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Cisco ONS 15454 Installation and Operations Guide
78-13453-01
Chapter5 SONET Topologies
Unidirectional Path Switched Rings
Step 7 Disable the ring on the current node:
a. Click the Provisioning > Ring tabs.
b. Highlight the ring and click Delete.
c. On the confirmation message, confirm that this is the ring you want to delete. If so, click Yes.
Step 8 If an OC-N card is a timing source, select the Provisioning > Timing tabs and set timing to Internal.
Step 9 Place the ports on the card out of service:
a. Double-click the card.
b. On the Provisioning > Line tabs in the Status section, choose Out of Service for each port.
Step 10 Physically remove the card.
Step 11 Insert the card into its new slot and wait for the card to boot.
Step 12 To delete the card from its former slot, right-click the card in node view and select Del ete from the list
of options.
Step 13 Place the port(s) back in service:
a. To open the card, double-click or right-click the card and select Open.
b. Click the Provisioning tab.
c. From Status choose In Service.
d. Click Apply.
Step 14 Follow the steps described in the “Setting Up BLSRs” section on page5-10 to reenable the ring using
the same cards (in their new slots) and ports for east and west. Use the sam e BL SR Rin g I D a nd Node
ID that was used before the trunk card was moved.
Step 15 Recreate the circuits that were deleted. See the “Create an Automatically Routed Circuit” procedure on
page 6-2 for instructions.
Step 16 If you use line timing and the card you are moving is a timing reference, reenable the timin g parameters
on the card. See the “Set up ONS 15454 Timing” procedure on page 3-14 for instructions.
5.3 Unidirectional Path Switched Rings
UPSRs provide duplicate fiber paths around the ring. Working traffic flows in one direction and
protection traffic flows in the opposite direction. If a problem occurs in the working traffic path, th e
receiving node switches to the path coming from the opposite direction.
CTC automates ring configuration. UPSR traffic is defined within the ONS 15454 on a circuit-by-circuit
basis. If a path-protected circuit is not defined within a 1+1 or BLSR line protection scheme and path
protection is available and specified, CTC uses UPSR as the defa ult.
Figure 5-20 shows a basic UPSR configuration. If Node ID 0 sends a signal to Node ID 2, t he wo rkin g
signal travels on the working traffic path through Node ID 1. The same signal is also sent on the prot ect
traffic path through Node ID 3. If a fiber break occurs (Figure 5-21), Node ID 2 switches its active
receiver to the protect signal coming through Node ID 3.
Because each traffic path is transported around the entire ring, U PSRs are best su ited for net works where
traffic concentrates at one or two locations and is not widely distributed. UPSR capacity is equal to its
bit rate. Services can originate and terminate on the same UPSR, or they can be passed to an adjacent
access or interoffice ring for transport to the service-terminating location.