35Private VLANs (PVLAN)The private VLAN (PVLAN) feature is supported on the Z9000 platform.For syntax details about the commands described in this chapter, refer to the Private VLANs commandschapter in the Dell Networking OS Command Line Reference Guide.Private VLANs extend the Dell Networking OS security suite by providing Layer 2 isolation between portswithin the same virtual local area network (VLAN). A PVLAN partitions a traditional VLAN into subdomainsidentified by a primary and secondary VLAN pair. Private VLANs block all traffic to isolated ports excepttraffic from promiscuous ports. Traffic received from an isolated port is forwarded only to promiscuousports or trunk ports.Example uses of PVLANs:• A hotel can use an isolated VLAN in a PVLAN to provide Internet access for its guests, while stoppingdirect access between the guest ports.• A service provider can provide Layer 2 security for customers and use the IP addresses moreefficiently, by using a separate community VLAN per customer and at the same time using the same IPsubnet address space for all community and isolated VLANs mapped to the same primary VLAN.– In more detail, community VLANs are especially useful in the service provider environmentbecause multiple customers are likely to maintain servers that must be strictly separated incustomer-specific groups. A set of servers owned by a customer could comprise a communityVLAN, so that those servers could communicate with each other, and would be isolated fromother customers. Another customer might have another set of servers in another communityVLAN. Another customer might want an isolated VLAN, which has one or more ports that are alsoisolated from each other.Private VLAN ConceptsReview the following PVLAN concepts before you create PVLANs on your system.The VLAN types in a PVLAN include:• Community VLAN — a type of secondary VLAN in a primary VLAN:– Ports in a community VLAN can communicate with each other.– Ports in a community VLAN can communicate with all promiscuous ports in the primary VLAN.– A community VLAN can only contain ports configured as host.• Isolated VLAN — a type of secondary VLAN in a primary VLAN:– Ports in an isolated VLAN cannot talk directly to each other.– Ports in an isolated VLAN can only communicate with promiscuous ports in the primary VLAN.– An isolated VLAN can only contain ports configured as host.• Primary VLAN — the base VLAN of a PVLAN:– A switch can have one or more primary VLANs, and it can have none.Private VLANs (PVLAN) 625
