StarFabric Technology
StarFabric – a network of PCI busses
PCI/CPCI bus and connect it to other PCI/CPCI systems or extension boards, and that up to a distance of up to 13 meters.
For purposes of data transfer via StarFabric, the bridge converts the parallel PCI data traffic to a serial format.
A connection between two nodes is called a link. Such a link consists of separate transmit and receive lines and can reach a transfer rate of 2.5-Gbit in full duplex mode with a „single link“ connection.
If needed, a second cable pair can be connected. Then the two links can be operated
- separately to form a redundant connection, or
- in parallel to obtain a bidirectional 5-Gbit connection.
Each StarFabric board is equipped with two links that are brought out via four RJ45 jacks, to which common network patch cables (cat5 or better) can be connected. The maximum permissible distance between two nodes is 13 m. The cable lengths of the transmit and receive lines of a link must always be identical. The cable from RX is to be connected to TX at the other end, and the cable from TX to RX at the other end.
Switched Fabric Network Topology
StarFabric is based on a switched fabric network topology. This is a collection of switchable pointto-point connections. In such a network, all stations are partners with equal rights, and each one can communicate with any other directly or via a switch. The advantage of a switched fabric is that the stations in the network do not need to share the bandwidth.
Each node in the network stores all existing nodes and paths. The routing-capable StarFabric protocol can determine the shortest path to a target node. When a path fails, an alternative path to the desired target node can be quickly calculated.
Up to 7 switches can be connected in series. In this star-shaped network, up to 1000 end nodes can be cascaded as desired, thereby implementing redundant networks.
A switched fabric network always consists of a root and at least one leaf. The root initiates the assignment of unique addresses called FIDs (fabric identifiers) to the leaves. Hartmann THE Bridge cards can be configured as root or leaf cards via switches.
When building networks with the StarFabric technology, a distinction is made between the transparent and the nontransparent mode.
Transparent mode
In the transparent mode, a The Bridge card functions like a simple PCI-to-PCI bridge and is detected as one by the BIOS when booting.
No additional drivers for the operating system are needed for this mode.
The bridge function of the StarFabric permits the PCI/CPCI bus to be extended beyond the limits of the computer since the CPU and the BIOS of the host PC in the transparent mode do not differentiate between a local or a remote PCI card.
Furthermore, StarFabric switches can be used to build a network of individual PCI bus segments that can be cascaded to any level desired and size of which is limited by the address space of the host PC only.
Setup of a transparent network
- Installation of the root card (device slot board)
Install the preconfigured root card in the host PC. The installed root card permits the BIOS to detect all PCI cards in the PCI bus segments connected via the StarFabric network. When booting the first time after root card installation, the Windows plug and play function detects the card as an “other PCI bridge device” and prompts you to install the driver. The driver installation can be omitted without sacrificing any functionality when the transparent mode is used. The host PC must be shut down and restarted for the subsequent network setup. - Installation of leaf cards (system slot boards) as necessary
A preconfigured leaf card must be installed in each of the external PCI/CPCI racks. This leaf card serves as the master bus in the bus segment in question. If an extension board is used as the system slot board, this step is omitted. - Setup of the StarFabric network
To set up the network, all THE Bridge cards, extension boards and StarFabric switches must be wired via the links, i. e. they must be interlinked.
Please note: The cable lengths of the transmit and receive lines of a link must always be identical.
The cable from RX is to be connected to TX at the other end, and the cable from TX to RX at the other end. - System startup
When starting up a StarFabric network in transparent mode, you must make sure that all connected racks are switched on before the host PC. Otherwise the BIOS of the host PC cannot detect the additional PCI cards.
Once the host PC has been switched on, the yellow link LEDs of the jacks in use must be continuously lit. If this is not the case, verify that each TX jack is connected to an RX jack at the other end.
Nontransparent mode
The gateway function of the StarFabric is used to establish the data traffic to other fabric systems via alternative routing methods. In the nontransparent mode, each node consists of a PC or a CPU. To operate such a network, the bridge function must be disabled on all leaf cards.
To operate a StarFabric network in the nontransparent mode, installation of the driver for the operating system in question is mandatory.
Hartmann Elektronik provides the StarFabricCom library for StarFabric software developments supporting fast data transfer in the nontransparent mode. This library represents an API (Application Programming Interface), which essentially implements a client/server-controlled data exchange via a „virtual“ shared memory. This API is based on the StarGen FPL library, which can be obtained as part of StarGen SDK from StarGen/Dolphin after signing a „Non Disclosure Agreement“. For further information, please visit Dolphin’s web page (www.dolphinics.com).
To support more specific developments, the FPL library includes functions and mechanisms that can be used to implement data transfer in nontransparent mode:
Routing methods
- Path Routing
This mechanism routes data to one recipient only. The path is defined by the StarFabric IC. The shortest path is selected by default. - Multicast Routing
Here, data can be sent to several recipients at the same time. Multicast groups are defined as recipients for this purpose.
Traffic classes
To enable prioritized data transfer across the network, it is possible to assign priority or traffic classes.
Bandwidth control
An expected bandwidth can be reserved for isochronous and multicast transfers before the beginning of the data transfer.
Fault-tolerant strategies
Redundant configurations can be used to increase fail safety. In the event a path fails, the system automatically determines a functional path and transfers the data via this path. For example, a second switch can be implemented for redundancy.
Credit-based technique
The StarFabric only transfers data when the recipient can receive the data. This credit-based technique prevents collisions and avoids unnecessary loads in the StarFabric.
Synchronization of data
Network stations with connections that are operable are synchronized.
Startup of a nontransparent network
- Installation of root card (device slot board)
Install the preconfigured root card in the host PC.
The installed root card permits the BIOS to detect all PCI cards in the PCI bus segments connected via the StarFabric network.
When booting the first time after root card installation, the Windows plug and play function detects the card as an “other PCI bridge device” and prompts you to install the driver. Once you have installed the driver, the host PC must be shut down and restarted for the subsequent network setup. - Installation of leaf cards (system slot boards)
A preconfigured leaf card must be installed in each of the PCs that are connected.
When booting the first time after leaf card installation, the Windows plug and play function detects the card as an “other PCI bridge device” and prompts you to install the driver. Once you have installed the driver, the computer must be shut down and restarted for the subsequent network setup. - Setup of the StarFabric network
To set up the network, all THE Bridge cards and StarFabric switches must be wired via the links, i.e. they must be interlinked.
Please note: The cable lengths of the transmit and receive lines of a link must always be identical.
The cable from RX is to be connected to TX at the other end, and the cable from TX to RX at the other end. - Network startup
When starting up a StarFabric network in nontransparent mode, you must make sure that all the racks connected are switched on before the host PC. The host PC is responsible for StarFabric network arbitration and assigns a unique Fabric Identifier address (FID) to all StarFabric devices connected.
Several settings must be made in the registration file for the use of the StarFabric in nontransparent mode.