Welcome!

SDN Journal Authors: Elizabeth White, Gil Allouche, Lori MacVittie, Dana Gardner, Adrian Bridgwater

Related Topics: SDN Journal, SOA & WOA, Virtualization, Cloud Expo, Security, Big Data Journal

SDN Journal: Blog Post

Aggregation Is Good. Aggregation Is Bad.

The vast majority of networking equipment is driven by specialized hardware

For as long as I remember networking has struggled with the balance between aggregated and individual traffic flows. Following the abilities of the technology components we use, we have been forced to aggregate, only to be allowed to de-aggregate or skip aggregation when technology caught up or surpassed the needs of today.

The vast majority of networking equipment is driven by specialized hardware. For datacenter switches, speed and port density are driving the requirements and physics and our technology capabilities create trade-offs that ultimately lead to some form of aggregation. Higher speed and more ports are traded off against memory, table space and functionality. These trade-offs will always exist, no matter what we are trying to build. Networking based in servers will have oodles of memory and table space to do very specific things for many many flows, making it extremely flexible, but those same servers cannot touch the packet processing speeds of the specialized packet processing hardware from Broadcom, Intel or Marvell, or the custom ASICs from Cisco, Juniper, or most anyone else.

funnelSo like it or not, we will want to do more than our hardware is capable of and as a result, we create aggregation points in the network where we lump a bunch of flows together into an aggregate flow and start making decisions on those. Nothing new, even good ole IP forwarding is doing so on an aggregate set of flows, it only makes decisions for all flows destined to a specific IP address.

Network tunnels are the most obvious examples of aggregation, their purpose is to hide information from intermediate networking equipment. In some cases we hide it to keep our table sizes under control, in some cases we hide it because we do not want the intermediate equipment to be able to see what we are transporting (IPSec, SSL, etc). And while sometimes the intermediate systems can see everything that is there, managing the complexity of that visibility simply becomes too expensive. This is why networks that are entirely managed and controlled per flow do not really exist at any reasonable scale, and probably never will.

For the exact same reason we aggregate, we lose the ability to act on specifics. When our tables are not large enough to track each and every flow, we can only make decisions based on what we have decided to keep in common. When talking about tunnels, the tunnel endpoints put new headers onto the original packets and intermediate systems can only act (with minor exceptions) on the information provided in these new headers. The original detail is still there and often visible to the intermediate system, but the intermediate system does not have the capacity to act on the sheer volume of that detail.

And there is the struggle. If I have more information, I can make better decisions. But when I aggregate because I cannot handle that extra information (due to sheer size or management complexity), my decisions by definition become more coarse and as a result, less accurate. But we want it all. We want the power to make decisions based on the most specific information we can, but want to aggregate for operational simplicity or because our hardware dictates. And this is where we get creative and start to turn what used to be black and white into gray.

There is nothing wrong with attempting to act on specifics for aggregate flows, but in so many cases its done as an afterthought and becomes hard to manage, control or specify. Some of the techniques we use are fairly clean, like taking the DSCP values from a packet and replicating it in the outer header of that same packet in a tunnel. Others are far more obscure like calculating some hash function on a packet header and using it as the UDP source port for the VXLAN encapsulated version of that packet. In even others, the original internals may be completely invisible to intermediate systems. STT for instance re-uses the format of TCP packets for its own purpose, but as a side effect of using it as a streaming-like protocol is that the original packet headers may not actually be in an IP packet on the wire. The STT header provides for a 64 bit Context-ID that can be used to take some bits of information from the original packet, but that STT header only appears in the first of what could be many individual packets that are re-assembled in the receiving NIC. Over the Christmas break I spent some time looking at each of the overlay formats and the tools modern day packet processors give you to act on these headers. I will share some of this in this forum next week.

Ultimately, overlay networks are creating a renewed emphasis on the choices between aggregation and individuality. Designed specifically to allow for more complex and scaled networks that hide a lot of the details from the dedicated network hardware, it comes with the price of less granular decisions by that hardware, which can certainly lead to less than optimal use of the available network.

