Installing and Administering LAN/9000 Software

116 Chapter5

LAN Resources

VLAN or Virtual LAN

VLANs are literally virtual LANs. A LAN can be deﬁned as a network

connecting devices inside asingle building orinside the buildings close to

each other. Typically, LANs are used to isolate broadcast domains for

better performance and manageability. VLAN technology, on the other

hand, allows us to separate the logical connectivity from physical

connectivity. Users are still connected via the normal physical cable

connections, but the connectivity is viewed from the station or

application perspective, and no longer limited to the boundaries of the

physical network topology. A VLAN may also be thought of as a single

switched LAN infrastructure segmented into logical partitions based on

certain trafﬁc attributes such as IP subnet, MAC address, application,

protocol, etc.

HP -UX VLAN is, therefore, a virtual networking technology which is

based on the IEEE 802.1Q/p standards. It is a host-based software

solution applicable to end-stations as opposed to switch-based VLANs.

With HP-UX VLAN, the end stations determine the VLAN association of

each Ethernet frame, and convey it to a switch (or other link partners)

via the VLAN tag, thereby relieving switches of the burden of snooping

into each inbound frame in determining a VLAN association.

Features of VLAN:

• HP-UX VLANs are implemented with host-based IEEE 802.1Q/p

compliant tagging to allow conﬁguring multiple VLANs on a given

Ethernet LAN card, based on their IP-subnet, protocol, or LAN card

port.

• HP-UX VLANs are for use over Fast Ethernet or Gigabit Ethernet

LAN cards running HP-UX 11i PA-RISC-based servers and

workstations. Up to 1024 VLANs are supported per LAN card port.

• HP-UX VLANs do not require you to rewrite applications, install new

hardware, or re-cable. They are also compatible with HP

MC/ServiceGuard as well as HP’s Online Addition and Replacement

(OLAR) capabilities.

• Physically dispersed workgroups can be logically connected within

the same broadcast domain to appear as if they were on the same

physical LAN.