Layer 2 Switching Configuration Guide, Cisco DCNM for LAN, Release 5.x
Configuring Private VLANs
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Configuring Private VLANs

Contents

Configuring Private VLANs

This chapter describes how to configure private VLANs on Cisco NX-OS devices using Cisco Data Center Network Manager (DCNM) for LAN. For more information about the Cisco DCNM feature, see the .

This chapter includes the following sections:


Note


See the Interfaces Configuration Guide, Cisco DCNM for LAN, Release 5.x, for information on IP addressing for VLAN network interfaces.


Information About Private VLANs


Note


A Layer 2 port can function as either a trunk port, an access port, or a private VLAN port.



Note


Beginning with Cisco DCNM 5.1(1), the system supports private VLAN promiscuous turnk ports and isolated trunk ports. Private VLAN community ports cannot be trunk ports.

Note


You must enable the private VLAN feature before you can configure this feature.


In certain instances where similar systems do not need to interact directly, private VLANs provide additional protection at the Layer 2 level. Private VLANs are an association of primary and secondary VLANs.

A primary VLAN defines the broadcast domain with which the secondary VLANs are associated. The secondary VLANs may either be isolated VLANs or community VLANs. Hosts on isolated VLANs communicate only with associated promiscuous ports in primary VLANs, and hosts on community VLANs communicate only among themselves and with associated promiscuous ports but not with isolated ports or ports in other community VLANs.

In configurations that use integrated switching and routing functions, you can assign a single Layer 3 VLAN network interface to each private VLAN to provide routing. The VLAN network interface is created for the primary VLAN. In such configurations, all secondary VLANs communicate at Layer 3 only through a mapping with the VLAN network interface on the primary VLAN. Any VLAN network interfaces previously created on the secondary VLANs are put out-of-service.

The Cisco NX-OS release that is running on a managed device may not support all the features or settings described in this chapter. For the latest feature information and caveats, see the documentation and release notes for your platform and software release.

Primary and Secondary VLANs in Private VLANs

The private VLAN feature addresses two problems that users encounter when using VLANs:


  • Each VDC supports up to 4096 VLANs. If a user assigns one VLAN per customer, the number of customers that the service provider can support is limited.

  • To enable IP routing, each VLAN is assigned with a subnet address space or a block of addresses, which can result in wasting the unused IP addresses and creating IP address management problems.

Using private VLANs solves the scalability problem and provides IP address management benefits and Layer 2 security for customers.

The private VLAN feature allows you to partition the Layer 2 broadcast domain of a VLAN into subdomains. A subdomain is represented by a pair of private VLANs: a primary VLAN and a secondary VLAN. A private VLAN domain can have multiple private VLAN pairs, one pair for each subdomain. All VLAN pairs in a private VLAN domain share the same primary VLAN. The secondary VLAN ID differentiates one subdomain from another.


Note


A private VLAN domain has only one primary VLAN.


Secondary VLANs provide Layer 2 isolation between ports within the same private VLAN. The following two types are secondary VLANs within a primary VLAN:


  • Isolated VLANs—Ports within an isolated VLAN cannot communicate with each other at the Layer 2 level.

  • Community VLANs—Ports within a community VLAN can communicate with each other but cannot communicate with ports in other community VLANs or in any isolated VLANs at the Layer 2 level.

Private VLAN Ports


Note


Both community and isolated private VLAN ports are labeled as PVLAN host ports. A PVLAN host port is either a community PVLAN port or an isolated PVLAN port depending on the type of secondary VLAN with which it is associated.


The types of private VLAN ports are as follows:


  • Promiscuous port—A promiscuous port belongs to the primary VLAN. The promiscuous port can communicate with all interfaces, including the community and isolated host ports, that belong to those secondary VLANs associated to the promiscuous port and associated with the primary VLAN. You can have several promiscuous ports in a primary VLAN. Each promiscuous port can have several secondary VLANs, or no secondary VLANs, associated to that port. You can associate a secondary VLAN to more than one promiscuous port, as long as the promiscuous port and secondary VLANs are within the same primary VLAN. You may want to do this association for load balancing or redundancy purposes. You can also have secondary VLANs that are not associated to any promiscuous port, but these secondary VLANs cannot communicate to the Layer 3 interface.