[Today's fun fact: In the Netherlands, there is a 40% higher chance of homeowner insurance claims on the home owner's birthday. Those are some good parties.]

The post Aggregation is Good. Aggregation is Bad. appeared first on Plexxi.

Read the original blog entry...

More Stories By Marten Terpstra

Marten Terpstra is a Product Management Director at Plexxi Inc. Marten has extensive knowledge of the architecture, design, deployment and management of enterprise and carrier networks.

@CloudExpo Stories
High-performing enterprise Software Quality Assurance (SQA) teams validate systems that are ready for use - getting most actively involved as components integrate and form complete systems. These teams catch and report on defects, making sure the customer gets the best software possible. SQA teams have leveraged automation and virtualization to execute more thorough testing in less time - bringing Dev and Ops together, ensuring production readiness. Does the emergence of DevOps mean the end of E...
Scott Jenson leads a project called The Physical Web within the Chrome team at Google. Project members are working to take the scalability and openness of the web and use it to talk to the exponentially exploding range of smart devices. Nearly every company today working on the IoT comes up with the same basic solution: use my server and you'll be fine. But if we really believe there will be trillions of these devices, that just can't scale. We need a system that is open a scalable and by using ...
The Internet of Things is tied together with a thin strand that is known as time. Coincidentally, at the core of nearly all data analytics is a timestamp. When working with time series data there are a few core principles that everyone should consider, especially across datasets where time is the common boundary. In his session at Internet of @ThingsExpo, Jim Scott, Director of Enterprise Strategy & Architecture at MapR Technologies, discussed single-value, geo-spatial, and log time series dat...
"Verizon offers public cloud, virtual private cloud as well as private cloud on-premises - many different alternatives. Verizon's deep knowledge in applications and the fact that we are responsible for applications that make call outs to other systems. Those systems and those resources may not be in Verizon Cloud, we understand at the end of the day it's going to be federated," explained Anne Plese, Senior Consultant, Cloud Product Marketing at Verizon Enterprise, in this SYS-CON.tv interview at...
"For the past 4 years we have been working mainly to export. For the last 3 or 4 years the main market was Russia. In the past year we have been working to expand our footprint in Europe and the United States," explained Andris Gailitis, CEO of DEAC, in this SYS-CON.tv interview at Cloud Expo, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
P2P RTC will impact the landscape of communications, shifting from traditional telephony style communications models to OTT (Over-The-Top) cloud assisted & PaaS (Platform as a Service) communication services. The P2P shift will impact many areas of our lives, from mobile communication, human interactive web services, RTC and telephony infrastructure, user federation, security and privacy implications, business costs, and scalability. In his session at @ThingsExpo, Robin Raymond, Chief Architect...
The Domain Name Service (DNS) is one of the most important components in networking infrastructure, enabling users and services to access applications by translating URLs (names) into IP addresses (numbers). Because every icon and URL and all embedded content on a website requires a DNS lookup loading complex sites necessitates hundreds of DNS queries. In addition, as more internet-enabled ‘Things' get connected, people will rely on DNS to name and find their fridges, toasters and toilets. Acco...
The term culture has had a polarizing effect among DevOps supporters. Some propose that culture change is critical for success with DevOps, but are remiss to define culture. Some talk about a DevOps culture but then reference activities that could lead to culture change and there are those that talk about culture change as a set of behaviors that need to be adopted by those in IT. There is no question that businesses successful in adopting a DevOps mindset have seen departmental culture change, ...
"Cloud consumption is something we envision at Solgenia. That is trying to let the cloud spread to the user as a consumption, as utility computing. We want to allow the people to just pay for what they use, not a subscription model," explained Ermanno Bonifazi, CEO & Founder of Solgenia, in this SYS-CON.tv interview at Cloud Expo, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
