Network Break 15
The Network Break returns with Show 15.
Author information
The post Network Break 15 appeared first on Packet Pushers Podcast and was written by Greg Ferro.
Windows ISATAP Client, Part 2
In Part 1 we discussed how to turn off ISATAP on Windows host—which is a great idea. Turning off unnecessary components of your network simplifies everything. But ISATAP can be useful in certain scenarios. For instance, if you want to test an application on IPv6 you clearly don’t want to turn on IPv6 everywhere and […]
Author information
The post Windows ISATAP Client, Part 2 appeared first on Packet Pushers Podcast and was written by Dan Massameno.
Musing: First thoughts on how Cisco ACI Works
I've been reading the Cisco Application Centric Infrastructure Design Guide. Sometimes I see a product of genius and wondrous use of technology, other times I'm like 'did they do it the hard way or what' ?
The post Musing: First thoughts on how Cisco ACI Works appeared first on EtherealMind.
The Impact of Data Gravity: a Campfire Story
Here’s an interesting story illustrating the potential pitfalls of multi-DC deployments and the impact of data gravity on application performance.
Long long time ago on a cloudy planet far far away, a multinational organization decided to centralize their IT operations and move all workloads into a central private cloud.
Read more ...802.11ac Receiver Sensitivity
Following my previous post regarding typical SNR to MCS rate mappings for Wi-Fi clients, an interesting discussion was held on Twitter regarding the effects of increased channel width on the ability of a client to decode frames at any given SNR. Long story short, wider channels increase the noise power captured by the receiving radio which reduces its SNR. For every doubling of channel width, you require 3dB better signal to achieve the same MCS rate.George Ou created a chart showing the relative range of each MCS rate based at various channel widths:
@revolutionwifi @vall_wifi @KeithRParsons The negative effects on effective range with wider channels http://t.co/wyg3qtQjJl
— George Ou (@GeorgeOu) August 20, 2014
Following up on his work, I thought it would be useful to provide some context around these coverage ranges by referencing it against a typical noise floor of -93 dBm found in many environments. Using this noise floor and the SNR to MCS rate mapping table, combined with the relative coverage ranges (based on RF signal propagation using the inverse square law) we can visualize what data rates a typical 802.11ac radio will experience at various RSSI and SNR signal levels for each channel Continue reading
VRF based path selection
In this post I will be showing you how its possible to use different paths between your PE routers on a per VRF basis.
This is very useful if you have customers you want to “steer” away from your normal traffic flow between PE routers.
For example, this could be due to certain SLA’s.
I will be using the following topology to demonstrate how this can be done:
A short walkthrough of the topology is in order.
In the service provider core we have 4 routers. R3, XRv-1, XRv-2 and R4. R3 and R4 are IOS-XE based routers and XRv-1 and XRv-2 are as the name implies, IOS-XR routers. There is no significance attached to the fact that im running two XR routers. Its simply how I could build the required topology.
The service provider is running OSPF as the IGP, with R3 and R4 being the PE routers for an MPLS L3 VPN service. On top of that, LDP is being used to build the required LSP’s. The IGP has been modified to prefer the northbound path (R3 -> XRv-1 -> R4) by increasing the cost of the R3, XRv-2 and R4 to 100.
So by default, traffic between Continue reading
Pmacct: the Traffic Analysis Tool with Unpronounceable Name
SDN evangelists talking about centralized traffic engineering, flow steering or bandwidth calendaring sometimes tend to gloss over the first rule of successful traffic engineering: Know Thy Traffic.
In a world ruled by OpenFlow you’d expect the OpenFlow controller to know all the traffic; in more traditional networks we use technologies like NetFlow, sFlow or IPFIX to report the traffic statistics – but regardless of the underlying mechanism, you need a tool that will collect the statistics, aggregate them in a way that makes them usable to the network operators, report them, and potentially act on the deviations.
Read more ...Visualizing How Wi-Fi SNR Helps Determine the Achievable MCS Data Rate
If a Wi-Fi station has a better signal, you get more throughput. Everyone knows that. Here is a handy chart to help visualize it.This table shows the "typical" data rates that Wi-Fi stations can achieve based on their SNR (signal to noise ratio). I say "typical" because it actually varies based on the radio chipset receiver sensitivity, but these values are a good starting point for most devices.
