The Tale of the Mysterious PIM Prune
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
Network Break 24
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.
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The post Network Break 24 appeared first on Packet Pushers Podcast and was written by Greg Ferro.
Are SDN Controllers a Security Risk ?
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.
When and when not to multithread
At the end of my last post on Python multithreading, I said my example was not the best. Let me expand some more on this. While testing code in the previous post, I noticed that certain code was slower when multiple threads were running. Also these threads are not tied to a CPU. If we […]HP Unified Wireless: Portal free user-url
On the Unified wireless solution, guest users can be authenticated through the captive web-portal feature of the portal server. The network admin could allow some guest traffic to pass without guest authentication to provide a “walled-garden” solution. This was already … Continue reading
Why Your Presentation Stinks (Part 1)
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
Dial-Peer Digit Manipulation
In the CCIE Collaboration lab, understanding dial-peers is extremely important. Lack of knowledge in this area can yield devastating results in your lab score report since they can be found in so many different sections of the exam. We must be thoroughly prepared to tackle every aspect of this technology should we be presented with it at some point.
I recently got a great question in our forums about digit manipulation within POTS dial-peers and how they interact with translation rules and profiles. I figured that since this is such an important topic, my answer to his question bears repeating so it can reach a wider audience.
Let’s begin with the simple example of dialing the number “123” from a CUCME phone. Of course, the POTS dial-peer must be created to support the desired behavior.
When this pattern is selected, all digits will be stripped automatically since they are explicitly defined. This is due to the “automatic POTS dial-peer digit strip” feature in IOS. See below for the ISDN Q.931 debug output (no Called Party Number).
Since we are not currently sending a Called Party Number, we’ll need some way to add the digits back to the string to Continue reading
Enterprises Have Many Unprofitable Applications, Public Clouds Do Not
Enterprise IT supports many unprofitable applications. Microsoft Exchange, legacy databases, obsolete accounting systems, end-of-life desktop operating systems and much more. Public clouds can, and do, cancel unprofitable products. This is a brutal truth in cloud planning. Takeaways: Enterprise IT supports many applications that are unprofitable to own and maintain Executives and managers are commonly unprepared […]
The post Enterprises Have Many Unprofitable Applications, Public Clouds Do Not appeared first on EtherealMind.
BGPSEC: Protections Offered
In my last post on the subject of BGPSEC, I explained the basic operation of the modifications to BGP itself. In this post, I’ll begin looking at some of the properties — both good and bad — of these extensions to BGP. To being, we’ll look at the simple network illustrated here, and see what […]
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The post BGPSEC: Protections Offered appeared first on Packet Pushers Podcast and was written by Russ White.
Webinars in 2014, and a Quick Peek Into 2015
I promise engineers who renew their subscription 4-6 new webinars a year. It’s time to see whether I kept that promise in 2014.
TL&DR summary: it was a great year, but I still missed a few things.
Read more ...Sorting Bookmarks in Safari for Mac OS X
If you’re anything like me, then you may just be a bit OCD or ANAL when it comes to some things. One of those things is, I like my bookmarks/favorites in alphabetical order with folders sorted...[[ Summary content only, you can read everything now, just visit the site for full story ]]
Cisco CSR1000v on Qemu
http://brezular.com/2013/08/18/cisco-csr-1000v-installation-on-qemu-virtual-machine/ Added part - License Activation for Cisco IOSOpendaylight Helium release
Earlier, I was using Opendaylight Hydrogen release and recently, I tried out Opendaylight Helium release. In this blog, I have shared some of my experiences with Helium. Following are some important additions to Helium compared to Hydrogen. For more details, please refer Opendaylight webpage. Hardening of the controller, Clustering capability, Security options like AAA. Better … Continue reading Opendaylight Helium release
Sorting Bookmarks in Safari for Mac OS X
If you’re anything like me, then you may just be a bit OCD or ANAL when it comes to some things. One of those things isI like my bookmarks/favorites in alphabetical...[[ Summary content only, you can read everything now, just visit the site for full story ]]
Seek Thermal iOS
Ah, finally -my camera as arrived. I ordered my Seek Thermal Camera from Amazon for iPhone back in October 2014, and due to some issues between Apple and Seek over the Hardware Certification, the shipments had been delayed. Post by Seek Thermal. Since it is here I can now show you the unboxing of the […]
The post Seek Thermal iOS appeared first on Fryguy's Blog.
Rate my IOS?
Review schemes are useful for identifying good consumer products and applications. But that doesn’t mean that everything needs to prompt me to leave a review. Cisco has started prompting for reviews for IOS versions, but I’m not convinced it makes sense for network operating systems. Perhaps it will do one day when disaggregated hardware/software is the norm for network devices.
Reviews for Consumer Apps – no problem
I love the 1Password password manager. It’s a well-polished app, and has been great value. Part of making my life better means not annoying me with frequent prompts for review:
1Password never prompts you for a review. We value your workflow too much to interrupt it. If you feel generous and have a couple of minutes, please leave a review. It means the world to us.
I like the Pocket app too. It prompts me to leave a review every single time it gets updated, which annoys the hell out of me. But hey, it’s free, so maybe I shouldn’t complain too much.
Pocket and 1Password are examples of consumer applications in a competitive market. The barrier to switching is relatively low, and they live and die on reviews. In a crowded market, customers rely on reviews, and the Continue reading
How to define SDN?
Someone recently asked me what SDN is? Even though I have written multiple blogs related to SDN, I was not able to give a crisp answer which I was satisfied with. Since its fashionable to associate any new development in Networking to SDN, the definition becomes complex. In this blog, I will mention the different … Continue reading How to define SDN?
How to set up Cisco vIOS in GNS3 v1.x and get it working ?
Before we begin. There are many blogs out there that show you the method to do this. A great one is by Radovan Brezula atComware link-aggregation: LACP edge-port
Comware has 2 types of link-aggregation: static link-aggregation: no control protocol is used, based on the configuration, the link-aggregation member interfaces will be actively participating (Selected) in the link-aggregation at the moment the interfaces come up. dynamic link-aggregation: LACP control … Continue reading
How to build Mininet documentation
After installing the Mininet software-defined network simulator on a virtual machine, you may want to build the documentation. Documentation is available on the Mininet web site but, if you installed a beta version of a new development release or installed an old version, you may want to use the documentation specific for the version you are using.
Mininet documentation is built into the source code and can be generated using the doxypy program. This post details the simple steps required to install doxypy and other required software, and to build and view the documentation.
Install doxypy
Start the Mininet virtual machine and log into it via SSH. See my previous post about setting up the Mininet SDN Network Simulator virtual machine.
On the Mininet VM, run the following command to install doxypy, and supporting software packages:
$ sudo apt-get install doxypy doxygen doxygen-latex help2man
This could take a while because it downloads over one Gigabyte of data, such as fonts.
Build the documentation
On the Mininet VM, run the following command to build the documentation
$ cd ~/mininet
$ make doc
This builds a PDF version of the documentation named refman.pdf in the folder: ~/mininet/doc/latex/.