Howard Marks from Deep Storage and long-term curmudgeon sent Ethan & I the following email: As I continue to tilt at the VMware windmill I’m facing fanbois telling me that all you have to do is plug the EVO:RAIL in and turn it on. This of course leaves out the fact that the little sucker still […]
The post Unreliable Multicast means Unreliable VMware VSAN appeared first on EtherealMind.
I’m sure that we have all experienced poorly designed Wi-Fi networks. When a technology is so ubiquitous, so easily accessible, and is increasingly the most relied upon method of Internet access for mobile devices and cloud computing, then there are bound to be some issues. Unfortunately, the prevalence of underperforming Wi-Fi networks is still much too common for my liking.
Great Wi-Fi starts with proper design. There are various approaches to WLAN design that have evolved over time, ranging from providing basic coverage to maximum capacity and situations in-between.
At one end of the spectrum, we have a basic coverage oriented design. This was the historical way of designing a WLAN that simply involved ensuring adequate signal strength from access points was present in desired locations. At the other end of the spectrum is a design focusing on maximum capacity. This involves careful RF planning in order to integrate the most Wi-Fi cells as possible into a physical area.
The problem with both of these approaches is that they are the extremes and aren't applicable for many wireless networks. Basic coverage designs may still work for warehouses and some retailers and maximum capacity designs are great for stadiums and Continue reading
The edited videos for Scaling Overlay Virtual Networking webinar are available on ipSpace.net Content site. Nuage Networks sponsored the webinar; the videos are thus publicly available (without registration).
The Network Access Broker Conceptual Demo
Talk is cheap when it comes to SDN, but at Packet Design we’ve created a working SDN analytics and orchestration prototype that will enable network engineers to effectively manage hybrid networks. In this new demo, we outline how our Network Access Broker (NAB) – based on our core Route Explorer™ System – analyzes application requests for network resources, assesses their impact on services, and provisions them optimally using a combination of the following (if you’re already familiar with SDN and its management challenges, you can skip the intro and head straight to the demo at the 2:47 mark):
In the NAB demo, we use Continue reading
#10: The CIA coordinated the release of classified information to the media, including inaccurate information concerning the effectiveness of the CIA's enhanced interrogation techniques. The CIA's Office of Public Affairs and senior CIA officials coordinated to share classified information on the CIA's Detention and Interrogation Program to select members of the media to counter public criticism, shape public opinionOf course they did, but then so did the Senate committee itself. They've been selectively leaking bits of the report for over a year. Their description of the "CIA hacking" scandal was completely inaccurate.
Recently, I’ve heard several people suggest that the advent of IPv6 changes the requirements for data-center virtual network solutions. For instance, making the claim that network overlays are no longer necessary. The assumption made is that once an instance has a globally unique IP address that all requirements are met.
In my view, this analysis fails in two dimensions:
Neither of these assumptions hold when examined in detail.
While there are IaaS use cases of users that just want to be able to fire up a single virtual-machine and use it as a personal server, the most interesting use case for IaaS or PaaS platforms is to deploy applications.
These applications, serve content for a specific virtual IP address registered in the DNS and/or global load-balancers; that doesn’t mean that this virtual IP should be associated with any specific instance. There is layer of load-balancing that maps the virtual IP into the specific instance(s) service the content. Typically this is done with a load-balancer in proxy mode.
As an aside, enabling IPv6 in the load-balancer Continue reading
steal (since Linux 2.6.11)Keeping close track of the stolen time metric is particularly import when running managing virtual machines in a public cloud. For example, Netflix and Stolen Time includes the discussion:
(8) Stolen time, which is the time spent in other operating systems
when running in a virtualized environment
So how does Netflix handle this problem when using Amazon’s Cloud? Adrian admits that they tracked this statistic so closely that when an instance crossed a stolen time threshold the standard operating procedure at Netflix was to kill the VM and start it up on a different hypervisor. What Netflix realized over time was that once a VM was performing poorly because another VM was crashing the party, usually due to a poorly written or compute intensive application hogging the machine, it never really got any better and their best learned approach was to get off that machine.The following articles describe how to monitor public cloud instances using Host sFlow agents:
Christmas is lurking around the corner and in the spirit of Denise “Fish” Fishburne, I give you the “The Tale of the Mysterious PIM Prune”.
I have been working a lot with multicast lately which is also why I’ve blogged about it. To start off this story, let’s begin with a network topology.
The multicast source is located in AS 65000 and contains two routers that are connected to the multicast source. The routers run BFD, OSPF, iBGP, PIM internally and the RP is located on C1. There is a local receiver in AS 65000 and a remote one in AS 64512. The networks 10.0.1.0/24 and 10.0.21.0/24 come off the same physical interface. If you want to replicate this lab, all the configs are provided here.
This network requires fast convergence and I have been troubleshooting a scenario where the active multicast router (R1) has its LAN interface go down, meaning that the traffic from the source must come in on R2. In this scenario I have seen convergence in up to 60 seconds which is not acceptable. The BGP design is for R2 to still exit out via R1 if the link is Continue reading
It’s time for the Network Break! Sit back, grab a coffee, and join us for an analysis of the latest IT news, vendor moves and new product announcements. We’ll separate the signal from the noise--or at least make some noise of our own.
The post Network Break 24 appeared first on Packet Pushers Podcast and was written by Greg Ferro.
No. When compared to the operation of existing networks, SDN is much more secure.
The post Are SDN Controllers a Security Risk ? appeared first on EtherealMind.
Powerpoint doesn’t stink. Our presentation skills do. So how do we fix it?
First, you must decide: what do I want this presentation to be? We’ve all seen the brilliant TED talks about new ideas. We’ve all seen the really cool sample presentations from those online presentation sites about someone’s trip around the world. When you’re looking at those talks, though, remember this: they are selected out of millions of talks for their content, and their content fits their format. I’ve seen folks do fairly standard slideshows with Prezy. It doesn’t work. I’ve also seen people do “let me tell you about my trip” presentations with Powerpoint. Again, it doesn’t work.
So, just like network engineering, pick the right tool for the job. Since most of an engineer’s presentations aren’t going to feature exciting trips down the River of Doubt, or even up Doubtin’ Mountain, we’re probably pretty safe to stick with a fairly standard presentation package — slides, warts, and all.
Yes, it’s important to get the flow right. I once stood in for a presenter who’d lost his voice — the material was router architecture (hardware and software), so it’s a topic I know well, so I wasn’t Continue reading
