Browse Prior Art Database

Cabling harness to extend mesh connection to 9 systems. Disclosure Number: IPCOM000130146D
Original Publication Date: 2005-Oct-13
Included in the Prior Art Database: 2005-Oct-13
Document File: 4 page(s) / 161K

Publishing Venue



Interconnecting multiple systems can be done simply and cheaply by directly linking each server to every other server. But, the cabling can be difficult to implement as the number of systems increases. And, for systems that provide multiple different types of connectors, it may be impossible to utilize every available connector to achieve the largest possible interconnected cluster. Scaling beyond the number of systems that can be directly connected usually adds additional cost in the form of an external switch, or reduces performance by forcing multiple system-system communications paths to share a physical. A prior article (insert reference) describes a new cabling harness which fully utilizes a single connector containing three links to create a four system cluster. This article describes an additional new cable harness that would allow direct interconnection of a seven node cluster when two of these same three link connectors are available on each node.

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Page 1 of 4

Cabling harness to extend mesh connection to 9 systems.

    The InfiniBand Standard (ref: ) defines a 4x link and a specific 4x copper connector which is used for almost all current InfiniBand box to box connections. The standard also defines a 12x link and a specific 12x copper connector which bundles the equivalent of three 4x links into a single connector. 12x connections are just starting to appear in products. These 12x connections are intended to provide higher bandwidth connections, while requiring less panel space and cabling than three 4x connections in parallel would require. (ref: IBM eServer BladeCenter and Topspin InfiniBand Switch Technology RedPaper, IBM Form Number: REDP-3949-00 - )

    Current 12x implementations also support configuring the 12x port as three distinct 4x ports. To utilize the 12x connector, a standard 12x IB cable could be used to connect to one other system. To utilize the three ports to connect to three other systems, a special cable is required that has a single 12x connector at one end and three 4x connectors at the other end. (ref: IBM p/n 26R0816 &storeId=1&langId=-1&catalogId=-840 )

But, if all of the connectors are used to provide one link from the first system to each of the other three, there is no ability to provide direct links between the 2nd and 3rd, 3rd and 4th, and 3nd and 4th systems. Two 4x links on each of the other three systems are not being utilized.

    In a prior article ( insert reference ) a new cable harness was described that provides full mesh connectivity, every system directly connected to every other system, between four systems, through the four 12x ports.


Page 2 of 4

    To extend this direct connection topology, a second switch module can be installed in each BladeCenter chassis, doubling the number of external connectors. Just utilizing two 12x ports per system, a seven system configuration can be created. First, 4 systems are connected with the previously described cable assembly. Then, one of the four systems is fully connected to three additional systems through a second of the previously described cables. This leaves one of the two 12x connectors still unused on all but the first system. (Th...