Spanning Tree (Ieee 802.1D); Figure 9-23 Stp-Blocked Path; Table 9-4 Port Settings - Cisco ONS 15327 User Documentation

Spanning Tree (IEEE 802.1D)

To put a port in a VLAN, click the port and choose either Tagged or Untag.
Step 3
settings.
Table 9-4
Setting
--
Untag
Tagged
If a port is a member of only one VLAN, go to the row of that VLAN and choose Untag from the Port
column. Choose -- for all the other VLAN rows in that Port column. The VLAN with Untag selected can
connect to the port, but other VLANs cannot access that port.
If a port is a trunk port, it connects multiple VLANs to an external device, such as a switch, that also
supports trunking. A trunk port must have tagging (IEEE 802.1Q) enabled for all VLANs that connect
to that external device. Choose Tagged for all VLAN rows that need to be trunked. Choose Untag for
each of the VLAN rows in the trunk port column that do not need to be trunked, for example, the default
VLAN. Each Ethernet port must attached to at least one untagged VLAN.
After each port is in the appropriate VLAN, click Apply.
Step 4
If Tagged is chosen, the attached external devices must recognize IEEE 802.1Q VLANs.
Note
9.6 Spanning Tree (IEEE 802.1D)
The Cisco ONS 15327 operates Spanning Tree Protocol (STP) according to IEEE 802.1D when an
Ethernet card is installed. STP operates over all packet-switched ports including Ethernet and SONET
ports. On Ethernet ports, STP is disabled by default but may be enabled with a check box under the
Provisioning > Port tabs at the card-level view. On SONET interface ports, STP activates by default and
cannot be disabled.
The Ethernet card can enable STP on the Ethernet ports to allow redundant paths to the attached Ethernet
equipment. STP spans cards so that both equipment and facilities are protected against failure.
STP detects and eliminates network loops. When STP detects multiple paths between any two network
hosts, STP blocks ports until only one path exists between any two network hosts
single path eliminates possible bridge loops. This is crucial for shared packet rings, which naturally
include a loop.

Figure 9-23 STP-blocked path

Cisco ONS 15327 User Documentation, R3.3
9-26
Port Settings
Description
A port marked with this symbol does not belong to the VLAN.
The ONS 15327 tags ingress frames and strips tags from egress frames.
The ONS 15327 handles ingress frames according to VLAN ID; egress frames
do not have their tags removed.
Primary path (forwarding)
Redundant path (blocked)
Chapter 9 Ethernet Operation
Table 9-4 shows valid port
(Figure 9-23). The
June 2002