Short introduction about private VLAN and the platforms that support it.

Private VLAN, also known as port isolation, is a technique in computer networking where a VLAN contains switch ports that are restricted such that they can only communicate with a given "uplink". The restricted ports are called "private ports". Each private VLAN typically contains many private ports, and a single uplink. The uplink will typically be a port (or link aggregation group) connected to a router, firewall, server, provider network, or similar central resource.

VLANs limit broadcasts to specified users. Private VLANs (PVLANs) take this concept a step further by limiting communication within a VLAN. PVLANs accomplish this by restricting traffic flows through their member switch ports (which are called private ports) so that these ports communicate only with a specified uplink trunk port or with specified ports within the same VLAN. The uplink trunk port or link aggregation group (LAG) is usually connected to a router, firewall, server, or provider network. Each PVLAN typically contains many private ports that communicate only with a single uplink port, thereby preventing the ports from communicating with each other.

PVLANs provide Layer 2 isolation between ports within a VLAN, splitting a broadcast domain into multiple discrete broadcast subdomains by creating secondary VLANs (community VLANs and an isolated VLAN) inside a primary VLAN. Ports within the same community VLAN can communicate with each other. Ports within an isolated VLAN can communicate only with a single uplink port.

Just like regular VLANs, PVLANs are isolated on Layer 2 and require one of the following options to route Layer 3 traffic among the secondary VLANs:

• A promiscuous port connection with a router
• A routed VLAN interface (RVI)

PVLANs are useful for restricting the flow of broadcast and unknown unicast traffic and for limiting the communication between known hosts. Service providers use PVLANs to keep their customers isolated from each other. Another typical use for a PVLAN is to provide per-room Internet access in a hotel.

Private VLAN are supported on the following platforms:

EX2300
EX2300-C
EX2300 Multigigabit
EX3400
EX3400-VC
EX4000-12MP
EX4000-24MP
EX4000-48MP
EX4100
EX4100-F
EX4100 Multigigabit
EX4300
EX4300-VC
EX4300 Multigigabit
EX4400
EX4400 Multigigabit
EX4400-24X
EX4600
EX4600-VC
EX4650-48Y
EX9200
EX9251
EX9253
MX204
MX240
MX304
MX480
MX960
MX10003
MX10004
MX10008
MX10016
QFX5100
QFX5100-VC
QFX5110
QFX5120-48Y
QFX5120-32C
QFX5120-48T
QFX5120-48YM
QFX5200
QFX5210-64C