IEEE 802.10• IEEE 802.1Q• Inter−Switch Link (ISL)• LAN Emulation (LANE)•
IEEE 802.10
The IEEE 802.10 standard is used to send VLAN information over a Fiber Distributed Data Interface (FDDI)
physical link. In this situation, ISL is disabled and IEEE 802.10 is used to forward the VLAN frames. The
Clear Header on a FDDI frame contains a Security Association Identifier (SAID), a Link Service Access Point
(LSAP), and the Management Defined Field (MDF). The SAID field in the frame header is used to identify
the VLAN.
The 802.10 protocol is used primarily to transport VLAN information over FDDI, and you will only find it
used on this type of physical media, primarily in FDDI backbones to transport VLAN information and data.
Cisco Standards
A standard is a basis that participating vendors use to maintain functionality and compatibility between
different vendors’ products on a network. For example, when you get a 100BaseT NIC from one vendor and
you purchase a second card from another vendor, standards ensure that they will work with each other in your
network.
With so many ideas for the implementation of virtual LANs, Cisco found it essential to set certain standards.
Cisco chose to submit its standardization to the IEEE Internetworking Subcommittee.
Other standards have been created for VLANs by the Internet Engineering Task Force (IETF). Standards
related to the use of Asynchronous Transfer Mode (ATM) and LANE have been designated by the ATM
forum. This section will concentrate on the standards created by the IEEE, IETF, and ATM forum. The main
focus will be on those standards created and submitted for standardization by Cisco to enhance VLANs in
their route processors and other switching products.
Organizations install high−speed switched networks in order to create a network that can efficiently handle
the growing demands of software and hardware applications. These installations can cause some unexpected
problems in the network. Some of the standards discussed in this section relate to monitoring and managing
VLAN networks and resources. This management enables organizations to reduce problems in their networks
and to increase functionality and compatibility of different vendor products on the networks.
IEEE 802.1Q
IEEE 802.1Q is called the “Standard for Virtual Bridged Local Area Networks”; it was created by the IEEE as
a standard method of frame tagging. It actually inserts a field into the frame to identify the VLAN, and it
creates a method used for identifying VLANs over a trunk link. The IEEE 802.1Q standard calls for a frame
tag identifier to identify VLANs in the frame header. This protocol calls for no encapsulation of the data, and
is used in only Ethernet physical media.
As a frame enters the switch fabric, it is tagged with additional information regarding the VLAN properties.
Just as in ISL (discussed next), the tag remains in the frame while it is forwarded from switch to switch; the
tag is removed prior to exiting the access link to the destination interface. Unlike ISL, which uses an external
tagging process, 802.1Q uses an internal tagging process by modifying the existing Ethernet frame itself. To
both access links and trunk links, the frame looks like a standard Ethernet frame. This process remains
completely transparent to the source interface and the destination interface.
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