White Paper
Cisco® ONS 15454 SDH solutions from Cisco Systems® can be used in a multichassis configuration to offer extended cross-connect capacity. This document describes this type of application and provides technical information about it.
Introduction
The carrier-class Cisco ONS 15454 SDH Multiservice Provisioning Platform (MSPP) solution offers unique benefits to service providers and end users, given its capabilities to support data, storage, time-division multiplexing (TDM), and dense wavelength-division multiplexing (DWDM) services on a single platform - all very efficiently and cost effectively.
For TDM applications, the Cisco ONS 15454 SDH offers add/drop multiplexer (ADM) and broadband digital cross-connect (BBDXC) capabilities that allow SDH virtual containers (VCs) to be cross-connected and groomed to optimize the use of available network resources. This function is performed using cross-connect cards (part number XC-VXC-10G) in the Cisco ONS 15454 SDH chassis. This cross-connect card works in a redundant configuration (1 + 1) and offers nonblocking cross-connect capacity at the VC-4 level, allowing it to have full access to all TDM capacity available in each slot at the high-order virtual container.
In customer edge applications and network designs, the multiservice capacity of the Cisco ONS 15454 allows a decentralized grooming capacity. The Cisco ONS 15454 SDH solution allows grooming, data traffic aggregation, and transport optimization to the edge of customer networks, avoiding the need for a large cross-connection platform in the central office.
Customer edge applications may require configurations that allow more cross-connect capacity than what is supported on a single Cisco ONS 15454 SDH chassis with cross-connect cards. As this document details, deploying multichassis Cisco ONS 15454 SDH configurations allows service providers or other end users to extend the cross-connect capacity at a given site.
Card Architecture
The cross-connect card offers the following capacity:
• 384 x 384 VC-4s (nonblocking)
• 384 x 384 VC-3s
• 2016 x 2016 VC-12s and 2688 x 2688 VC-11s
Figure 1 shows that the Cisco ONS 15454 SDH solution has 12 service slots for tributary or trunk interfaces. Eight of the slots (slots 1-4 and 14-17) support up to 2.5-Gbps speeds and are referred to as multiservice slots. The remaining 4 service slots (5-6 and 12-13) support up to 10-Gbps speeds and are referred to as high-speed slots.
This cross-connect capacity allows customers to have full access at VC-4 layer to all high-speed slots, as well as to multiservice slots.
Figure 1
Cisco ONS 15454 SDH Cross-Connect Card Architecture
Multichassis Solution for Extended Cross-Connect Capacity
As noted previously, customer edge applications require configurations that allow more cross-connect capacity than what is supported on a single Cisco ONS 15454 SDH chassis with the cross-connect cards. A multichassis solution can be used to allow extended cross-connect capacities, increasing the number of slots available in the solution to allow more services in the network.
Figure 2
Multichassis Cisco ONS 15454 SDH Configuration for Extended Cross-Connect Capacity
Figure 2 shows one example of a multichassis Cisco ONS 15454 SDH configuration. Assuming that all Cisco ONS 15454 SDH chassis have the same cross-connect capacity, whenever two or more chassis are interconnected using any bit rate (STM-N interface), the total cross-connect capacity of the site - or of the multichassis solution - is increased according to the following guideline:
TXC Site = N x XC15454 SDH - XCINTERCONNECTION
where:
TXC Site = Total cross-connect capacity of the site
N = Number of Cisco ONS 15454 SDH chassis
XC15454 SDH = Cross-connect capacity of a single Cisco ONS 15454 SDH configuration
XCINTERCONNECTION = Cross-connect capacity used for interconnecting the chassis in the site
Applying this guideline to the example shown in Figure 2, the cross-connect capacities that can be achieved using 2.5- or 10-Gbps interconnections in a two-chassis configuration are presented in Table 1.
Table 1. Cross-Connect Capacities That Can Be Achieved in Multichassis Cisco ONS 15454 SDH Configurations
Table 1 assumes that each Cisco ONS 15454 SDH does low-order virtual container grooming and no low-order cross-connections need to be created for the intersite connections. Also, the speed of the slots used for chassis interconnection must be respected; that is, if STM-64 interconnection is required, the high-speed slots must be used.
The provisioning in this solution is done using the Cisco ONS 15454 SDH Path Protected Meshed Network (based on subnetwork connection protection [SNCP] standard).
Conclusion
As presented in this document, the Cisco ONS 15454 SDH solution can be used in applications that require extended cross-connect capacity by using multiple chassis in a site, interconnected by optical interfaces.
