Cisco ONS 15200 - Manual (Page 40)

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Cisco ONS 15200 Product Description
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Chapter 4 Operation, Administration, and Maintenance
Network Management Overview
An internal data bus, also called a controller area network (CAN) bus, connects an NCB module to
different CLIP modules of the ONS 15252 MCU. You can extend this data bus over several co-located
network elements (ONS 15252 MCUs or ONS 15201 SCUs) to a larger logical unit. The ONS 15201
SCU uses the same data bus as the MCU. Normally one CAN bus connects all ONS 15200 equipment
located at one site.
An overhead channel exists and is implemented as a base band modulation on the individual DWDM
optical channels. Two end-points of a channel communicate using this low frequency signal, called QPP
(Qeyton Proprietary Protocol). The QPP specification defines the physical and link layer protocols for
communication.
Any CLIP module controlled by an NCB must not be more than two QPP hops away from that NCB. If
the CLIP is further away from the NCB, you must install additional NCB modules.
Release 1.1 allows you to configure up to two active NCBs as managers of any CLIP in a network. To
manage the CLIP, it must be no further than two CAN and two QPP hops away from the NCB. Any NCB
in a network that is not provisioned as an active manager of a CLIP can still inventory the CLIP.