    Beginning with Cisco NX-OS Release 5.0(2), the primary VLAN becomes inactive after you remove all the mapped secondary VLANs to that primary VLAN.

  • Promiscuous trunk—Beginning with Cisco NX-OS Release 5.0(2) and Cisco DCNM Release 5.1(1), on the Cisco Nexus 7000 Series devices, you can configure a promiscuous trunk port to carry traffic for multiple primary VLANs. You map the private VLAN primary VLAN and either all or selected associated VLANs to the promiscuous trunk port. Each primary VLAN and one associated and secondary VLAN is a private VLAN pair, and you can configure a maximum of 16 private VLAN pairs on each promiscuous trunk port.


    Note


    Private VLAN promiscuous trunk ports carry traffic for normal VLANs as well as for primary private VLANs.


  • Isolated port—An isolated port is a host port that belongs to an isolated secondary VLAN. This port has complete Layer 2 isolation from other ports within the same private VLAN domain, except that it can communicate with associated promiscuous ports. Private VLANs block all traffic to isolated ports except traffic from promiscuous ports. Traffic received from an isolated port is forwarded only to promiscuous ports. You can have more than one isolated port in a specified isolated VLAN, and each port is completely isolated from all other ports in the isolated VLAN.

  • Isolated or secondary trunk—Beginning with Cisco NX-OS Release 5.0(2) and Cisco DCNM Release 5.1(1) on the Cisco Nexus 7000 Series devices, you can configure an isolated trunk port to carry traffic for multiple isolated VLANs. Each secondary VLAN on an isolated trunk port must be associated with a different primary VLAN. You cannot put two secondary VLANs that are associated with the same primary VLAN on an isolated trunk port. Each primary VLAN and one associated secondary VLAN is a private VLAN pair, and you can configure a maximum of 16 private VLAN pairs on each isolated trunk port.

  • Community port—A community port is a host port that belongs to a community secondary VLAN. Community ports communicate with other ports in the same community VLAN and with associated promiscuous ports. These interfaces are isolated at Layer 2 from all other interfaces in other communities and from all isolated ports within the private VLAN domain.


Note


Because trunks can support the VLANs that carry traffic between promiscuous, isolated, and community ports, the isolated and community port traffic might enter or leave the device through a trunk interface.


Primary, Isolated, and Community Private VLANs

Because the primary VLAN has the Layer 3 gateway, you associate secondary VLANs with the primary VLAN in order to communicate outside the private VLAN. Primary VLANs and the two types of secondary VLANs, isolated VLANs and community VLANs, have these characteristics:


  • Primary VLAN— The primary VLAN carries traffic from the promiscuous ports to the (isolated and community) host ports and to other promiscuous ports.

  • Isolated VLAN —An isolated VLAN is a secondary VLAN that carries unidirectional traffic upstream from the hosts toward the promiscuous ports and the Layer 3 gateway. You can configure multiple isolated VLANs in a private VLAN domain, and all the traffic remains isolated within each one. In addition, each isolated VLAN can have several isolated ports, and the traffic from each isolated port also remains completely separate.

  • Community VLAN—A community VLAN is a secondary VLAN that carries upstream traffic from the community ports to the promiscuous port gateways and to other host ports in the same community. You can configure multiple community VLANs in a private VLAN domain. The ports within one community can communicate, but these ports cannot communicate with ports in any other community or isolated VLAN in the private VLAN.

This figure shows the Layer 2 traffic flows within a primary, or private VLAN, along with the types of VLANs and types of ports.


Figure 1. Private VLAN Layer 2 Traffic Flows


Note


The private VLAN traffic flows are unidirectional from the host ports to the promiscuous ports. Traffic that egresses the promiscuous port acts like the traffic in a normal VLAN, and there is no traffic separation among the associated secondary VLAN.


A promiscuous port can serve only one primary VLAN, but it can serve multiple isolated VLANs and multiple community VLANs. (Layer 3 gateways are connected to the device through a promiscuous port.) With a promiscuous port, you can connect a wide range of devices as access points to a private VLAN. For example, you can use a promiscuous port to monitor or back up all the private VLAN servers from an administration workstation.


