E-Series Q-Tagging (Ieee 802.1Q); Figure 23-15 Q-Tag Moving Through Vlan - Cisco ONS 15454 SDH Configuration Manual

E-Series Q-Tagging (IEEE 802.1Q)

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 different
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 support 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
within an ONS network.
Figure 23-15
Example 1.
The ONS node uses a
Q-tag internally to deliver
the frame to a specific VLAN.
Example 2.
The ONS node receives
a frame with a Q-tag
and passes it on.
The ONS node uses the Q-tag attached by the external Ethernet devices that support IEEE 802.1Q.
Packets enter the ONS network with an existing Q-tag; the ONS node uses this same Q-tag to forward
the packet within the ONS network and leaves the Q-tag attached when the packet leaves the ONS
Cisco ONS 15454 and Cisco ONS 15454 SDH Ethernet Card Software Feature and Configuration Guide, R8.0
23-18
Q-tag Moving Through VLAN
No tag
Q-tag
Data Flow
Q-tag
The receiving ONS node
removes the Q-tag
and forwards the frame
to the specific VLAN.
Q-tag
The receiving ONS node
receives a frame with a
Q-tag and passes it on.
Chapter 23 E-Series and G-Series Ethernet Operation
Figure 23-15 illustrates Q-tag use only
No tag
Q-tag