Grooming

Grooming is the combining of multiple lower speed circuits into a higher speed circuit. VC [Virtual Concatenation] gives service providers additional customer data protocols and data speed options. For example, 28 T-1 circuits can be combined in one T-3 circuit. Grooming is an integral part of optical networks. With photonic switching, network managers can combine transparent trunking, transponder and OEO [Optical-Electrical-Optical] (optical-copper-optical) conversion optimization, banded wavelength routing and trunk grooming to provide new customer services such as variable speed Metro-Ethernet (1, 2.5, 5-10, megabit per second), discussed next.

Sometimes referred to as Grooming Switches, wavelength and sub-wavelength speeds are available directly to multi-vendor switches. These next-generation OOO [Optical-Optical-Optical] switches combine both SONET and DWDM [Dense Wave Division Multiplexing] with OADX [Optical Add/Drop Multiplexing] to simplify carrier provisioning. LCAS [Link Capacity Adjustment Scheme] functions of path overhead for the virtual channel are found in the H4 - multiframe indicator. Each H4 byte contains 4 bits of the first MFI [Multi-Frame Indicator] and 4 bits of the LCAS. A complete LCAS message consists of 16 multiframes. Data payload control (additions/subtractions) are in the H4 byte and the data transport starting with MFI 1 of 8. Generic Framing Procedure is a concept called VC [Virtual Concatenation] in a new protocol called LCAS [Link Capacity Adjustment Scheme] for SONET to transport non-voice (data) across SONET. LCAS-enabled bandwidth on demand supports Ethernet and other data protocols to be able to dynamically change the amount of bandwidth available without incurring a traffic loss event - known as “hitless” reconfiguration. For example, VC [Virtual Concatenation] enables a SONET to transport a 10 megabit link across a VT1.5-6V [VT for Virtual Tributary] or 10.368 megabit link of a full OC-STS-1 or 51.84 megabit link. A 100 megabit link can be transported in a STS-2 or 103.68 megabit link instead of an OC-STS-3 or 155.52 megabit transmission. LCAS can increase/decrease capacity without interrupting traffic flow. LCAS can provide diverse routing by rerouting the traffic to eliminate stranded bandwidth. SONET circuits (provisioned connections) can be moved from one geographical path to another to create space for priority voice services or avoid specific fiber links (runs) that can be removed from service.

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