Note


Beginning with Cisco DCNM Release 5.1(1) for the Nexus 7000 Series devices, you can configure private VLAN promiscuous and isolated trunk ports. These promiscuous and isolated trunk ports carry traffic for multiple primary and secondary VLANs as well as normal VLAN.


Although you can have several promiscuous ports in a primary VLAN, you can have only one Layer 3 gateway per primary VLAN.

In a switched environment, you can assign an individual private VLAN and associated IP subnet to each individual or common group of end stations. The end stations need to communicate only with a default gateway to communicate outside the private VLAN.


Note


You must enable the VLAN network interface feature before you can configure the Layer 3 gateway. See the Interfaces Configuration Guide, Cisco DCNM for LAN, Release 5.x, for complete information on VLAN network interfaces and IP addressing.


Associating Primary and Secondary VLANs

To allow the host ports in secondary VLANs to communicate outside the private VLAN, you associate secondary VLANs to the primary VLAN. If the association is not operational, the host ports (isolated and community ports) in the secondary VLAN are brought down.


Note


You can associate a secondary VLAN with only one primary VLAN.


For an association to be operational, the following conditions must be met:


  • The primary VLAN must exist.

  • The secondary VLAN must exist.

  • The primary VLAN must be configured as a primary VLAN.

  • The secondary VLAN must be configured as either an isolated or community VLAN.

If the association is not operational on private VLAN trunk ports, only that VLAN goes down, not the entire port.


Note


This behavior is different from how Catalyst devices work.

In order to change the association between a secondary and primary VLAN, you must first remove the current association and then add the desired association.

Broadcast Traffic in Private VLANs

Broadcast traffic from ports in a private VLAN flows in the following ways:


  • The broadcast traffic flows from all promiscuous ports to all ports in the primary VLAN. This broadcast traffic is distributed to all ports within the primary VLAN, including those ports that are not configured with private VLAN parameters.

  • The broadcast traffic from all isolated ports is distributed only to those promiscuous ports in the primary VLAN that are associated to that isolated port.

  • The broadcast traffic from community ports is distributed to all ports within the port’s community and to all promiscuous ports that are associated to the community port. The broadcast packets are not distributed to any other communities within the primary VLAN or to any isolated ports.

Private VLAN Port Isolation

You can use private VLANs to control access to end stations as follows:


  • Configure selected interfaces connected to end stations as isolated ports to prevent any communication at Layer 2. For example, if the end stations are servers, this configuration prevents Layer 2 communication between the servers.

  • Configure interfaces connected to default gateways and selected end stations (for example, backup servers) as promiscuous ports to allow all end stations access to a default gateway.

Private VLANs and VLAN Interfaces

A VLAN interface to a Layer 2 VLAN is also called a switched virtual interface (SVI). Layer 3 devices communicate with a private VLAN only through the primary VLAN and not through secondary VLANs.

Configure VLAN network interfaces only for primary VLANs. Do not configure VLAN interfaces for secondary VLANs. VLAN network interfaces for secondary VLANs are inactive while the VLAN is configured as a secondary VLAN. You will see the following actions if you misconfigure the VLAN interfaces:


  • If you try to configure a VLAN with an active VLAN network interface as a secondary VLAN, the configuration is not allowed until you disable the VLAN interface.

  • If you try to create and enable a VLAN network interface on a VLAN that is configured as a secondary VLAN, that VLAN interface remains disabled and the system returns an error.

When the primary VLAN is associated with and mapped to the secondary VLAN, any configuration on the primary VLAN is propagated to the secondary VLANs. For example, if you assign an IP subnet to the VLAN network interface on the primary VLAN, this subnet is the IP subnet address of the entire private VLAN.


Note


You must enable the VLAN interface feature before you configure VLAN interfaces. See the Interfaces Configuration Guide, Cisco DCNM for LAN, Release 5.x , for information on VLAN interfaces and IP addressing.


Private VLANs Across Multiple Devices

You can extend private VLANs across multiple devices by trunking the primary, isolated, and community VLANs to other devices that support private VLANs. To maintain the security of your private VLAN configuration and to avoid other uses of the VLANs configured to be private VLANs, configure private VLANs on all intermediate devices, including devices that have no private VLAN ports.

High Availability for Private VLANs

The software supports high availability for both stateful and stateless restarts, as during a cold reboot, for private VLANs. For the stateful restarts, the software supports a maximum of three retries. If you try more than 3 times within 10 seconds of a restart, the software reloads the supervisor module.

