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Ethernet Bridge and VLANs
4.1
VLAN Learning Constraints
Introduction
The supported self-learning VLAN bridge functionality operates according to IEEE 802.1Q. This learning
process creates the
The CLI commands explained in this section belong to the command group
Multiple filtering data bases
The Ethernet bridge supports multiple filtering data bases. Each filtering data base can be shared by multiple
VLANs.
VLAN learning constraints
The VLAN learning constraints used by the learning process determine which dynamic entries are created in
which filtering data bases.
Following VLAN learning constraints exist:
Shared VLAN Learning
that if an individual MAC address is learned in one VLAN, that learned information can be used in
forwarding decisions taken for that address by all other VLANs.
In this case, only one entry for a specific MAC address can exist. The same MAC address can not be
forwarded differently in different VLANs.
Independent VLAN Learning
by only one VLAN. This means that if an individual MAC address is learned in one VLAN, that learned
information is only used in forwarding decisions taken for that address by that VLAN.
In this case, the same MAC address can be used in different VLANs, as each filtering data base can
contain an entry for that MAC address. This way, the Thomson Gateway can be connected to the same
device via different connections.
Shared VLAN Learning/Independent VLAN Learning
Creating a new VLAN learning constraint
To create a new VLAN learning constraint, use the command
Following two parameters must be specified:
Type: the type of the VLAN learning constraint. This type can be set to:
Shared
Independent
Vlan: the VLAN to which the constraint belongs.
Depending on the selected type, one of the following parameters must be specified:
Vlan2: if the type is set to shared, this parameter indicates a second VLAN. As a result, Shared VLAN
Learning is used between the VLANs identified by the pair of VLANs (Vlan and Vlan2).
Isi: if the type is set to independent, this parameter indicates the Independent Set Identifier (ISI). The ISI is
a number within the range from 0 through 32. As a result, Independent VLAN Learning is used between
all VLANs with the same ISI.
12
dynamic entries
in the filtering data base(s) of the Ethernet bridge.
(SVL): only one filtering data base is supported, shared by all VLANs. This means
(IVL): multiple filtering data bases are supported and each data base is used
:eth bridge rule
(SVL/IVL): this is a combination of SVL and IVL.
:eth bridge rule add
.
.
E-DOC-CTC-20080229-0001 v1.0
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