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CHAPTER
7-1
Cisco ONS 15310-CL and Cisco ONS 15310-MA Ethernet Card Software Feature and Configuration Guide R8.5
78-18133-01
7
Configuring VLANs on the ML-Series Card
This chapter describes VLAN configurations for the ML-Series card. It describes how to configure
IEEE 802.1Q VLAN encapsulation. For more information about the Cisco IOS commands used in this
chapter, refer to the Cisco IOS Command Reference publication.
This chapter contains the following major sections:
• Understanding VLANs, page 7-1
• Configuring IEEE 802.1Q VLAN Encapsulation, page 7-2
• IEEE 802.1Q VLAN Configuration, page 7-3
• Monitoring and Verifying VLAN Operation, page 7-5
Note Configuring VLANs is optional. Complete general interface configurations before proceeding with
configuring VLANs as an optional step.
Understanding VLANs
VLANs enable network managers to group users logically rather than by physical location. A VLAN is
an emulation of a standard LAN that allows secure intragroup data transfer and communication to occur
without the traditional restraints placed on the network. It can also be considered a broadcast domain
that is set up within a switch. With VLANs, switches can support more than one subnet (or VLAN) on
each switch and give routers and switches the opportunity to support multiple subnets on a single
physical link. A group of devices that belong to the same VLAN, but are part of different LAN segments,
are configured to communicate as if they were part of the same LAN segment.
VLANs enable efficient traffic separation and provide excellent bandwidth utilization. VLANs also
alleviate scaling issues by logically segmenting the physical LAN structure into different subnetworks
so that packets are switched only between ports within the same VLAN. This can be very useful for
security, broadcast containment, and accounting.
ML-Series software supports port-based VLANs and VLAN trunk ports, which are ports that carry the
traffic of multiple VLANs. Each frame transmitted on a trunk link is tagged as belonging to only one
VLAN.
ML-Series software supports VLAN frame encapsulation through the IEEE 802.1Q standard. The
Cisco Inter-Switch Link (ISL) VLAN frame encapsulation is not supported. ISL frames are broadcast at
Layer 2 or dropped at Layer 3.