You can upgrade or downgrade the software seamlessly, with respect to private VLANs.

Beginning with Cisco DCNM Release 5.1(1), if you configure private VLAN promiscuous or isolated trunk ports, you must unconfigure those ports in order to downgrade the software.

Virtualization Support for Private VLANs

The software supports virtual device contexts (VDCs).


Note


See the Virtual Device Context Configuration Guide, Cisco DCNM for LAN, Release 5.xVirtual Device Context Configuration Guide, Cisco DCNM for LAN, Release 5.x for complete information on VDCs and assigning resources.


Each VLAN must have all of its private VLAN ports for both the primary VLAN and all secondary VLANs in the same VDC. Private VLANs cannot cross VDCs.

Licensing Requirements for Private VLANs

The following table shows the licensing requirements for this feature:

Product

License Requirement

Cisco DCNM

Private VLANs require no license. Any feature not included in a license package is bundled with the Cisco DCNM and is provided at no charge to you.

Cisco NX-OS

Private VLANs require no license. Any feature not included in a license package is bundled with the Cisco NX-OS system images and is provided at no extra charge to you. For a complete explanation of the Cisco NX-OS licensing scheme, see the Cisco NX-OS Licensing Guide.

However, using VDCs requires an Advanced Services license.

Prerequisites for Private VLANs

Private VLANs have the following prerequisites:


  • You must be logged onto the device.

  • If necessary, install the Advanced Services license and enter the desired VDC.

  • You must enable the private VLAN feature.

Guidelines and Limitations for Configuring Private VLANs

Private VLANs have the following configuration guidelines and limitations:


  • You must enable private VLANs before the device can apply the private VLAN functionality.

  • You must enable the VLAN interface feature before the device can apply this functionality.

  • Shut down the VLAN network interface for all VLANs that you plan to configure as secondary VLANs before you configure these VLANs.

  • You cannot configure a shared interface to be part of a private VLAN. For more details, see the .

Secondary and Primary VLAN Configuration

Follow these guidelines when configuring secondary or primary VLANs in private VLANs:


  • You cannot configure the default VLAN (VLAN1) or any of the internally allocated VLANs as primary or secondary VLANs.

  • A primary VLAN can have multiple isolated and community VLANs associated with it. An isolated or community VLAN can be associated with only one primary VLAN.

  • Although private VLANs provide host isolation at Layer 2, hosts can communicate with each other at Layer 3.

  • When a secondary VLAN is associated with the primary VLAN, the STP parameters of the primary VLAN, such as bridge priorities, are propagated to the secondary VLAN. However, STP parameters do not necessarily propagate to other devices. You should manually check the STP configuration to ensure that the spanning tree topologies for the primary, isolated, and community VLANs match exactly so that the VLANs can properly share the same forwarding database.

  • For normal trunk ports, note the following:


    • There is a separate instance of STP for each VLAN in the private VLAN.

    • STP parameters for the primary and all secondary VLANs must match.

    • The primary and all associated secondary VLANs should be in the same MST instance.

  • For nontrunking ports, note the following:


    • STP is aware only of the primary VLAN for any private VLAN host port; STP does not run on secondary VLANs on a host port.


Note


We recommend that you enable BPDU Guard on all ports that you configure as a host port; do not enable this feature on promiscuous ports.



  • For private VLAN promiscuous trunk ports, note the following:
    • You can configure a maximum of 16 private VLAN primary and secondary VLAN pairs on each promiscuous trunk port.

    • The native VLAN must be either a normal VLAN or a private VLAN primary VLAN. You cannot configure a private VLAN secondary VLAN as the native VLAN for a private VLAN promiscuous trunk port.

    • To downgrade a system that has private VLAN promiscuous trunk ports configured, you must unconfigure these ports.

  • For private VLAN isolated trunk ports, note the following:


    • You can configure a maximum of 16 private VLAN primary and secondary VLAN pairs on each isolated trunk port.

    • The native VLAN must be either a normal VLAN or a private VLAN secondary VLAN. You cannot configure a private VLAN primary port as the native VLAN for a private VLAN isolated trunk port.

    • To downgrade a system that has private VLAN isolated trunk ports configured, you must unconfigure these ports.

