My readers are consistently asking me whether XMPP and OVSDB are control- or management-plane protocols (to make matters worse, publicly available information tends to be confusing).
For example, one of them wrote…
Read more ...It’s funny how you can work with something for years, but miss a small detail. This week I learnt about Skew Time for VRRP. The reason for it is completely obvious once you think about it, but for some reason the detail had escaped me for all these years.
VRRP sends out a “hello” multicast every <hello> seconds. Usually this is something like every 1 or 3 seconds. Unlike HSRP, only the current master sends out hello messages. This contains the current master priority & status.
The backup devices listen out for this hello message. If they think they have a higher priority, or if they fail to hear the hello message, they will assume the role of master.
Changing from backup to master because of one missed hello could cause network instability. There’s a common rule used for all keepalive-type messages, where backup devices will wait for three missed polls/keepalives before declaring something ‘down.’
VRRP is similar. It waits three poll intervals before declaring the master ‘down,’ and attempting to Continue reading
Long-time readers of my site know that my wife, Crystal, launched what is now known as Spousetivities at VMworld 2008. Since that time, she’s been able to organize activities for hundreds of companions at dozens of events around the world. This year she’s adding another event to the roster: DockerCon 2016 in Seattle!
That’s right, Crystal and Spousetivities will be available at DockerCon in Seattle. Here’s a quick look at some of the things she’s got planned:
All in all, it sounds like a great set of activities. Also, I’m very impressed that DockerCon is also offering childcare during the event. Between Spousetivities offering kid-friendly events both days and DockerCon providing childcare, there’s no reason not to bring the family with you to Seattle.
If you’re interested in signing up for any Continue reading
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Maybe I’m getting too old for my own good. Or maybe studying philosophy is making me older. Here in the US, though, it is Memorial Day, a day where people normally grill burgers and dogs, throw a few back, and forget to ask why. It’s just another day off, and days off are good for—well, for something.
Memorial Day, in the US, stands in memorial for those who fought—and, specifically died—for our freedom. But what is freedom? In my world, there are two types of freedom: freedom from, and freedom to. Two pieces this week made me think through this difference once again, and how we are increasingly confusing the two concepts.
But the big thing that changed this week is a Google home device is no longer a theoretical possibility. It’s here. And on a sunny day at the outdoor amphitheater, just a half mile away from the Googleplex, the audience watched as a video showed the device at work in the home of a typical American family. There was laughter when the dad broadcast his playlist into every room in the home, waking up his sleeping children — and then later remotely turned on the lights to make Continue reading
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Researchers develop Chronos, a new method for determining the location of WiFi devices with decimeter accuracy.
I’ve got a problem with sagging cables, and I’ve got a simple solution. Examine the side-by-side images below which show the same fiber connection between a switch and a firewall. The image on the left shows a sagging cable which crosses in front of the switch in the rack unit just below it.
As you may know, this cabling install is a violation of the 167th rule of networking:
Thou shalt contain your cables to your own rack unit and shalt not, under any circumstances, impede access to other rack units or blades.
The image on the right ticks the box for me. There’s no room for a dedicated 1RU horizontal cable manager, but there is room for a zero-RU strain relief bar (as seen below). The result is a relatively neat cabling job. It’s no work of art, but it’s functional.
A strain-relief bar is a cheap metal bar that you can bolt on when you rack-mount your switch. It allows you to velcro your fiber patches to the bar, taking the strain to help prevent breaks and preventing the dreaded cable droop. You should, of course, take care to ensure you don’t block access to any field-replaceable units, cards or ports on your network device.
The strain-relief bar Continue reading
I’ve got a problem with sagging cables, and I’ve got a simple solution. Examine the side-by-side images below which show the same fiber connection between a switch and a firewall. The image on the left shows a sagging cable which crosses in front of … Continue reading
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