The 25GbE Datacenter Pipeline


pipeline

SDN may have made networking more exciting thanks to making hardware less important than it has been in the past, but that’s not to say that hardware isn’t important at all. The certainty with which new hardware will come out and make things a little bit faster than before is right there with death and taxes. One of the big announcements yesterday from Hewlett Packard Enterprise (HPE) during HPE Discover was support for a new 25GbE / 100GbE switch architecture built around the FlexFabric 5950 and 12900 products. This may be the tipping point for things.

The Speeds of the Many

I haven’t always been high on 25GbE. Almost two years ago I couldn’t see the point. Things haven’t gotten much different in the last 24 months from a speed perspective. So why the change now? What make this 25GbE offering any different than things from the nascent ideas presented by Arista?

First and foremost, the 25GbE released by HPE this week is based on the Broadcom Tomahawk chipset. When 25GbE was first presented, it was a collection of vendors trying to convince you to upgrade to their slightly faster Ethernet. But in the past two years, most of the merchant offerings on the market have coalesced around using Broadcom as the primary chipset. That means that odds are good your favorite switching platform is running Trident 2 or Trident 2+ under the hood.

With Broadcom backing the silicon, that means wider adoption of the specification. Why would anyone buy 25GbE from Brocade or Dell or HPE if the only vendor supporting it was that vendor of choice? If you can’t ever be certain that you’ll have support for the hardware in three or five years time, making an investment today seems silly. Broadcom’s backing means that eventually everyone will be adopting 25GbE.

Likewise, one of my other impediments to adoption was the lack of server NICs to ramp hosts to 25GbE. Having fast access ports means nothing if the severs can’t take advantage of them. HPE addressed this with the release of FlexFabric networking adapters that can run 25GbE Ethernet. More importantly, those adapters (and switches) can run at 10GbE as well. This means that adoption of higher bandwidth is no longer an all-or-nothing proposition. You don’t have to abandon your existing investment to get to 25GbE right away. You don’t have to build a lab pod to test things and then sneak it into production. You can just buy a 5950 today and clock the ports down to 10GbE while you await the availability and purchasing cycle to buy 25GbE NICs. Then you can flip some switches in the next maintenance window and be running at 25GbE speeds. And you can leave some ports enabled at 10GbE to ensure that there is maximum backwards compatibility.

The Needs of the Few

Odds are good that 25GbE isn’t going to be right for you today. HPE is even telling people that 25GbE only really makes sense in a few deployment scenarios, among which are large container-based hosts running thousands of virtual apps, flash storage arrays that use Ethernet as a backplane, or specialized high-performance computing (HPC) tricks with RDMA and such. That means the odds are good that you won’t need 25GbE first thing tomorrow morning.

However, the need for 25GbE is going to be there. As applications grow more bandwidth hungry and data centers keep shrinking in footprint, the network hardware you do have left needs to work harder and faster to accomplish more with less. If the network really is destined to become a faceless underlay that serves as a utility for applications, it needs to run flat out fast to ensure that developers can’t start blaming their utility company for problems. Multi-core server architectures and flash storage have solved two of the three legs of this problem. 25GbE host connectivity and the 100GbE backbone connectivity tied to it, solve the other side of the equation so everything balances properly.

Don’t look at 25GbE as an immediate panacea for your problems. Instead, put it on a timeline with your other server needs and see what the adoption rate looks like going forward. If server NICs are bought in large quantities, that will drive manufactures to push the technology onto the server boards. If there is enough need for connectivity at these speeds the switch vendors will start larger adoption of Tomahawk chipsets. That cycle will push things forward much faster than the 10GbE / 40GbE marathon that’s been going on for the past six years.


Tom’s Take

I think HPE is taking a big leap with 25GbE. Until the Dell/EMC merger is completed they won’t find themselves in a position to adopt Tomahawk quickly in the Force10 line. That means the need to grab 25GbE server NICs won’t materialize if there’s nothing to connect them. Cisco won’t care either way so long as switches are purchased and all other networking vendors don’t sell servers. So that leaves HPE to either push this forward to fall off the edge of the cliff. Time will tell how this will all work out, but it would be nice to see HPE get a win here and make the network the least of application developer problems.

Disclaimer

I was a guest of Hewlett Packard Enterprise for HPE Discover 2016. They paid for my travel, hotel, and meals during the event. While I was briefed on the solution discussed here and many others, there was no expectation of coverage of the topics discussed. HPE did not ask for, nor were they guaranteed any consideration in the writing of this article. The conclusions and analysis contained herein are mine and mine alone.

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