  • You can apply different Quality of Service (QoS) configurations to primary, isolated, and community VLANs.

  • To apply a VACL to all private VLAN traffic, map the secondary VLANs on the VLAN network interface of the primary VLAN, and then configure the VACLs on the VLAN network interface of the primary VLAN.

  • The VACLs that you apply to the VLAN network interface of a primary VLAN automatically apply to the associated isolated and community VLANs only after you have configured the mapping.

  • If you do not map the secondary VLAN to the VLAN network interface of the primary VLAN, you can have different VACLs for primary and secondary VLANs, which can cause problems.

  • Because traffic in a private VLAN flows in different directions in different VLANs, you can have different VACLs for ingressing traffic and different VACLs for egressing traffic prior to configuring the mapping.


Note


You must keep the same VACLs for the primary VLAN and all secondary VLANs in the private VLAN.



  • You can enable DHCP snooping on private VLANs. When you enable DHCP snooping on the primary VLAN, the DHCP configuration is propagated to the secondary VLANs. If you configure DHCP on a secondary VLAN, the configuration does not take effect if the primary VLAN is already configured.

  • Before you configure a VLAN as a secondary VLAN, you must shut down the VLAN network interface for the secondary VLAN.

  • To prevent interhost communication in isolated private VLANs with a promiscuous port, configure a role-based ACL (RBACL) that disallows hosts in that subnet from communicating with each other.

Private VLAN Port Configuration

Follow these guidelines when configuring private VLAN ports:


  • The Layer 2 access ports that are assigned to the VLANs that you configure as primary, isolated, or community VLANs are inactive while the VLAN is part of the private VLAN configuration. Layer 2 trunk interfaces, which may carry private VLANs, are active and remain part of the STP database.

  • Do not configure ports that belong to a port-channel group as private VLAN ports. While a port is part of the private VLAN configuration, any port-channel configuration for it is inactive.

  • If you delete a VLAN used in the private VLAN configuration, the private VLAN ports that are associated with the VLAN become inactive.

Limitations with Other Features

Consider these configuration limitations with other features when configuring private VLANs:


Note


In some cases, the configuration is accepted with no error messages, but the commands have no effect.



  • IGMP runs only on the primary VLAN and uses the configuration of the primary VLAN for all secondary VLANs.

  • Any IGMP join request in the secondary VLAN is treated as if it is received in the primary VLAN.

  • Private VLANs support these Switched Port Analyzer (SPAN) features:


    • You can configure a private VLAN port as a SPAN source port.

    • You can use VLAN-based SPAN (VSPAN) on primary, isolated, and community VLANs or use SPAN on only one VLAN to separately monitor egress or ingress traffic.

  • Private VLAN host or promiscuous ports cannot be a SPAN destination port.

  • A destination SPAN port cannot be an isolated port. (However, a source SPAN port can be an isolated port.)

  • You can configure SPAN to span both primary and secondary VLANs or to span either one if the user is interested only in ingress or egress traffic.

  • After you configure the association between the primary and secondary VLANs, the dynamic MAC addresses that learned the secondary VLANs are flushed.

  • After you configure the association between the primary and secondary VLANs, all static MAC addresses that were created on the secondary VLANs are inserted into the primary VLAN. If you delete the association, the static MAC addresses revert to the secondary VLANs only.

  • After you configure the association between the primary and secondary VLANs, you cannot create static MAC addresses for the secondary VLANs.

  • After you configure the association between the primary and secondary VLANs, if you delete the association, all static MAC addresses that were created on the primary VLANs remain on the primary VLAN only.

  • Port security features are not supported with private VLANs.

  • In private VLANs, STP controls only the primary VLAN.


Note


See the Security Configuration Guide, Cisco DCNM for LAN, Release 5.x, for information on configuring static MAC addresses.


Platform Support for Private VLANs

The following platforms support this feature but may implement it differently. For platform-specific information, including guidelines and limitations, system defaults, and configuration limits, see the corresponding documentation

Platform

Documentation

Cisco Nexus 7000 Series Switches

Cisco Nexus 7000 Series Switch Documentation

Cisco Catalyst 6500 Series Switches

Cisco Catalyst 6500 Series Switch Documentation

Cisco Nexys 3000 Series Switches

Cisco Nexus 3000 Series Switch Documentation

Configuring a Private VLAN

You must have already created the VLAN before you can assign the specified VLAN as a private VLAN.