Enthusiasm for the Internet of Things has reached an all-time high. In 2013 alone, venture capitalists spent more than $1 billion dollars investing in the IoT space. With "smart" appliances and devices, IoT covers wearable smart devices, cloud services to hardware companies. Nest, a Google company, detects temperatures inside homes and automatically adjusts it by tracking its user's habit. These technologies are quickly developing and with it come challenges such as bridging infrastructure gaps,...
SYS-CON Media announced that Centrify, a provider of unified identity management across cloud, mobile and data center environments that delivers single sign-on (SSO) for users and a simplified identity infrastructure for IT, has launched an ad campaign on Cloud Computing Journal. The ads focus on security: how an organization can successfully control privilege for all of the organization’s identities to mitigate identity-related risk without slowing down the business, and how Centrify provides ...
SAP is delivering break-through innovation combined with fantastic user experience powered by the market-leading in-memory technology, SAP HANA. In his General Session at 15th Cloud Expo, Thorsten Leiduck, VP ISVs & Digital Commerce, SAP, discussed how SAP and partners provide cloud and hybrid cloud solutions as well as real-time Big Data offerings that help companies of all sizes and industries run better. SAP launched an application challenge to award the most innovative SAP HANA and SAP HANA...
"SAP had made a big transition into the cloud as we believe it has significant value for our customers, drives innovation and is easy to consume. When you look at the SAP portfolio, SAP HANA is the underlying platform and it powers all of our platforms and all of our analytics," explained Thorsten Leiduck, VP ISVs & Digital Commerce at SAP, in this SYS-CON.tv interview at 15th Cloud Expo, held Nov 4-6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
"We help companies that are using a lot of Software as a Service. We help companies manage and gain visibility into what people are using inside the company and decide to secure them or use standards to lock down or to embrace the adoption of SaaS inside the company," explained Scott Kriz, Co-founder and CEO of Bitium, in this SYS-CON.tv interview at 15th Cloud Expo, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
Explosive growth in connected devices. Enormous amounts of data for collection and analysis. Critical use of data for split-second decision making and actionable information. All three are factors in making the Internet of Things a reality. Yet, any one factor would have an IT organization pondering its infrastructure strategy. How should your organization enhance its IT framework to enable an Internet of Things implementation? In his session at Internet of @ThingsExpo, James Kirkland, Chief Ar...
SAP is delivering break-through innovation combined with fantastic user experience powered by the market-leading in-memory technology, SAP HANA. In his General Session at 15th Cloud Expo, Thorsten Leiduck, VP ISVs & Digital Commerce, SAP, discussed how SAP and partners provide cloud and hybrid cloud solutions as well as real-time Big Data offerings that help companies of all sizes and industries run better. SAP launched an application challenge to award the most innovative SAP HANA and SAP HANA...
Bit6 today issued a challenge to the technology community implementing Web Real Time Communication (WebRTC). To leap beyond WebRTC’s significant limitations and fully leverage its underlying value to accelerate innovation, application developers need to consider the entire communications ecosystem.
The definition of IoT is not new, in fact it’s been around for over a decade. What has changed is the public's awareness that the technology we use on a daily basis has caught up on the vision of an always on, always connected world. If you look into the details of what comprises the IoT, you’ll see that it includes everything from cloud computing, Big Data analytics, “Things,” Web communication, applications, network, storage, etc. It is essentially including everything connected online from ha...
Cloud Expo 2014 TV commercials will feature @ThingsExpo, which was launched in June, 2014 at New York City's Javits Center as the largest 'Internet of Things' event in the world.
SYS-CON Events announced today that Windstream, a leading provider of advanced network and cloud communications, has been named “Silver Sponsor” of SYS-CON's 16th International Cloud Expo®, which will take place on June 9–11, 2015, at the Javits Center in New York, NY. Windstream (Nasdaq: WIN), a FORTUNE 500 and S&P 500 company, is a leading provider of advanced network communications, including cloud computing and managed services, to businesses nationwide. The company also offers broadband, p...