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by the access network is assessed to allow the Ethernet aggregation network to be sized and designed as it routes some traffic within the metro area and presents the long-haul traffic onto the IP/MPLS core network. An Integrated Network Planning system plans all of these together, taking into account the specific QoS requirements for the various services riding on the IP and Ethernet networks, as well as the underlying physical optical transport network that carries all of this traffic (actually, it is even more complex, with legacy network technologies and services, as well as VoIP and signaling traffic sharing the network fabric). Traditionally, the planning of each of these "domains" (be they technology, geographic, or even temporal – with planners for various time periods) was done separately, with little information interchange among them. In contrast, a strong, multi-technology, multi-domain Integrated Network Planning system provides a set of plans that automatically mesh into a single, coherent, cost-effective master plan for the next-generation network, avoiding inefficiencies and stranded resources, while assuring sufficient network capacity in the right place, at the right time to support the new services.
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Planning such diversity requires full knowledge of the facility hierarchy within the transport layer. |
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on wavelengths, which are multiplexed into fibers, which are bonded into cables, which are placed in ducts, conduits, holes, or placed on poles and routed within or between central offices. Diversity among the designated primary and backup links within the transport layer must be maintained (at some level) to keep single points of failure from disrupting the transport layer.
Planning such diversity requires full knowledge of the facility hierarchy within the transport layer. This can be done manually, but laboriously, by a transport engineer using a good network resource management (e.g., inventory) system. It can also be planned automatically by an Integrated Network Planning system that has full knowledge of the facility hierarchy and network layout.
But, for most services, this is not good enough. The Integrated Network Planning
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Multi-Layered Backup Planning
The various layers of the network need to be planned to ensure that outages in underlying layers do not cause QoS violations in IP-based services. Integrated Network Planning systems design networks to ensure diversity of the layered transport links and preserve the integrity of backup routes to network failures, to the extent required by the services riding on the IP networks.
The first constraint of a network design involves the underlying transport network, which itself is a layered architecture. It contains interface cards using links, which ride
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system has to ensure that all routes, especially those that require a high-QoS, are diverse among the technology layers.
As an example, when planning for a set of IP/MPLS paths that will carry a high QoS service, planners typically set up diverse paths between the routers (1:1 or 1:N), which are automatically switched into service if a failure occurs. Sophisticated Integrated Network Planning systems automatically provide designs that include knowledge of the underlying transport network that carries these paths. They check that the diverse IP/MPLS paths do not share a transport facility, piece of
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