See the Interfaces Configuration Guide, Cisco DCNM for LAN, Release 5.x, for information on assigning IP addresses to VLAN network interfaces.

Enabling Private VLANs

You must enable private VLANs on the device to have the private VLAN functionality.

You enable private VLANs on the device using the VLAN pane as shown in this figure.
Figure 2. Configuring Private VLANs

Procedure
Step 1   From the Feature Selector pane, choose Switching > VLAN to open the VLAN pane.
Step 2   In the Summary pane, click the Device View tab.
Step 3   In the Summary pane, click the device in which you want to create a VLAN.
Step 4   On the device, right-click and choose Enable Private VLAN Conditional Services from the drop-down list.
Step 5   (Optional) From the menu bar, choose File > Deploy to apply your changes to the device.

Configuring a VLAN as a Private VLAN


Note


Before you configure a VLAN as a secondary VLAN—that is, either a community or isolated VLAN—you must first shut down the VLAN network interface.

You can configure a VLAN as a private VLAN.

You create all VLANs that you want to use in the private VLAN as a primary VLAN, a community VLAN, or an isolated VLAN. You will later associate multiple isolated and multiple community VLANs to one primary VLAN. You can have many primary VLANs and associations, which means that you could have many private VLANs.

If you delete either the primary or secondary VLAN, the ports that are associated with the VLAN become inactive.

Before You Begin

Ensure that private VLANs are enabled.


Procedure
Step 1   From the Feature Selector pane, choose Switching > VLAN to open the VLAN pane.
Step 2   In the Summary pane, click the Device View tab.
Step 3   In the Summary pane, click the device in which you want to create a VLAN.
Step 4   On the menu, click New.
Step 5   From the drop-down list, choose Primary VLAN, Community VLAN, or Isolated VLAN.
Step 6   (Optional) In the VLAN ID column, enter the ID for the new VLAN. The VLAN is immediately created on the device with default settings.
Step 7   (Optional)To change the name of the VLAN, click in the Name column and enter the name that you want.
Step 8   (Optional) From the menu bar, choose VLAN > Delete to delete the specified VLAN. The system displays a message asking if you want to delete these VLANs. When you click Yes, those VLANs are immediately removed from the device.
Step 9   (Optional) From the menu bar, choose File > Deploy to apply your changes to the device.

Associating Secondary VLANs with a Primary Private VLAN

If you delete either the primary or secondary VLAN, the ports that are associated with the VLAN become inactive.

When you reconvert the specified VLAN to private VLAN mode, the original associations are reinstated.

If you delete either the primary or secondary VLAN, the ports that are associated with the VLAN become inactive. To change the existing association, you first remove the present association and then configure the new association.

You associate private VLANs using the VLAN pane shown in this figure.
Figure 3. Mapping Secondary VLANs to the VLAN Interface of a Primary VLAN

Procedure
Step 1   From the Feature Selector pane, choose Switching > VLAN to open the VLAN pane.
Step 2   In the Summary pane, click the Device View tab.
Step 3   In the Summary pane, click the device in which you want to associate a VLAN.
Step 4   In the Summary pane, click the primary VLAN. Tabs appear in the Details pane.
Step 5   Click the VLAN Details tab,
Step 6   Click the VLAN Settings section.
Step 7   (Optional) Right-click the Secondary VLANs area and enter the secondary VLAN that you want associated with this primary VLAN. The Secondary VLANs area displays the VLAN ID and the VLAN type of each associated secondary VLAN.
Step 8   (Optional)To add additional secondary VLANs to the primary VLAN, repeat Steps 4 through 7.
Step 9   (Optional) To delete secondary VLANs from the primary VLAN, click the Secondary VLANs area and select the VLAN that you want to remove from associating with the primary VLAN. Right-click and click Delete Secondary VLAN.
Step 10   (Optional) From the menu bar, choose File > Deploy  to apply your changes to the device.

Mapping Secondary VLANs to the VLAN Interface of a Primary VLAN

You map secondary VLANs to the VLAN interface of a primary VLAN. Isolated and community VLANs are both called secondary VLANs. To allow Layer 3 processing of private VLAN ingress traffic, you map secondary VLANs to the VLAN network interface of a primary VLAN.

