43-1 shows a PACL and a VACL applied to bridged packets. In merge mode, the ACLs are applied in the following order:

1.PACL for the ingress port

2.VACL for the ingress VLAN

3.VACL for the egress VLAN

Figure43-1Applying ACLs on Bridged Packets

In prefer port mode, only the PACL is applied to the ingress packets (the input VACL is not applied).

Routed Packets

Figure43-2 shows how ACLs are applied on routed and Layer 3-switched packets. In merge mode, the ACLs are applied in the following order:

1.PACL for the ingress port

2.VACL for the ingress VLAN

3.Input Cisco IOS ACL

4.Output Cisco IOS ACL

5.VACL for the egress VLAN

In prefer port mode, only the PACL is applied to the ingress packets (the input VACL and Cisco IOS ACL are not applied).

Figure43-2Applying ACLs on Routed Packets

Multicast Packets

Figure43-3 shows how ACLs are applied on packets that need multicast expansion. For packets that need multicast expansion, the ACLs are applied in the following order:

1.Packets that need multicast expansion:

a.PACL for the ingress port

b.VACL for the ingress VLAN

c.Input Cisco IOS ACL

2.Packets after multicast expansion:

a.Output Cisco IOS ACL

b.VACL for the egress VLAN

3.Packets originating from router:

a.Output Cisco IOS ACL

b.VACL for the egress VLAN

In prefer port mode, only the PACL is applied to the ingress packets (the input VACL and Cisco IOS ACL are not applied).

Figure43-3Applying ACLs on Multicast Packets

Configuring PACLs

Release12.2(33)SXH and later releases support PACLs. This section describes how to configure PACLs. PACLs filter incoming traffic on Layer 2 interfaces, using Layer 3 information, Layer 4 header information, or non-IP Layer 2 information.

The PACL feature uses existing Cisco IOS access-list commands to create the standard or extended IP ACLs or named MAC-extended ACLs that you want to apply to the port.

Use the ip access-group or mac access-group interface command to apply an IP ACL or MAC ACL to one or more Layer 2 interfaces.

This section contains the following topics:

•PACL Configuration Guidelines

•Configuring IP and MAC ACLs on a Layer 2 Interface

•Configuring Access-group Mode on Layer 2 Interface

•Applying ACLs to a Layer 2 Interface

•Applying ACLs to a Port Channel

•Displaying an ACL Configuration on a Layer 2 Interface

PACL Configuration Guidelines

Consider the following guidelines when configuring PACLs:

•There can be at most one IP access list and one MAC access list applied to the same Layer 2 interface per direction.

•An IP access list filters only IPv4 packets, For IP access lists, you can define a standard, extended or named access-list.

•A MAC access list filters all ingress packets based on Layer 2 information. You can define only named MAC access lists.

•The number of ACLs and ACEs that can be configured as part of a PACL are bounded by the hardware resources on the switch. Those hardware resources are shared by various ACL features (such as Cisco IOS ACL or VACL) that are configured on the system. If there are insufficient hardware resources to program a PACL in hardware, the PACL is not applied.

•PACL does not support the access-list log and reflect/evaluate keywords. These keywords are ignored if you add them to the access list for a PACL.

•Optimized ACL logging (OAL) does not support PACLs.

•PACLs are not applied to IPv6, MPLS, or ARP messages.

•The access group mode can change the way PACLs interact with other ACLs. To maintain consistent behavior across Cisco platforms, use the default access group mode (merge mode).

Configuring IP and MAC ACLs on a Layer 2 Interface

IP and MAC ACLs can be applied to Layer 2 physical interfaces. Standard (numbered, named) and Extended (numbered, named) IP ACLs, and Extended Named MAC ACLs are supported.

To apply IP or MAC ACLs on a Layer 2 interface, perform this task:

Switch# configure terminal 

Switch(config)# interface interface 

Switch(config-if)# {ip | mac } access-group {name| number | in | out}

Switch(config)# show running-config

The following example shows how to configure the Extended Named IP ACL simple-ip-acl to permit all TCP traffic and implicitly deny all other IP traffic:

Switch(config)# ip access-list extended simple-ip-acl 

Switch(config-ext-nacl)# permit tcp any any

Switch(config-ext-nacl)# end

The following example shows how to configure the Extended Named MAC ACL simple-mac-acl to permit source host 000.000.011 to any destination host:

