Specifications

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Cisco ONS 15530 Planning Guide
OL-7708-01
Chapter 2 Protection Schemes and Network Topologies
Supported Topologies
Ring Topologies
In a ring topology, client equipment is attached to three or more Cisco ONS 15530 systems, which are
interconnected in a closed loop. Channels can be dropped and added at one or more nodes on a ring.
Rings have many common applications, including providing extended access to SANs (storage area
networks) and upgrading existing SONET rings. In the cases where SONET rings are at capacity, the
SONET equipment can be moved off the ring and connected to the Cisco ONS 15530 systems. Then the
SONET client signals are multiplexed and transported over the DWDM link, thus increasing the capacity
of existing fiber.
Hubbed Ring
A hubbed ring is composed of a hub node and two or more add/drop or satellite nodes. All channels on
the ring originate and terminate on the hub node, which is either a Cisco ONS 15540 ESP shelf, a
Cisco ONS 15540 ESPx shelf, or Cisco ONS 15530 shelves configured in a multiple shelf node. At
add/drop nodes certain channels are terminated (dropped and added back) while the channels that are not
being dropped (express channels) are passed through optically, without being electrically regenerated.
Channels are dropped and added in bands. Figure 2-16 shows a four-node hubbed ring in which
bands ABC terminate on node 1. Nodes 1 and 2 communicate using band A, nodes 1 and 3
communicate using band B, and nodes 1 and 4 communicate using band C.
Figure 2-16 Hubbed Ring Topology Example
For example configurations of hubbed ring topologies, see Chapter 6, “Example Shelf Configurations
and Topologies.”
Band C Band A
Node 1 (hub)
Node 3
Node 2Node 4
Band B
Bands ABC
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