Before You Begin

You must enable VLAN network interfaces before you configure the VLAN network interface. VLAN network interfaces on community or isolated VLANs that are associated with a primary VLAN will be out of service. Only the VLAN network interface on the primary VLAN is in service.

Before you configure a VLAN as a secondary VLAN—that is, either a community or isolated VLAN—you must first shut down the VLAN network interface for that VLAN.


Procedure
Step 1   From the Feature Selector pane, choose Switching > VLAN to open the VLAN pane.
Step 2   In the Summary pane, click the Device View tab.
Step 3   In the Summary pane, click the primary VLAN.
Step 4   From the menu bar, choose Actions > Add VLAN Network Interface. A window appears in the VLAN Settings section of the VLAN Details tab that allows you to configure the VLAN network interface.
Step 5   In the Description field, enter a description for the VLAN network interface.
Step 6   In the IP Address field, enter an IP address for the VLAN network interface.
Step 7   In the Netmask field, enter the netmask for the VLAN network interface.
Step 8   In the Admin State field, choose Up or Down from the drop-down list.
Step 9   (Optional)In the VLAN Network Interface area, click the drop-down list in the Secondary VLANs field and choose the associated secondary VLANs to add to the VLAN network interface of the primary VLAN.
Step 10   (Optional) From the menu bar, choose File > Deploy  to apply your changes to the device.

Configuring Private VLAN Host and Promiscuous Ports

You can configure private VLAN host ports and private VLAN promiscuous ports. In private VLANs, host ports are part of the secondary VLANs, which are either community VLANs or isolated VLANs. You can configure a Layer 2 interface as a private VLAN promiscuous port, and then you can associate that promiscuous port with the primary and secondary VLANs.


Note


We recommend that you enable BPDU Guard on all interfaces configured as a host port.


Procedure
Step 1   From the Feature Selector pane, choose Interfaces > Physical > Ethernet to open the Ethernet pane or choose Interfaces > Logical > Virtual Ethernet to open the Virtual Ethernet pane.
Step 2   From the Contents pane, in the Summary pane, double-click the device to display the interfaces.
Step 3   Double-click the slot to display the list of interfaces.
Step 4   Click the interface. The system highlights the interface in the Summary pane, and tabs appear in the Details pane.
Step 5   In the Details pane, click the Port Details tab.
Step 6   Click the Port Mode Settings section.
Step 7   From the Mode drop-down list, choose PVLAN Host or PVLAN Promiscuous to configure the port as an access port.
Step 8   Click the Secondary VLAN drop-down list, and choose the secondary VLANs that you want to configure for this interface. The Secondary VLAN window displays the configured secondary VLANs and primary VLAN with which each secondary VLAN is associated. When you choose the secondary VLAN, the system automatically populates the Primary VLAN field.
Step 9   (Optional) From the menu bar, choose File > Deploy to apply your changes to the device.

Copying a Private VLAN from One Device to Another

You can copy and paste the VLAN, along with its VLAN ID, name, type, admin stat, and admin status, from one device to another.

Procedure
Step 1   From the Feature Selector pane, choose Switching > VLAN to open the VLAN pane.
Step 2   In the Summary pane, click the Device View tab.
Step 3   Click the device from which you want to copy the private VLAN.
Step 4   Expand the view for the device.

The system lists the VLANs configured on that device.

Step 5   Highlight the private VLAN that you want to copy.
Step 6   From the menu bar, choose Actions > Copy.
Step 7   In the Summary pane, click the device to which you want to paste the private VLAN.
Step 8   From the menu bar, choose Actions > Paste.
Step 9   (Optional) From the menu bar, choose File > Deploy  to apply your changes to the device.

Configuring Private VLAN Promiscuous and Secondary Trunk Ports

You can configure private VLAN trunk ports in Cisco DCNM Ethernet Interface or VLAN screens.

Procedure
Step 1   From the Feature Selector pane, choose Interfaces > Physical > Ethernet.

The available devices appear in the Summary pane.

Step 2   From the Summary pane, double-click the device to display a list of slots.
Step 3   Double-click the slot to display a list of interfaces.
Step 4   Click the interface.