The achievable data rate (MCS rate) varies based on a number of variables:
- The 802.11 protocol - really a function of the increasing maturity of chipsets over time to handle more complex modulation types even when SNR is a bit lower.
- The channel width - typically doubling the channel width increases the noise floor by 3 dB, which decreases SNR. So to get the same MCS rate on wider channels you need higher SNR.
- The complexity of the modulation - notice as you get into more complex modulations like 64-QAM and 256-QAM that it doesn't take much more SNR to move from the lower encoding rate to the higher encoding rate, and vice versa in the opposite direction.
 |
| Typical Wi-Fi SNR to MCS Data Rate Mappings (Download for full resolution Continue reading |
Building a router with Open vSwitch
As part of my work in OpenDaylight, we are looking at creating a router using Open vSwitch... Why? Well OpenStack requires some limited L3 capabilities and we think that we can handle those in a distributed router.
Test Topology
My test topology looks like this:
We have a host in an external network 172.16.1.0/24, one host in an internal network 10.10.10.0/24 and two hosts in another internal network 10.10.20.0/24.
As such, The hosts in the 10.x.x.x range should be able to speak to each other, but should not be able to speak to external hosts.
The host 10.10.10.2 has a floating IP of 172.16.1.10 and should be reachable on this address from the external 172.16.1.0/24 network. To do this, we'll use DNAT for traffic from 172.16.1.2 -> 172.16.1.10 and SNAT for traffic back from 10.10.10.2 -> 172.16.1.2
If you'd like to recreate this topology you can checkout the OpenDaylight OVSDB project source on GitHub and:
vagrant up mininet
vagrant ssh mininet
cd /vagrant/resources/mininet
sudo mn --custom Continue readingBuilding a router with Open vSwitch
As part of my work in OpenDaylight, we are looking at creating a router using Open vSwitch... Why? Well OpenStack requires some limited L3 capabilities and we think that we can handle those in a distributed router.
Bare Metal Networking, Then and Now…
What a difference a year makes.
Just last year, bare metal networking was viewed as an aspiration for only mega-scale operators. A simple solution to enable any bare metal switch to operate any networking operating system was unavailable.
Original design manufacturers (ODMs) and bare metal networking vendors were relatively unknown entities. Pricing and product availability was obscure or difficult to ascertain. The supply chain for bare metal networking was non-existent. (You can read more about The Modern Networking Supply Chain and the Death of the Multiplier Effect.) Consequently, mega-scale operators deployed solutions, procured directly from ODMs in lots of hundreds to thousands.
Today, bare metal networking is available to the mass market around the world.
The Open Network Install Environment, ONIE, is a fundamental enabler to bare metal networking. ONIE is an Open Compute Project (OCP, pioneered by Facebook) initiative facilitating any network operating system to be installed (or removed) on any ONIE-based switch. Bare metal networking vendors have adopted ONIE en masse, simplifying operations for distributors and resellers with a minimum number of hardware SKUs, in parallel, making the simplified supply chain available to a range of software suppliers. Today, there are approximately 20 ONIE-based platforms in flexible Continue reading
Multicast Rising
by Steve Harriman, VP of Marketing - August 19, 2014
Multicast hasn’t been a hot topic in networking in recent years, but that may be changing with last week’s announcements by both AT&T and Verizon that they will launch LTE multicast in 2015. Verizon plans to start embedding the technology in phones in the fourth quarter of this year and commercially launch the service in 2015. AT&T will also begin to roll out multicast capabilities next year.
According to Verizon CFO Fran Shammo, multicast is “…the pivotal point that starts to change the way content is delivered over a mobile handset which opens up content into the wireless world."
As Humberto Saabedra explains in an article for PhoneNews.com: “LTE Multicast allows the same content to be sent to a large number of subscribers at the same time, resulting in a more efficient use of network resources than each user requesting the same content and then having the content individually streamed to each user.”
