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Network Services |
CM-100 Packet Transport Switch - Download PDF TDM Services in the Packet Transport Switch - SDH The CM-100 Packet Transport Switch is a carrier-class packet-optimized network element for the transport of Data and TDM services. For TDM services, it supports the transport of VT1.5/VC11, VT2/VC12, STS-1/VC-3, STS-Nc/VC-4-Xc signals (e.g. private line) as circuit emulation over packets (CEP). These services are transported within the same delay, jitter and wander tolerances as in traditional SONET/SDH devices, compliant with ITU-T and Telccordia specifications.
At every TDM user interface module (UIM), a number of Group Termination Points (GTP) are defined on the network side. This creates a number of virtual ports, effectively enabling the cross-connection of multiple user-side DS1/E1/VT signals to a network-side fractional STS-1/VS-3 (a fractional STS-1/VS-3 carries only a set of utilized VT/VC within an STS-1/VC3 container). This enables the suppression of unused rows (i.e. idle channel suppression) yielding an efficient use of network capacity and bandwidth conservation.
A packet-based transport NE ("Packet Transport Switch") implementing the CEP scheme, effectively enables non-blocking Distributed Virtual Cross-Connection of TDM signals, as illustrated in Figure 2. The following cross-connect services are supported on the CM-100 Packet Transport Switch:
The CM-100 product line consists of two models having the same dimensions and providing the sam functionality, only varying in the number of fuser interface moddules. The CM-106 supports up to six vertically-aligned UIM/HIM, whereas the CM-110 supports up to ten vertically-aligned UIM/HIM.
Compliance and TDM and Circuit Emulation Standards SONET/SDH Standards
Timing Standards
IETF PWE3 WG Draft Standards
Data services supported in Corrigent's CM-100
User Interface Modules (UIM)
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Corrigent's CEP implementation is consistent with the IETF-draft-ietf-pwe3-sonet-11.txt for Circuit Emulation over Packet (CEP). As illustrated in Figure 1, in this scheme, the payload is broken into 783-byte packets, which corresponds to the size of the SPE. A 4-byte CEP label is then appended to each packet, including indications for AIS, UNEQ, pointer adjustment and sequence number. An MPLS header and VC label are used to identify the virtual circuit and forward the packet to the proper destination.
