Normally for these FFF articles I've taken to writing about new protocols as a way of introducing others to it and also edumacating myself about it. For this post I get all nostalgic and look at good old Enhanced Interior Gateway Routing Protocol (EIGRP).
If you're old enough (or interested enough) to have spent a lot of time messing around with the ASCII table then you might have run into a strange fact: it's possible to uppercase ASCII text using just bitwise AND.
And it turns out that in some situations this isn't just a curiosity, but actually useful. Here are the ASCII characters 0x20 (space) to 0x7E (tilde).
0123456789ABCDEF0123456789ABCDEF
+--------------------------------
0x20| !"#$%&'()*+,-./0123456789:;<=>?
0x40|@ABCDEFGHIJKLMNOPQRSTUVWXYZ[]^_
0x60|`abcdefghijklmnopqrstuvwxyz{|}~
It's immediately obvious that each lowercase letter has an ASCII code 0x20 more than the corresponding uppercase letter. For example, lowercase m is 0x6D and uppercase M is 0x4D. And since 0x20 is a single bit then it's possible to uppercase an ASCII letter by taking its code and applying AND 0xDF
(masking out the 0x20 bit).
Performing AND 0xDF
has no effect on the first two rows above: they, including the uppercase letters, are unchanged. Only the third row is affected. There the lowercase letters get uppercased but there's some collateral damage: ` { | } ~
change to @ [ ] ^
.
But if you know that a string has a limited character set then this trick can come in handy. Lots of old protocols Continue reading
(or Magical Things I Would Do if Hosts Weren’t Stupid) Introduction I’m a firm believer that many of the apparent problems in networking today are caused by stupid hosts. The hosts are stupid and, we are told, cannot be fixed. Instead, we are forced to add on more and more “intelligence” to the network. This […]
The post Smarter Hosts Would Make A Simpler Network appeared first on Packet Pushers Podcast and was written by Sam Stickland.
Excerpt: Coffee, doughnuts and networking. A perfect combination with Brocade, CloudRouter, HP, PacketZoom, Pertino, Juniper and much more.
The post Network Break 35 appeared first on Packet Pushers Podcast and was written by Greg Ferro.
Iwan Rahabok sent me a link to a nice vRealize setup he put together to measure maximum utilization across all uplinks of a VMware host. Pretty handy when the virtualization people start deploying servers with two 10GE uplinks with all sorts of traffic haphazardly assigned to one or both of them.
Oh, if the previous paragraph sounds like Latin, and you should know a bit about vSphere/ESXi, take a hefty dose of my vSphere 6 webinar ;)
Are you attending HIMSS 2015 in Chicago? We’ll be there with our newest partner! This week we announced our partnership with PSSC Labs. This partnership combines Plexxi’s SDN switching and control with PSSC’s high-performance compute and Cloudera enterprise. We’ll be showcasing the integrated solution, called the CloudOOP Big Data Pod, for the first time April 12 – 16 at HIMSS 2015. We’ll also be demonstrating how to effectively manage Big Data applications across a Hadoop cluster. Visit us at the PSSC Labs booth (#5284). We can’t wait to see you.
Below please find a few of our top picks for our favorite news articles of the week. Enjoy!
TechTarget: How SDN and SDS are shaping future clouds
By Jim O’Reilly
Tenants of clouds, whether public or hybrid, want the control mechanisms of a typical in-house data center. They don’t want to give up on virtual storage area networks and firewalls, access controls, governance and compliance and all the other security and control systems that go with ownership. But, at the same time, they want to see the promised agility, rapid scaling and cost effectiveness that brought them to the cloud in the first place.
Enterprise Networking Planet: The SDN-IoT Connection
Continue reading
Startup Avi Networks plans to push Layer 4-7 into the SDN age.
Did you miss out all the SDx news this week? No worries, it's all right here for you.