Configuring Private VLANs

Private VLAN Configuration Tasks

Multicast traffic is routed or bridged across private VLAN boundaries and within a single community VLAN. Multicast traffic is not forwarded between ports in the same isolated VLAN or between ports in different secondary VLANs.

Private VLANs and SVIs

In a Layer 3 switch, a switch virtual interface (SVI) represents the Layer 3 interface of a VLAN. Layer 3 devices communicate with a private VLAN only through the primary VLAN and not through secondary VLANs. Configure Layer 3 VLAN interfaces (SVIs) only for primary VLANs. You cannot configure Layer 3 VLAN interfaces for secondary VLANs. SVIs for secondary VLANs are inactive while the VLAN is configured as a secondary VLAN.

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

•If you try to create an SVI on a VLAN that is configured as a secondary VLAN and the secondary VLAN is already mapped at Layer 3, the SVI is not created, and an error is returned. If the SVI is not mapped at Layer 3, the SVI is created, but it is automatically shut down.

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

Private VLANs and Switch Stacks

Private VLANs can operate within the switch stack, and private-VLAN ports can reside on different stack members. However, some changes to the switch stack can impact private-VLAN operation:

•If a stack contains only one private-VLAN promiscuous port and the stack member that contains that port is removed from the stack, host ports in that private VLAN lose connectivity outside the private VLAN.

•If a stack master stack that contains the only private-VLAN promiscuous port in the stack fails or leaves the stack and a new stack master is elected, host ports in a private VLAN that had its promiscuous port on the old stack master lose connectivity outside of the private VLAN.

•If two stacks merge, private VLANs on the winning stack are not affected, but private-VLAN configuration on the losing switch is lost when that switch reboots.

Private VLAN Configuration Tasks

To configure a private VLAN, perform these steps:

1Set VTP mode to transparent.

2Create the primary and secondary VLANs and associate them.

Note If the VLAN is not created already, the private VLAN configuration process creates it.

 

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Cisco Systems WSC2960XR48FPSI Private Vlan Configuration Tasks, Private VLANs and SVIs, Private VLANs and Switch Stacks
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WSC2960XR48FPSI specifications

The Cisco WSC2960XR48FPSI is an advanced, high-performance switch that plays a vital role in today's enterprise networking environments. Designed for reliability and efficiency, it serves as a foundational component for organizations concentrating on network agility and scalability.

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