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Ethernet Card Software Feature and Configuration Guide, R7.2
January 2009
Chapter 23 E-Series and G-Series Ethernet Operation
E-Series Q-Tagging (IEEE 802.1Q)
Figure 23-14 Edit Circuit Dialog Box Featuring Available VLANs
E-Series Q-Tagging (IEEE 802.1Q)
E-Series cards in single-card and multicard mode support IEEE 802.1Q. IEEE 802.1Q allows the same
physical port to host multiple IEEE 802.1Q VLANs. Each IEEE 802.1Q VLAN represents a di fferent
logical network. E-Series cards in port-mapped mode transport IEEE 802.1Q tags (Q-tags), but do not
remove or add these tags.
The ONS node works with Ethernet devices that support IEEE 802.1Q and those that do not support
IEEE 802.1Q. If a device attached to an E-Series Ethernet port does not sup port IEEE 802.1Q, the ONS
node uses Q-tags internally only. The ONS node associates these Q-tags with specific ports.
With Ethernet devices that do not support IEEE 802.1Q, the ONS node takes non-tagged Ethernet frames
that enter the ONS network and uses a Q-tag to assign the packet to the VLAN associated with the ONS
network’s ingress port. The receiving ONS node removes the Q-tag when the frame leaves the ONS
network (to prevent older Ethernet equipment from incorrectly identifying the IEEE 802.1Q packet as
an illegal frame). The ingress and egress ports on the ONS network must be set to Untag for the removal
to occur. Untag is the default setting for ONS ports. Example 1 in Figure 23-15 illustrates Q-tag use only
within an ONS network.