Chapter 9 Management Network Connectivity

9.7.4 OSI Routing

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When you provision an ONS 15600 for a network with NEs that use both the TCP/IP and OSI protocol stacks, you will provision it as one of the following:

•Intermediate System Level 1—The ONS 15600 performs OSI IS functions. It communicates with IS and ES nodes that reside within its OSI area. It depends upon an IS L1/L2 node to communicate with IS and ES nodes that reside outside its OSI area.

•Intermediate System Level 1/Level 2—The ONS 15600 performs IS functions. It communicates with IS and ES nodes that reside within its OSI area. It also communicates with IS L1/L2 nodes that reside in other OSI areas. This option should not be provisioned unless the node is connected to another IS L1/L2 node that resides in a different OSI area. The node must also be connected to all nodes within its area that are provisioned as IS L1/L2.

9.7.4.1End System-to-Intermediate System Protocol

ES-IS is an OSI protocol that defines how ESs (hosts) and ISs (routers) learn about each other. ES-IS configuration information is transmitted at regular intervals through the ES and IS hello messages. The hello messages contain the subnetwork and network layer addresses of the systems that generate them.

The ES-IS configuration protocol communicates both OSI network layer addresses and OSI subnetwork addresses. OSI network layer addresses identify either the NSAP, which is the interface between OSI Layer 3 and Layer 4, or the NET, which is the network layer entity in an OSI IS. OSI SNPAs are the points at which an ES or IS is physically attached to a subnetwork. The SNPA address uniquely identifies each system attached to the subnetwork. In an Ethernet network, for example, the SNPA is the 48-bit MAC address. Part of the configuration information transmitted by ES-IS is the NSAP-to-SNPA or NET-to-SNPA mapping.

9.7.4.2 Intermediate System-to-Intermediate System

IS-IS is an OSI link-state hierarchical routing protocol that floods the network with link-state information to build a complete, consistent picture of a network topology. IS-IS distinguishes between Level 1 and Level 2 ISs. Level 1 ISs communicate with other Level 1 ISs in the same area. Level 2 ISs route between Level 1 areas and form an intradomain routing backbone. Level 1 ISs need to know only how to get to the nearest Level 2 IS. The backbone routing protocol can change without impacting the intra-area routing protocol.

Cisco ONS 15600 Reference Manual, R7.2

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Cisco Systems ONS 15600 manual End System-to-Intermediate System Protocol, Intermediate System-to-Intermediate System
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ONS 15600 specifications

Cisco Systems ONS 15600 is a highly versatile optical networking platform designed to meet the demands of modern telecommunications and data services. This multiservice edge platform supports various transmission mediums and offers a wide array of features that enable efficient data transport. Ideal for service providers and large enterprises, the ONS 15600 is engineered to provide scalable and reliable optical transport solutions.

One of the notable features of the ONS 15600 is its capability to support multiple protocols, including SONET/SDH, Ethernet, OTN, and legacy TDM services. This flexibility allows users to tailor their networks according to specific service requirements while ensuring interoperability with existing infrastructure. The platform is designed to facilitate seamless service migration, accommodating both legacy and next-generation services.

The modular architecture of the ONS 15600 enhances its scalability. It allows for easy expansion by incorporating additional line cards or interface modules without requiring significant downtime. This modularity ensures that service providers can evolve their networks over time, responding to increasing bandwidth demands and new service offerings with ease.

Incorporating advanced technologies, the ONS 15600 employs Dense Wavelength Division Multiplexing (DWDM), significantly increasing the capacity of fiber networks by allowing multiple signals to be transmitted simultaneously over a single optical fiber. This capability helps to optimize fiber utilization and reduce operational costs. In addition, the platform supports Optical Transport Network (OTN) for improved error detection and correction, contributing to higher reliability and performance.

Another key characteristic of the ONS 15600 is its robust management capabilities. The platform can be managed through Cisco's Optical Networking Manager (ONM), providing a centralized interface for network configuration, monitoring, and troubleshooting. This enhances operational efficiency and minimizes downtime, allowing service providers to focus on delivering quality services to their customers.

The ONS 15600 also prioritizes security, offering various features like encryption and access control to safeguard sensitive data during transmission. With its combination of scalability, flexibility, and security, the Cisco ONS 15600 stands out as a reliable choice for organizations looking to enhance their optical networking capabilities while meeting the evolving demands of the digital landscape. Its commitment to quality and performance makes it a cornerstone of modern optical networks.
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