|By Marten Terpstra||
|October 17, 2013 04:00 PM EDT||
The past few years have seen a dramatic improvement in the latency in network switches. Single ASIC based switches can all pretty much switch packets in less than a microsecond. Current 10GE switching silicon provides anywhere from 300 to 800 nanoseconds, specialized silicon shaves that to less than 200 nanoseconds when limiting the amount of searching that needs to be done by reducing the size of lookup tables. Even other solutions play some smart tricks by providing forwarding hints for intermediate switches make those lookups take less than 50 nanoseconds.
Modular switches inherently have a higher latency. Line cards on modular switches typically have multiple ASICs, those ASICs are connected through a single or multi stage fabric. Each step takes time, resulting in latencies varying from around a microsecond when a packet stays on the same ASIC, to possibly 5-15 microseconds when a packet needs to travel through the fabric and back.
The speediest of ASICs achieve these low numbers by employing cut through switching. Cut through switching allows the ASIC to start transmitting a packet when enough of the header has been received to make a forwarding decision. The ASIC does not wait for the entire packet to be received (the more traditional store-and-forward mechanism), within the first few 100 bytes the forwarding decision has been made, and that same header (modified or not) is being transmitted out the destination port. It's somewhat odd to think that through, but the first bits of a packet may be received by the destination system before the last bits have left the first switch in the network.
Cut through switching comes with quite a few "buts". Most switches can only deploy cut through switching when the source and destination port are the same speed. 10GE in and 40GE out or vice versa is rarely supported and the ASIC will automatically switch to store-and-forward for those packets. For good reason. If a packet comes at you at 40GE rates, you simply cannot transmit it out a 10GE interface, that interface is not fast enough. In the reverse direction speed is not the issue, but if you were to employ cut through switching, for the duration of that packet your 40GE interface effectively runs at 10GE with lots of pauses in between pieces of a packet (figuratively speaking).
In addition, when the destination port has another packet being transmitted or in the queue, a new packet cannot be sent cut through. When another packet is ahead of you, you need to wait. And you may need to wait for quite a while. We often forget that it takes 1.2 microseconds to transmit a 1500 byte packet on a 10GE interface, more than 7 microseconds for a jumbo packet. When the destination port is being paused due to Data Center Bridging Priority Flow Control (PFC), the packet will be queued for store and forward. And make sure you add an extra 3 microseconds for 10GBASE-TX.
Datacenters are on a path to fewer layers of switching. Spine and leaf networks are being pitched as the best performing, low cost solution for dense networks. If you carefully examine the specs and pitches of some of the newer spine switches, you will notice that all of them make a case for deep buffers. Deep buffers assume that this switch needs to manage congestion by buffering packets, why else would you design expensive and power hungry buffer memory into those switches. Buffering and low latency don't go well together. If your spine and leaf network has nothing much to do, you may well see latency numbers of only a few microseconds or better. If the spine layer needs to buffer your packet, this number can jump up quickly to 10s of microseconds. And those large buffers seem to suggest it will.
There certainly are applications that are very sensitive to latency. Financial institution low latency trading networks are the example always used, and there are High Performance Computing environments with database, RDMI or similar applications that benefit from really low latency. Engineering the traffic in such a way that none of the low latency disruptive events described above happen is hard. Really hard. Extremely hard if there is a lot of traffic. Or a lot of endpoints. Networks that are specifically designed to aggregate and distribute (spine and leaf) will be more prone to these latency increasing scenarios. Creating a network with the ability to create isolated direct paths between switches that serve low latency applications is much more likely to avoid these. And even if the absolute latency is not the lowest, consistent latency with little jitter will certainly help the performance of adaptive mechanisms like TCP.
There's a lot of things we do to improve the performance of web and mobile applications. We use caching. We use compression. We offload security (SSL and TLS) to a proxy with greater compute capacity. We apply image optimization and minification to content. We do all that because performance is king. Failure to perform can be, for many businesses, equivalent to an outage with increased abandonment rates and angry customers taking to the Internet to express their extreme displeasure.
Jul. 27, 2016 03:30 PM EDT Reads: 1,572
Right off the bat, Newman advises that we should "think of microservices as a specific approach for SOA in the same way that XP or Scrum are specific approaches for Agile Software development". These analogies are very interesting because my expectation was that microservices is a pattern. So I might infer that microservices is a set of process techniques as opposed to an architectural approach. Yet in the book, Newman clearly includes some elements of concept model and architecture as well as p...
Jul. 27, 2016 02:30 PM EDT Reads: 9,711
No matter how well-built your applications are, countless issues can cause performance problems, putting the platforms they are running on under scrutiny. If you've moved to Node.js to power your applications, you may be at risk of these issues calling your choice into question. How do you identify vulnerabilities and mitigate risk to take the focus off troubleshooting the technology and back where it belongs, on innovation? There is no doubt that Node.js is one of today's leading platforms of ...
Jul. 27, 2016 11:15 AM EDT Reads: 251
SYS-CON Events announced today that LeaseWeb USA, a cloud Infrastructure-as-a-Service (IaaS) provider, will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. LeaseWeb is one of the world's largest hosting brands. The company helps customers define, develop and deploy IT infrastructure tailored to their exact business needs, by combining various kinds cloud solutions.
Jul. 27, 2016 10:30 AM EDT Reads: 1,225
Adding public cloud resources to an existing application can be a daunting process. The tools that you currently use to manage the software and hardware outside the cloud aren’t always the best tools to efficiently grow into the cloud. All of the major configuration management tools have cloud orchestration plugins that can be leveraged, but there are also cloud-native tools that can dramatically improve the efficiency of managing your application lifecycle. In his session at 18th Cloud Expo, ...
