REVIEW DRAFT—CISCO CONFIDENTIAL
14-13
Cisco ONS 15454 SDH Reference Manual, R5.0
April 2008
Chapter14 Ethernet Operation
14.3.3 E-Seri es VLAN Support
Note To enable flow control between an E-Series in port-mapped mode and a SmartBits test set, manually set
bit 5 of the MII register to 0 on the SmartBits test set. To enable flow control between an E-Series in
port-mapped mode and an Ixia test set, select Enable the flow control in the Properties menu of the
attached Ixia port.
14.3.3 E-Series VLAN Support
Users can provision up to 509 VLANs per network with the CTC software. Specific sets of ports define
the broadcast domain for the ONS 15454 SDH. The definition of VLAN ports includes all Ethernet and
packet-switched SDH port types. All VLAN IP address discovery, flooding, and forwarding is limited to
these ports.
The ONS 15454 SDH IEEE 802.1Q-based VLAN mechanism provides logical isolation of subscriber
LAN traffic over a common SDH transport infrastructure. Each subscriber has an Ethernet port at each
site, and each subscriber is assigned to a VLAN. Although the subscriber’s VLAN data flows over shared
circuits, the service appears to the subscriber as a private data transport.
Note Port-mapped mode does not support VLANs.
The number of VLANs used by circuits and the total number of VLANs available for use appears in CTC
on the VLAN counter.
14.3.4 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 15454 SDH works with Ethernet devices that support IEEE 802.1Q and those that do not
support IEEE 802.1Q. If a device attached to an ONS 15454 SDH Ethernet port does not support
IEEE 802.1Q, the ONS 15454 SDH uses Q-tags internally only. The ONS 15454 SDH associa tes these
Q-tags with specific ports.
With Ethernet devices that do not support IEEE 802.1Q, the ONS 15454 SDH 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 IE EE 8021.Q 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 14-12 illustrates Q-tag
use only within an ONS network.