A pair of Longbow C400 devices communicates over 4, 2 or 1 10 Gbits/second WAN light paths at distances of up to 1,600km (1,000 miles), connecting locally to InfiniBand LAN infrastructure through 4X QDR, DDR or SDR InfiniBand (IB) ports. The Longbow C400 series devices report as two-port InfiniBand switches to the subnet manager - the fabrics at each end-point location unify into a single subnet. Longbow C400 devices perform buffer credit extension at the link level. When combined with up to four 10Gbits/second serialized optical data streams at the physical layer, they allow InfiniBand to reach much farther than any other technology. Since C400 series devices use a proprietary optical WAN encoding, they must be deployed in pairs, connected by direct light paths.

• Port 1 (LAN) QSFP supports 4X QDR, DDR and SDR InfiniBand LAN interfaces.
• Port 2 (WAN) SFP+ supports four 10Gbits/second light paths.
• Due to skew constraints between parallel optical WAN channels, it is recommended that C400s are deployed with CWDM WAN solutions, such as Obsidian's Rainbow C8 or Rainbow D9 devices, which were designed to carry multiple 4X QDR InfiniBand connections across a single fiber pair. C400 gracefully degrades InfiniBand port speeds if 10Gbits/second WAN channels are lost, for example QDR will degrade to DDR if one or two WAN links fail, and DDR to SDR if only a single WAN circuit remains.
• Optics modules: type: SFP+ module (quad transceiver cage).
• Connector: Duplex-LC.
• Wavelength: (850, 1,310, 1,550nm, CWDM or DWDM; user provided).
• Raw bit rate: 10.3125 Gbits/second per transceiver.
• Optical interface: node type: two-port switch.
• Physical layer: SFP+ specification.
• Payload: IB link proprietary encoding.
• Raw bandwidth: 40.0 Gbits/second max (QDR mode).
• BER control: integrated high-gain FEC.
• InfiniBand interface: connector: IB QSFP 4X, QDR at 32 Gbits/second (payload).
• Node type: two-port switch.
• Physical layer: InfiniBand architecture v1.2.
• Subnet manager agent: integrated InfiniBand architecture v1.2.
• VLs: 1 data and 1 management.
• Port-to-port latency: 350ns (small packet store-and-forward).
• Longbow C400 series ordering codes: C400: base chassis hardware with 300m range enabled without optics.
• C400 license keys unlock required QDR link ranges: 10km, 40km, 80km, 400km, 1,600km link ranges are available as either annual or lifetime licenses.