Switch(config)# mac access-list extended simple-mac-acl

Switch(config-ext-macl)# permit host 000.000.011 any

Switch(config-ext-macl)# end

Configuring Access-group Mode on Layer 2 Interface

To configure the access mode on a Layer 2 interface, perform this task:

Switch# configure t

Switch(config)# interface interface

Switch(config-if)# [no] access-group mode {preferport | merge}

Switch(config)# show running-config

This example shows how to configure an interface to use prefer port mode:

Switch# configure terminal

Switch(config)# interface gigabitEthernet 6/1

Switch(config-if)# access-group mode prefer port

This example shows how to configure an interface to use merge mode:

Switch# configure terminal

Switch(config)# interface gigabitEthernet 6/1

Switch(config-if)# access-group mode merge

Applying ACLs to a Layer 2 Interface

To apply IP and MAC ACLs to a Layer 2 interface, perform one of these tasks:

Switch(config-if)# ip access-group ip-acl {in | out}

Switch(config-if)# mac access-group mac-acl {in | out}

This example applies the extended named IP ACL simple-ip-acl to interface GigabitEthernet 6/1 ingress traffic:

Switch# configure t

Switch(config)# interface gigabitEthernet 6/1

Switch(config-if)# ip access-group simple-ip-acl in

This example applies the extended named MAC ACL simple-mac-acl to interface GigabitEthernet 6/1 ingress traffic:

Switch# configure t

Switch(config)# interface gigabitEthernet 6/1

Switch(config-if)# mac access-group simple-mac-acl in

Applying ACLs to a Port Channel

To apply IP and MAC ACLs to a port channel logical interface, perform this task:

Switch(config-if)# interface port-channel number

Switch(config-if)# ip access-group ip-acl {in | out}

Switch(config-if)# mac access-group mac-acl {in | out}

This example applies the extended named IP ACL simple-ip-acl to port channel 3 ingress traffic:

Switch# configure t

Switch(config)# interface port-channel 3

Switch(config-if)# ip access-group simple-ip-acl in

Displaying an ACL Configuration on a Layer 2 Interface

To display information about an ACL configuration on Layer 2 interfaces, perform one of these tasks:

Switch# show ip access-lists [interface interface-name]

Switch# show mac access-group [interface interface-name]

Switch# show access-group mode [interface interface-name]

This example shows that the IP access group simple-ip-acl is configured on the inbound direction of interface fa6/1:

Switch# show ip interface fast 6/1

FastEthernet6/1 is up, line protocol is up

 Inbound access list is simple-ip-acl

 Outgoing access list is not set

This example shows that MAC access group simple-mac-acl is configured on the inbound direction of interface fa6/1:

Switch# show mac access-group interface fast 6/1

Interface FastEthernet6/1:

 Inbound access-list is simple-mac-acl 

 Outbound access-list is not set

This example shows that access group merge is configured on interface fa6/1:

Switch# show access-group mode interface fast 6/1

Interface FastEthernet6/1:

 Access group mode is: merge

Configuring VACLs

These sections describe how to configure VACLs:

•VACL Configuration Overview

•Defining a VLAN Access Map

•Configuring a Match Clause in a VLAN Access Map Sequence

•Configuring an Action Clause in a VLAN Access Map Sequence

•Applying a VLAN Access Map

•Verifying VLAN Access Map Configuration

•VLAN Access Map Configuration and Verification Examples

•Configuring a Capture Port

VACL Configuration Overview

VACLs use standard and extended Cisco IOS IP and IPX ACLs, and MAC Layer-named ACLs (see the "Configuring MAC ACLs" section on page36-63) and VLAN access maps.

VLAN access maps can be applied to VLANs or to WAN interfaces for VACL capture. VACLs attached to WAN interfaces support only standard and extended Cisco IOS IP ACLs.

Each VLAN access map can consist of one or more map sequences, each sequence with a match clause and an action clause. The match clause specifies IP, IPX, or MAC ACLs for traffic filtering and the action clause specifies the action to be taken when a match occurs. When a flow matches a permit ACL entry, the associated action is taken and the flow is not checked against the remaining sequences. When a flow matches a deny ACL entry, it will be checked against the next ACL in the same sequence or the next sequence. If a flow does not match any ACL entry and at least one ACL is configured for that packet type, the packet is denied.

To apply access control to both bridged and routed traffic, you can use VACLs alone or a combination of VACLs and ACLs. You can define ACLs on the VLAN interfaces to apply access control to both the ingress and egress routed traffic. You can define a VACL to apply access control to the bridged traffic.

