HP Cluster Platform Interconnects v2010 Using InfiniBand for a Scalable Comput - Page 4

Figure 3. InfiniBand link types 1x Link 4x Link (1 send channel 1 receive channel each using differential voltage or fiber optic signaling) 12x Link The host channel adapter (HCA) can divide (multiplex) each link into a set of virtual lanes, similar to highway lanes (Figure 4). Using virtual lanes, an InfiniBand link can share bandwidth between various sources and targets simultaneously. For example, if the HCA divides a 10 Gb/s link into five virtual lanes, each lane has a bandwidth of 2 Gb/s. The InfiniBand architecture defines a virtual lanemapping algorithm to ensure inter-operability between end nodes that support different numbers of virtual lanes. Figure 4. InfiniBand virtual lane operation Sources Targets Overhead in data transmission limits the maximum data bandwidth per link to a peak of 80 percent of the signal rate. However, InfiniBand's switched fabric design lets bandwidth scale as you add links and nodes. 4