Currently, organizations use multicast for multimedia distribution, desktop imaging, market trading data distribution, broadcast video, online education, and other purposes where data must be delivered simultaneously to multiple receivers. Packet Continue reading
Do We Need To Redefine Open?
There’s a new term floating around that seems to be confusing people left and right. It’s something that’s been used to describe a methodology as well as used in marketing left and right. People are using it and don’t even really know what it means. And this is the first time that’s happened. Let’s look at the word “open” and why it has become so confusing.
Talking Beer
For those at home that are familiar with Linux, “open” wasn’t the first term to come to mind. “Free” is another word that has been used in the past with a multitude of loaded meanings. The original idea around “free” in relation to the Open Source movement is that the software is freely available. There are no restrictions on use and the source is always available. The source code for the Linux kernel can be searched and viewed at any time.
Free describes the fact that the Linux kernel is available for no cost. That’s great for people that want to try it out. It’s not so great for companies that want to try and build a business around it, yet Red Hat has managed to do just that. How can they Continue reading
A History of Load Balancing
A visual representation of the company and, to a lesser extent, product history of the load balancing/application delivery field. My usual F5 bias is present but it seems justified considering their long-held market leading position. I’ve been itching to post this for a while but simply couldn’t stop changing the formatting. I can’t say I’m […]
Author information
The post A History of Load Balancing appeared first on Packet Pushers Podcast and was written by Steven Iveson.
DIY Web Server: Raspberry Pi + CloudFlare
The Raspberry Pi was created with a simple mission in mind: change the way people interact with computers. This inexpensive, credit card-sized machine is encouraging people, especially kids, to start playing with computers, not on them.
When the first computers came out, basic programming skills were necessary. This was the age of the Amigas, BBC Micros, the Spectrum ZX, and Commodore 64s. The generation that grew up with these machines gained a fundamental understanding how how computers work.
Computers today are easy to use and require zero understanding of programming to operate. They’re also expensive, and wrapped in sleek cases. While aesthetically pleasing designs and user friendly interfaces make computers appealing and accessible to everyone, these advances create a barrier to understanding how computers work and what they are capable of doing. This isn’t necessarily a problem, but for those who really understand computers, it seems that our collective sense of the power of computing has been dulled.
Raspberry Pi marks the beginning of a conscious effort to return to computing fundamentals. Starting at about $25—case not included—it’s purposely designed to remove barriers to tinkering, reprograming, and, ultimately, to understanding how computers work. This return to fundamentals is rejuvenating the Continue reading
Revisited: Layer-2 DCI over VXLAN
I’m still getting questions about layer-2 data center interconnect; it seems this particular bad idea isn’t going away any time soon. In the face of that sad reality, let’s revisit what I wrote about layer-2 DCI over VXLAN.
VXLAN hasn’t changed much since the time I explained why it’s not the right technology for long-distance VLANs.
Read more ...CloudFlare hiring Go programmers in London and San Francisco
Are you familiar with the Go programming language and looking for a job in San Francisco or London? Then think about applying to CloudFlare. We're looking for people with experience writing Go in both locations.
CC BY-SA 2.0 by Yuko Honda (cropped, resized)
CloudFlare uses Go extensively to build our service and we need to people to build and maintain those systems. We've written a complete DNS server in Go, our Railgun service is all Go and we're moving more and more systems to Go programs.
We've recently written about our open source Red October Go project for securing secrets, and open-sourced our CFSSL Go-based PKI package. Go is now making its way into our data pipeline and be used for processing huge amounts of data.
We even have a Go-specific section on our GitHub.
If you're interested in working in Go on a high-performance global network like CloudFlare, send us an email.
Not into Go? We're hiring for all sorts of other positions and technologies.
Building a router with Open vSwitch
As part of my work in OpenDaylight, we are looking at creating a router using Open vSwitch... Why? Well OpenStack requires some limited L3 capabilities and we think that we can handle those in a distributed router.
Blame the System For Resisting Change – Not The People
I often hear vendors and pundits proclaim that Enterprise is resisting change. In particular, they say that individuals in Enterprises can't see the change or won't discuss buying new technology. I see these objections as failure of the current system and much less due to the people.
The post Blame the System For Resisting Change – Not The People appeared first on EtherealMind.