The following caveats apply to ACLs when used with VACLs:

•Packets that require logging on the outbound ACLs are not logged if they are denied by a VACL.

•VACLs are applied on packets before NAT translation. If the translated flow is not subject to access control, the flow might be subject to access control after the translation because of the VACL configuration.

The action clause in a VACL can be forward, drop, capture, or redirect. Traffic can also be logged. VACLs applied to WAN interfaces do not support the redirect or log actions.

Note•VACLs have an implicit deny at the end of the map; a packet is denied if it does not match any ACL entry, and at least one ACL is configured for the packet type.

•If an empty or undefined ACL is specified in a VACL, any packets will match the ACL and the associated action is taken.

Defining a VLAN Access Map

To define a VLAN access map, perform this task:

When defining a VLAN access map, note the following information:

•To insert or modify an entry, specify the map sequence number.

•If you do not specify the map sequence number, a number is automatically assigned.

•You can specify only one match clause and one action clause per map sequence.

•Use the no keyword with a sequence number to remove a map sequence.

•Use the no keyword without a sequence number to remove the map.

See the "VLAN Access Map Configuration and Verification Examples" section.

Configuring a Match Clause in a VLAN Access Map Sequence

To configure a match clause in a VLAN access map sequence, perform this task:

When configuring a match clause in a VLAN access map sequence, note the following information:

•You can select one or more ACLs.

•VACLs attached to WAN interfaces support only standard and extended Cisco IOS IP ACLs.

•Use the no keyword to remove a match clause or specified ACLs in the clause.

•For information about named MAC-Layer ACLs, see the "Configuring MAC ACLs" section on page36-63.

•For information about Cisco IOS ACLs, see the Cisco IOSSecurity Configuration Guide, Release 12.2, "Traffic Filtering and Firewalls," at thisURL:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fsecur_c/ftrafwl/index.htm

See the "VLAN Access Map Configuration and Verification Examples" section.

Configuring an Action Clause in a VLAN Access Map Sequence

To configure an action clause in a VLAN access map sequence, perform this task:

When configuring an action clause in a VLAN access map sequence, note the following information:

•You can set the action to drop, forward, forward capture, or redirect packets.

•VACLs applied to WAN interfaces support only the forward capture action. VACLs applied to WAN interfaces do not support the drop, forward, or redirect actions.

•Forwarded packets are still subject to any configured Cisco IOS security ACLs.

•The capture action sets the capture bit for the forwarded packets so that ports with the capture function enabled can receive the packets. Only forwarded packets can be captured. For more information about the capture action, see the "Configuring a Capture Port" section.

•VACLs applied to WAN interfaces do not support the log action.

•When the log action is specified, dropped packets are logged in software. Only dropped IP packets can be logged.

•The redirect action allows you to specify up to five interfaces, which can be physical interfaces or EtherChannels. You cannot specify packets to be redirected to an EtherChannel member or a VLAN interface.

•The redirect interface must be in the VLAN for which the VACL access map is configured.

•If a VACL is redirecting traffic to an egress SPAN source port, SPAN does not copy the VACL-redirected traffic.

•SPAN and RSPAN destination ports transmit VACL-redirected traffic.

•Use the no keyword to remove an action clause or specified redirect interfaces.

See the "VLAN Access Map Configuration and Verification Examples" section.

Applying a VLAN Access Map

To apply a VLAN access map, perform this task:

When applying a VLAN access map, note the following information:

•You can apply the VLAN access map to one or more VLANs or WAN interfaces.

•The vlan_list parameter can be a single VLAN ID or a comma-separated list of VLAN IDs or VLAN ID ranges (vlan_ID-vlan_ID).

•If you delete a WAN interface that has a VACL applied, the VACL configuration on the interface is also removed.

•You can apply only one VLAN access map to each VLAN or WAN interface.

•VACLs applied to VLANs are active only for VLANs with a Layer 3 VLAN interface configured. Applying a VLAN access map to a VLAN without a Layer 3 VLAN interface creates an administratively down Layer 3 VLAN interface to support the VLAN access map.

•VACLs applied to VLANs are inactive if the Layer 2 VLAN does not exist or is not operational.

•You cannot apply a VACL to a secondary private VLAN. VACLs applied to primary private VLANs also apply to secondary private VLANs.

•Use the no keyword to clear VLAN access maps from VLANs or WAN interfaces.

See the "VLAN Access Map Configuration and Verification Examples" section.

