Lucent's new core

Lucent Technologies last week announced shipment of its new core multiservice switch. Unlike competitive offerings based on ATM cell switches, Lucent's TMX 880 is a packet switch based largely on the NX64000 router obtained through the company's 1999 acquisition of Nexabit Networks. Lucent claims to have added so many ATM switching features to the box, however, that to characterize it as a router would be inaccurate.

Lucent opted for a packet switch because a cell-based architecture is inefficient for packet traffic and may be shortsighted given the expected growth of IP.

One of the key features of the TMX 880, and one that may aid carriers in migrating their ATM cores to IP and Multi-protocol Label Switching (MPLS), is a capability Lucent calls Fluid Signaling. Fluid Signaling is the basis for integrating the control planes of the ATM and IP/MPLS domains in a multiservice network, Lucent says.

Fluid Signaling maps bidirectional ATM permanent virtual circuits into two unidirectional MPLS label-switched paths, and vice versa. It maintains quality-of-service, Lucent claims, by translating ATM resource requests to MPLS resource requests, and proxies ATM OAM&P flows through the MPLS domain to maintain service monitoring and integrity.

Though Lucent claims Fluid Signaling is based on standards such as ATM's PNNI, the company has submitted its VC-to-LSP mapping and OAM&P proxy techniques to standards bodies for consideration as an industry standard way to integrate control planes. The TMX 880 also supports Lucent's proprietary VNN signaling so the company's installed base of GX 550 and CBX 500 switch users can participate in the TMX 880 core.

One feature the TMX 880 will not support is an OC-192c ATM trunk interface. Segmentation and reassembly of cells at greater than OC-48 is "very challenging," Lucent says, and there's no market momentum for OC-192c ATM.

The TMX 880 will support OC-192c packet-over-SONET links on the trunk side. The TMX 880 is shipping in controlled release now. It is in lab trials with service providers Lucent declined to identify.

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