Jul. 27, 2016 10:30 AM EDT Reads: 1,080
Ovum, a leading technology analyst firm, has published an in-depth report, Ovum Decision Matrix: Selecting a DevOps Release Management Solution, 2016–17. The report focuses on the automation aspects of DevOps, Release Management and compares solutions from the leading vendors.
Jul. 27, 2016 10:00 AM EDT Reads: 1,743
SYS-CON Events announced today that Venafi, the Immune System for the Internet™ and the leading provider of Next Generation Trust Protection, will exhibit at @DevOpsSummit at 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Venafi is the Immune System for the Internet™ that protects the foundation of all cybersecurity – cryptographic keys and digital certificates – so they can’t be misused by bad guys in attacks...
Jul. 27, 2016 09:15 AM EDT Reads: 1,372
Let's just nip the conflation of these terms in the bud, shall we?
"MIcro" is big these days. Both microservices and microsegmentation are having and will continue to have an impact on data center architecture, but not necessarily for the same reasons. There's a growing trend in which folks - particularly those with a network background - conflate the two and use them to mean the same thing.
They are not.
One is about the application. The other, the network. T...
Jul. 27, 2016 04:30 AM EDT Reads: 3,578
This is a no-hype, pragmatic post about why I think you should consider architecting your next project the way SOA and/or microservices suggest. No matter if it’s a greenfield approach or if you’re in dire need of refactoring. Please note: considering still keeps open the option of not taking that approach. After reading this, you will have a better idea about whether building multiple small components instead of a single, large component makes sense for your project. This post assumes that you...
Jul. 27, 2016 03:45 AM EDT Reads: 4,193
DevOps at Cloud Expo – being held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA – announces that its Call for Papers is open. Born out of proven success in agile development, cloud computing, and process automation, DevOps is a macro trend you cannot afford to miss. From showcase success stories from early adopters and web-scale businesses, DevOps is expanding to organizations of all sizes, including the world's largest enterprises – and delivering real results. Am...
Jul. 27, 2016 02:45 AM EDT Reads: 2,302
The 19th International Cloud Expo has announced that its Call for Papers is open. Cloud Expo, to be held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, brings together Cloud Computing, Big Data, Internet of Things, DevOps, Digital Transformation, Microservices and WebRTC to one location. With cloud computing driving a higher percentage of enterprise IT budgets every year, it becomes increasingly important to plant your flag in this fast-expanding business opportuni...
Jul. 27, 2016 02:15 AM EDT Reads: 2,616
If you are within a stones throw of the DevOps marketplace you have undoubtably noticed the growing trend in Microservices. Whether you have been staying up to date with the latest articles and blogs or you just read the definition for the first time, these 5 Microservices Resources You Need In Your Life will guide you through the ins and outs of Microservices in today’s world.
Jul. 27, 2016 01:15 AM EDT Reads: 4,068
Before becoming a developer, I was in the high school band. I played several brass instruments - including French horn and cornet - as well as keyboards in the jazz stage band. A musician and a nerd, what can I say? I even dabbled in writing music for the band. Okay, mostly I wrote arrangements of pop music, so the band could keep the crowd entertained during Friday night football games. What struck me then was that, to write parts for all the instruments - brass, woodwind, percussion, even k...
Jul. 27, 2016 12:45 AM EDT Reads: 2,244
Internet of @ThingsExpo, taking place November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with the 19th International Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world and ThingsExpo Silicon Valley Call for Papers is now open.
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SYS-CON Events announced today that Isomorphic Software will exhibit at DevOps Summit at 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Isomorphic Software provides the SmartClient HTML5/AJAX platform, the most advanced technology for building rich, cutting-edge enterprise web applications for desktop and mobile. SmartClient combines the productivity and performance of traditional desktop software with the simp...
Jul. 26, 2016 10:45 PM EDT Reads: 1,127
In his session at @DevOpsSummit at 19th Cloud Expo, Yoseph Reuveni, Director of Software Engineering at Jet.com, will discuss Jet.com's journey into containerizing Microsoft-based technologies like C# and F# into Docker. He will talk about lessons learned and challenges faced, the Mono framework tryout and how they deployed everything into Azure cloud. Yoseph Reuveni is a technology leader with unique experience developing and running high throughput (over 1M tps) distributed systems with extre...
Jul. 26, 2016 08:30 PM EDT Reads: 2,156
Jul. 26, 2016 06:45 PM EDT Reads: 3,904
SYS-CON Events has announced today that Roger Strukhoff has been named conference chair of Cloud Expo and @ThingsExpo 2016 Silicon Valley. The 19th Cloud Expo and 6th @ThingsExpo will take place on November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. "The Internet of Things brings trillions of dollars of opportunity to developers and enterprise IT, no matter how you measure it," stated Roger Strukhoff. "More importantly, it leverages the power of devices and the Interne...
Jul. 26, 2016 05:15 AM EDT Reads: 2,156
This digest provides an overview of good resources that are well worth reading. We’ll be updating this page as new content becomes available, so I suggest you bookmark it. Also, expect more digests to come on different topics that make all of our IT-hearts go boom!
Jul. 26, 2016 12:15 AM EDT Reads: 3,669
Keeping pace with advancements in software delivery processes and tooling is taxing even for the most proficient organizations. Point tools, platforms, open source and the increasing adoption of private and public cloud services requires strong engineering rigor – all in the face of developer demands to use the tools of choice. As Agile has settled in as a mainstream practice, now DevOps has emerged as the next wave to improve software delivery speed and output. To make DevOps work, organization...
Jul. 26, 2016 12:00 AM EDT Reads: 2,209