The system highlights the interface in the Summary pane, and tabs appear in the Details pane.

Step 5   From the Details pane, click the Port Details tab.
Step 6   From the Port Details tab, expand the Port Mode Settings section.

The port mode information appears.

Step 7   From the Mode drop-down list, choose PVLAN Trunk Promiscuous or PVLAN Trunk Secondary to configure the port as a trunk port.
Step 8   In the Allowed VLANs field, enter a list of allowed VLANs.

The allowed range is from 1 to 3967 and 4048 to 4093. The default is none.

Step 9   From the Native VLAN drop-down list, choose a VLAN to which the untagged packets are assigned.

If there is no native VLAN entered, or if the native VLAN is a secondary VLAN and the port does not have the association for the secondary VLAN, the untagged packets are dropped. The allowed range is from 1 to 3967 and 4048 to 4093. The default is VLAN 1.

Step 10   In the Trunk Associations table, right click and choose Add Row > Promiscuous or Secondary.
  • Promiscuous—Enter or choose the primary VLAN and its associated secondary VLANs in the newly added row. Multiple trunk associations can be specified for a PVLAN trunk promiscuous port so that it can carry multiple primary VLANs. If there is no trunk association, any packet received on the primary VLANs is dropped.
  • Secondary—Enter or choose the primary VLAN and its associated secondary isolated VLAN in the newly added row. For the secondary trunk port, multiple secondary isolated VLANs cannot be associated to a single primary VLAN. Multiple trunk associations can be specified for a PVLAN trunk secondary port so that it can carry multiple secondary VLANs. If there is no trunk association, any packet received on the secondary VLANs is dropped.
Step 11   From the menu bar, choose File > Deploy to apply your changes to the device.

Adding Ethernet Interfaces to Private VLANs as Promiscuous Trunks

You can add Ethernet interfaces to PVLANs as promiscuous trunks.

Procedure
Step 1   From the Feature Selector pane, choose Switching > VLAN.

The available devices appear in the Summary pane.

Step 2   From the Summary pane, double-click the device to display a VLAN summary table.
Step 3   Choose any primary VLAN in the VLAN summary table.
Step 4   In the Association pane, click Interfaces, and choose Add Port to VLAN as > Trunk Promiscuous.
Step 5   In the Promiscuous Ports table under the Primary VLAN Ports tab, associate at least one secondary VLAN for the selected primary VLAN.

The changes are automatically deployed in the device.


Adding Ethernet Interfaces to Private VLANs as Secondary Trunks

You can add Ethernet interfaces to PVLANs as secondary trunks.

Procedure
Step 1   From the Feature Selector pane, choose Switching > VLAN.

The available devices appear in the Summary pane.

Step 2   From the Summary pane, double-click the device to display a VLAN summary table.
Step 3   Choose any secondary isolated VLAN in the VLAN summary table.
Note    The selected secondary VLAN should be associated to a primary VLAN.
Step 4   In the Association pane, click Interfaces, and choose Add Port to VLAN as > Trunk Secondary.

The changes are automatically deployed in the device.


Displaying Private VLAN Statistics


  • VLAN Traffic Statistics—Displays information on private VLAN traffic such as Layer 2 unicast, multicast, and broadcast traffic, Layer 3 unicast and multicast traffic, and so forth.

Field Descriptions for Configuring a Private VLAN

See the Interfaces Configuration Guide, Cisco DCNM for LAN, Release 5.x, for descriptions of the fields that you use to configure private VLAN ports.

Additional References for Private VLANs—DCNM Version

Table 1 Related Documents

Related Topic

Document Title

Static MAC addresses, security

Security Configuration Guide, Cisco DCNM for LAN, Release 5.x

Cisco DCNM fundamentals

VDCs

Virtual Device Context Quick Start, Cisco DCNM for LAN, Release 5.x

Release notes

Cisco DCNM Release Notes, Release 5.x

Standards

Standards

Title

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

MIBs

MIBs

MIBs Link


  • CISCO-PRIVATE-VLAN-MIB

To locate and download MIBs, go to the following URL:

http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml

Feature History for Configuring Private VLANs—DCNM

This table lists the release history for this feature.
Table 2 Feature History for Configuring STP Enhancements

Feature Name

Releases

Feature Information

No changes.

4.2(1)