There were a lot of cool things at InterOp, but not much that was new from the big vendors. I was hoping for some big announcements or new toys but … nothing. For example, Cisco didn’t announce anything, probably waiting announce at Cisco Live in July where they can control the press and message much more tightly. However, HP announced the A10500 switch (action pictures ) which is a new campus switch and Gnodal arrived with new products (more on this later).
However in the centre of the HP stand there was something very cool – a prototype E8212 ProCurve switch with a fully optical backplane.
The line cards project out of the unit because the prototype optoelectronics boards haven’t yet been commoditised into chips. That’s normal for these prototype projects. The next image shows a slightly different angle and I’ve marked up the pieces.
But what does the backplane look like – I took a photo of that too. See that black vertical line there ?
And this is a photo showing the photo of the actual optical backplane assembly (I like the wooden ruler they used to show how big it is).
This element is a very low cost, Optical Backplane based on a passive optical multi-bus system architecture
- 12 channel, 1:6 broadcast for 120Gbps per tap
- Very low cost injection molding fabrication
- Low cost MEMs non-polarizing beam splitters
- Commercially available VCSEL based OE engines
- Passive backplane that scales to terabits per tap using faster optoelectronics and CWDM
Backplanes – Active, Passive, Optical
The role of backplanes in chassis based switches is vital to their success. Most chassis switches used in networking 1 use a passive backplane. This is usually some type of complex and hard to manufacture PCB board with electrical traces on it, and a bunch of mechanical connectors. Passive backplanes are usually cheaper, and much more reliable than active backplanes. Modules simply connect to the backplane and all electronics is contained on the line cards. You can think of a passive backplane as a bunch of high performance cables.
It’s my understanding that the Catalyst 4500 is an passive backplane (although, the latest version 4500-R possibly is not).
Active backplanes are used when highest performance is required at a point in time. The electrical signal transmitted over the backplane degrades in performance at higher clock speeds. By adding electronics and chips to the backplane, better performance can be achieved be managing the signal and clocking more effectively. However, this is at the cost of lower reliability and atrocious MTTR for failure. That is, the backplane is normally fixed in the chassis casing, and a failure of the backplane components means replacing the entire chassis. Because switch chassis are almost impossible to replace, and take tens to hundreds of hours of downtime, active backplanes are a cause of concern. They also cost more to manufacture.
Examples of active backplanes are the C6500 and Nexus 7000. I’m not sure about other vendors as there is very little documentation, customers don’t ask these days so vendors aren’t talking about it.
This images show the traces that have been laid down on the plastic substrate for the prototype backplane – I find this fascinating.
The advantage of optical backplanes is at several, rather separate levels:
|High Performance||Bandwidth can scale according to optical line driver performance and less limitations due to poor signal integrity because of electrical propagation|
|Scalability, investment protection||Optical backplane is passive, so performance of the chassis can be upgraded by adding CWDM capable modules|
|Low Power consumption||Energy efficiency and low thermal generation|
|High Volume manufacturing||Manufacturing a suitable plastic is far less complex than precision PCB layout|
|Backplane performance independence||Data transfer performance can scale according to CWDM drivers on the processor and switch line cards. Thus replacing line cards can continue to upgrade the switch performance for a longer time.|
Multi-Bus not Crossbar
In this case, HP has implemented a multi-bus system architecture without a central crossbar fabric. This means that each line card performs the forwarding decision for the outbound destination. Although crossbar fabrics have been popular for a number of years, designs can return to distributed forwarding because there would be suffcient bandwidth in the backplane.
This means that
- the up-front cost of the chassis is reduced because you don’t need the expensive and power hungry crossbar silicon fabric for the first line card. Chassis cost scales linearly as modules are added.
- performance scales with each additional line card since they add “bandwidth” by having local forwarding across the backplane. Better planning and more predictable outcomes.
- that there are less critical dependencies in the switch chassis for mechanical and electrical failure.
- the management module acts to manage, not supervise and becomes lower cost.
- optical backplanes are cheap to produce, and cheaper to maintain. Lower maintenance costs.
The EtherealMind View
There are several points of interest here.
- these products are three to five years away according to Charles Clarke, Research Director of HP. It’s just manufacturing and marketing from here
- these products are expected to be cheaper than current switches, a lot cheaper for more performance.
- They will have significant levels of future proofing by allowing for up to 2Tbps per channel (compared to 120Gbps today)
- they will be used in smaller devices at first, mainly access or aggregation switches.
It’s the first time I’ve seen HP start talking about future products without an NDA. Normally, HP says nothing about futures, and when they do, it’s involves lawyers and stringent controls. Here’s hoping to more openness that lets me plan my strategy more effectively. Does this presage a now HP who is willing to engage with customers ?
HP has demonstrated some serious research work in networking. I’m impressed. It’s a shame they are using the ProCurve software/hardware platform which has a poor reputation in industry around software reliability, so here’s hoping they decide to use this technology in the A-series switch running ComWare.
HP Networking have paid for my travel and accommodation for Interop so that I was able to attend their briefings, meet executives and have good quality discussions. I’d like to think that my opinions and views are my own. It’s great to get access to information and the chance to learn new things. I am not remunerated in any other way. I didn’t even take the tchotckes.
- backplanes are used in many electronic applications, including servers, aeropsace, control systems as more. There isn’t anything that’s unique about networking electronics except the higher speeds / performance. ↩