There’s a Difference between Scaling and Not Being Stupid
I was listening to one of the HP SDN Packet Pushers podcasts in which Greg made an interesting comment along the lines of “people say that OpenFlow doesn’t scale, but what HP does with its IMC is it verifies the amount of TCAM in the switches, checks whether it can install new flows, and throws an alert if it runs out of TCAM.”
Read more ...RFCs You Should Know: 5218
Quite often RFCs in the “earlier days” discussed not only process but also design. Looking back now, considering the complexity of the network engineering world, these RFCs might seem even a little trite. But these “architectural RFCs” often still carry thoughts and records of experience that are important, even if they aren’t so much followed […]
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The post RFCs You Should Know: 5218 appeared first on Packet Pushers Podcast and was written by Russ White.
Five Functional Facts about EIGRP
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).
The oldest trick in the ASCII book
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
Smarter Hosts Would Make A Simpler Network
(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 […]
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The post Smarter Hosts Would Make A Simpler Network appeared first on Packet Pushers Podcast and was written by Sam Stickland.
Carrier Supporting Carrier implementation on Cisco routers using GNS3 – Part 1
Hello people! I’ve been a student of networking for the past 9 years working in ISP and vendor test environments over the span of myNetwork Break 35
Excerpt: Coffee, doughnuts and networking. A perfect combination with Brocade, CloudRouter, HP, PacketZoom, Pertino, Juniper and much more.
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The post Network Break 35 appeared first on Packet Pushers Podcast and was written by Greg Ferro.
Cisco NXAPI
Earlier, I had written about Cisco NXOS device configuration/monitoring using Python and OnePK. Recently, I came across NXAPI approach to configure and monitor NXOS devices. NXAPI uses either http/https to connect to NXOS devices and talk using NXOS CLI. For configuration, CLI is encoded in XML/JSON. For monitoring, CLI is encoded in XML/JSON and the … Continue reading Cisco NXAPI
Embrane – What do they do?
Cisco recently acquired Embrane. I tried to dig deep to answer some questions I had and this blog is a result of that. What does Embrane do? Embrane provides L3-L7 Network services and lifecycle management of L3-L7 Network services. Embrane has their own version of Firewall, Load balancers etc and they also partner with vendors … Continue reading Embrane – What do they do?
Cisco UCS Platform Emulator
Earlier, I had written a blog on Cisco UCS automation using Python SDK. At that time, I used real UCS system to test my scripts. Cisco UCS PE(Platform Emulator) emulates UCSM(UCS Manager) software and we can run this as a VM. Different types of hardware(Fabric Interconnect, FEX/IOM, Servers, adapters, power supply) can be added to … Continue reading Cisco UCS Platform Emulator
Are your ESXi uplinks saturated?
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 ;)