Verifying VLAN Access Map Configuration

To verify VLAN access map configuration, perform this task:

VLAN Access Map Configuration and Verification Examples

Assume IP-named ACL net_10 and any_host are defined as follows:

Router# show ip access-lists net_10

Extended IP access list net_10

 permit ip 10.0.0.0 0.255.255.255 any

Router# show ip access-lists any_host

Standard IP access list any_host

 permit any

This example shows how to define and apply a VLAN access map to forward IP packets. In this example, IP traffic matching net_10 is forwarded and all other IP packets are dropped due to the default drop action. The map is applied to VLAN 12 to 16.

Router(config)# vlan access-map thor 10

Router(config-access-map)# match ip address net_10

Router(config-access-map)# action forward 

Router(config-access-map)# exit 

Router(config)# vlan filter thor vlan-list 12-16 

This example shows how to define and apply a VLAN access map to drop and log IP packets. In this example, IP traffic matching net_10 is dropped and logged and all other IP packets are forwarded:

Router(config)# vlan access-map ganymede 10

Router(config-access-map)# match ip address net_10

Router(config-access-map)# action drop log

Router(config-access-map)# exit

Router(config)# vlan access-map ganymede 20

Router(config-access-map)# match ip address any_host

Router(config-access-map)# action forward

Router(config-access-map)# exit

Router(config)# vlan filter ganymede vlan-list 7-9 

This example shows how to define and apply a VLAN access map to forward and capture IP packets. In this example, IP traffic matching net_10 is forwarded and captured and all other IP packets are dropped:

Router(config)# vlan access-map mordred 10 

Router(config-access-map)# match ip address net_10

Router(config-access-map)# action forward capture

Router(config-access-map)# exit

Router(config)# vlan filter mordred vlan-list 2, 4-6 

Configuring a Capture Port

A port configured to capture VACL-filtered traffic is called a capture port.

NoteTo apply IEEE 802.1Q or ISL tags to the captured traffic, configure the capture port to trunk unconditionally (see the "Configuring the Layer 2 Switching Port as an ISL or 802.1Q Trunk" section on page13-9 and the "Configuring the Layer 2 Trunk Not to Use DTP" section on page13-10).

To configure a capture port, perform this task:

When configuring a capture port, note the following information:

•You can configure any port as a capture port.

•The vlan_list parameter can be a single VLAN ID or a comma-separated list of VLAN IDs or VLAN ID ranges (vlan_ID-vlan_ID).

•To encapsulate captured traffic, configure the capture port with the switchport trunk encapsulation command (see the "Configuring a Layer 2 Switching Port as a Trunk" section on page13-9) before you enter the switchport capture command.

•For unencapsulated captured traffic, configure the capture port with the switchport mode access command (see the "Configuring a LAN Interface as a Layer 2 Access Port" section on page13-15) before you enter the switchport capture command.

•The capture port supports only egress traffic. No traffic can enter the switch through a captureport.

This example shows how to configure a Fast Ethernet interface 5/1 as a capture port:

Router(config)# interface gigabitEthernet 5/1 

Router(config-if)# switchport capture 

Router(config-if)# end

This example shows how to display VLAN access map information:

Router# show vlan access-map mordred 

Vlan access-map "mordred" 10

 match: ip address net_10

 action: forward capture

Router# 

This example shows how to display mappings between VACLs and VLANs. For each VACL map, there is information about the VLANs that the map is configured on and the VLANs that the map is active on. A VACL is not active if the VLAN does not have an interface.

Router# show vlan filter 

VLAN Map mordred:

 Configured on VLANs: 2,4-6

 Active on VLANs: 2,4-6

Router# 

Configuring VACL Logging

When you configure VACL logging, IP packets that are denied generate log messages in these situations:

•When the first matching packet is received

•For any matching packets received during the last 5-minute interval

•If the threshold is reached before the 5-minute interval

Log messages are generated on a per-flow basis. A flow is defined as packets with the same IP addresses and Layer4 (UDP or TCP) port numbers. When a log message is generated, the timer and packet count is reset.

These restrictions apply to VACL logging:

•Because of the rate-limiting function for redirected packets, VACL logging counters may not be accurate.

•Only denied IP packets are logged.

To configure VACL logging, use the action drop log command action in VLAN access map submode (see the "Configuring PACLs" section for configuration information) and perform this task in global configuration mode to specify the global VACL logging parameters:

This example shows how to configure global VACL logging in hardware:

Router(config)# vlan access-log maxflow 800 

Router(config)# vlan access-log ratelimit 2200 

Router(config)# vlan access-log threshold 4000