Ethernet switch chip start-up Greenfield Networks this week announced it has completed a third round of venture capital funding.The company snagged $21.5 million in this round, bringing Greenfield\u2019s total to $48 million. A new investor is JPMorgan Partners, adding to the investments from Sequoia Capital, Global Catalyst Partners and Walden International.Greenfield in May at the NetWorld+Interop trade show unveiled an edge chassis reference design with full IPv6 support, packing 128 ports of Gigabit Ethernet in a box 5 rack units high. Control-plane software from different vendors is supported, to enable routing of a variety of protocols.Greenfield\u2019s approach is to create silicon that can be used in both edge and core, with the key benefit being full support for IPv6. The company\u2019s chips also have scalable MAC, route and classification tables. They\u2019re intended for service providers as well, supporting MPLS, stacked virtual LANs, VPNs and IP tunneling.QoS features include large packet classification tables, per-port or flow-rate limiting and per-queue traffic shaping.The primary products include a packet engine, a shared memory fabric, and an intelligent multiplexer for building chassis linecards. Other manufacturers would use the chips and the reference design as they build their own switching and routing systems. Greenfield is one of many small companies that have gotten into the business of developing silicon for network hardware, so that system vendors can mix and match hardware and software when creating a total system.Greenfield says it will use the new investment capital \u201cto aggressively pursue additional market opportunities and accelerate expansion plans.\u201d The company says it expects to become profitable next year.