Skip to main content

IDT PCI Express Gen 3 Switch Demonstration



IDT Gen 3 PCI Express® switches support up to a capacity of 64 lanes, 16 ports and can deliver up to 128 Gigabytes per second (GBps) switching capacity; the highest performance solution in the industry.  Other features include additional protocol enhancements for improved efficiency and reduced power consumption. The PCI Express demonstration showcases 8 Gbps operation with a IDT Gen 3 PCI Express switch.  Presented by Tony Lukassen, Product Manager, Integrated Device Technology, Inc. Learn more at



Today I would like to demonstrate an IDT PCI Express Gen3 switching solution. Before we view the demo, let’s have a brief review on PCI Express switching and the need for Gen3.
PCI Express is a serial protocol that creates a channel for communication between independent components. In many cases, this is communication between a host processor and multiple peripheral devices. Over many years PCI Express has been adopted across many market segments driving the need for more innovative features on a PCI Express switch such as multi route partitioning. 
Examples of applications today utilizing PCI Express switches include enterprise servers and storage arrays, telecom and communications systems, industrial and aerospace, and more. In these applications the most basic common requirement is to provide a mechanism to expand the PCI Express connectivity to many devices. IDT switches are engineered to provide the expansion needed in these systems. 
So, what is PCI Express Gen3? PCI Express Gen3 is the evolution of the PCI Express standard that doubles the performance from the previous generation up to eight gigabit per second. It is important to also note that while Gen3 speeds are supported, so is backwards compatibility to the existing Gen2 and Gen1 speeds. This means that performance driven applications can scale up to Gen3 speeds while maintaining compatibility with the existing infrastructure. 
You may ask, is there more to Gen3 than a speed increase? The simple answer is absolutely. Gen3 switches should also include recent PCI Express protocol extensions that improve overall platform efficiencies resulting in better system performance and reduced power consumption. Several of these new protocol extensions include atomic operations, TLP processing hints, latency tolerance reporting, and optimized buffer flush/fill. Now, let’s look at the demo. 
Here we have the IDT PCI Express switch Gen3 demo. The demo is centered around the recently announced 89H64H16G3 which is the industry’s highest performance PCI Express Gen3 switch. 
The introduction of new technology will often go through a period of collaboration where multiple vendors will evaluate each other’s hardware to validate interoperability across multiple components, equipment, and systems. This is true for this demo. 
We start off with a standard rack server that has a ribbon cable that comes out to connect to the edge connector on the IDT Gen3 switch evaluation platform. The switch evaluation platform has the LeCroy PCI Express Gen3 interposer card inserted into it. The LeCroy PCI Express Gen3 protocol analysis system will be used to show the Gen3 I/O operation.  Inserted into the interposer card is an LSI six-gig SAS HBA. The HBA then connects to a hard disk drive. 
The root complex initiates the PCI Express traffic by accessing a video that is contained on the hard disk drive behind the Gen3 LSI HBA
The PCI Express packets, originating from the root complex, moves through the ribbon cable to the PCI Express switch. The IDT Gen3 switch can then route these packets to its destined port.  In this demo, the board populated is a protocol analyzer interposer card. The PCI Express packets flow through the interposer to the LSI HBA where the PCI Express Gen3 packets are terminated.  If we transition back to the interposer card and move along the protocol analyzer cables, these connect to the LeCroy PCI Express Gen3 Protocol Analyzer. We can see that we have eight lanes operational at a Gen3 data rate of eight gigabit per second. 
This Gen3 operation captured is between the IDT Gen3 switch and the LSI card where the PCI Express packets are destined. 
If we pan over to the monitor, we can see multiple user friendly interfaces being displayed. 
Each of these provide a level of diagnostic capability for the designer. 
There is the LeCroy GUI that indicates the bi eight port at eight gigabit per second operation as well as the detail decoded packet information. 
Also, there is an IDT PCI Express browser tool that provides detailed register configuration and shows the enumeration of the PCI Express switch and the LSI HBA.  In addition, there is an IDT on-die scope tool that leverages both the IDT switch capabilities and the software to provide signal visibility and analyze link integrity. The on-die scope GUI will provide the parameter controls to optimize the receiver and transmitter link characteristics. 
To conclude this demonstration, the introduction of new technologies, or in this case the evolution of technology to a faster speed, can often create challenges during early deployment. Here we’ve seen multiple classes of products and a multi-vendor solution interworking, even during this early stage of deployment. 
The Gen3 PCI Express links are achieving speeds up to eight gigabits per second. However, as mentioned earlier, in addition to the doubling of bandwidth at the physical layer, there are also new protocol extensions that further improve performance and power. 
PCI Express switches are architected and designed with features to better performance and lower power.  Some examples of performance enhancing features include non-blocking crossbar fabric, what are the packet cut-through capabilities, congestion algorithms, port arbitration, multi cast, the size of the port buffering and flow control credits, and more. 
Power saving features may include the ability to power off unused ports and lanes, support for the latest power management specifications, and the ability to fine-tune Certes capabilities. 
In addition to these specific performance and power saving techniques, there is opportunity to provide better performance per watt results for the overall platform with the introduction of new protocol extensions. Here are three PCI Express Gen3 switches that support the new Gen3 protocol extensions. These extensions include atomic operations and TLP processing hints that improve the overall system performance, and latency tolerance reporting and optimized buffer flush/fill that can reduce power consumption by tuning platform power management based on the component characteristics within the system. 
In conclusion, the demo you’ve seen shows Gen3 eight gigabit per second operation using multiple vendors’ products. The protocol extensions we discussed can provide even further opportunities to improve system performance and power.
Should you have any questions about PCI Express or IDT-related products, please contact us at IDT. Thank you for watching.