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CCNA Wireless – CCNA Wireless Notes Chapter 6

802.11 Frame Format

In a wired Ethernet network, the switch is not an active participant in communication at L2. In a wireless LAN, the AP is an active participant unless something like 802.11z, Extension to Direct Link Setup (DLS) is used.

To direct frames through the AP, the radio must have a MAC address, known as the BSSID.

802.11 frames can carry a maximum payload of 2304 bytes.

To support wireless communication, the Ethernet frame format is quite different compared to wired networks. The Ethernet frame starts out with a 2-byte Frame Control field, identifying the frame type, the direction the frame is traveling in and more.

Name Length (bits)
Protocol Version 2
Type 2
Subtype 4
To DS 1
From DS 1
More Frag 1
Retry 1
Pwr Mgmt 1
More Data 1
WEP 1
Order 1

In a common scenario with multiple clients associated with an AP that is connected to an DS, frames travel from clients towards the DS or from the DS towards the clients.

The frame motion is indicated by two bits, To DS and From DS, in the Frame Control field.

Frames sent by a wireless client will Continue reading

BrandPost: SD-WAN: What A Difference A Year Makes

SD-WAN is taking off.A year ago we announced 100 paying, deployed EdgeConnect SD-WAN customers. Earlier this month, we announced our 400th customer deployment, representing a quadrupling of our SD-WAN customer base in just 12 months.We are seeing our Unity EdgeConnect SD-WAN solution deployed globally, across a wide range of industries including financial services, healthcare, retail, manufacturing and transport. Our customers are simplifying and consolidating their WAN edge infrastructure, reducing operating costs and delivering an improved IT experience to their distributed workforce.To read this article in full or to leave a comment, please click here

Imagination adds safety, resilience to processor for IoT

Picture this: The networking stack on the main pump controller has crashed, and you need to reboot it -- but it's 20 meters underground, on another continent -- and there's no-one on site to hit 'reset'.Or you're bowling along the highway and one of the processor cores in your self-driving car gets zapped by a cosmic ray (yes, this could actually happen). The software can't tell whether the resulting error is a transient glitch or a hardware fault, so limits you to 50 kilometers per hour for safety: No fun with a monster truck hurtling up behind you.Chip designers such as ARM and Imagination Technologies are applying industrial safety design techniques to their processor cores so that they can get themselves out of situations like this. You could soon feel the benefit even if you don't run a subterranean pumping station in Azerbaijan, nor yet have a self-driving car in your garage.To read this article in full or to leave a comment, please click here

For Me the Internet Is Everything: Supporting Local Heroes in Armenia

Andranik, Sipan, Rudolf and Vahan have several things in common: they are young, they have dreams, they love music, and they love the Internet. The four of them are visual impaired. 

They met through the Internet Availability Center at the Cultural House of the Armenian Society of Blinds (ASB). 

I had the chance to visit the Center last year and Rudolf told me: “For me the Internet is everything. I cannot imagine what my life, my studies would be without it.” 

Ilda Simao

Worth Reading: The next five years of IPv6

The qualities of this deployment seem to me (at least) to best fit a logistic supply curve. Why? Because the economics application is often to model the rate of uptake of innovation, where we know it starts low (or zero) and it winds up hopefully at 100%, but it can’t go on forever — there is a foreseeable endpoint that might not be approached. The early days are slow, then things hit a critical mass and it seems to explode into action, and then things tail off again as the market saturates. —APNIC

The post Worth Reading: The next five years of IPv6 appeared first on rule 11 reader.

DHS and FBI issue alert about North Korean ‘Hidden Cobra’ hackers

Watch out for attacks by Hidden Cobra, aka North Korean government hackers, the DHS and the FBI warned in a joint technical alert. The US government didn’t tiptoe around the issue, instead pointing the finger of blame at North Korea for a series of cyberattacks dating back to 2009.Who the heck is Hidden Cobra? You probably already know about these cyber actors who are usually referred to as the Lazarus Group. Back in 2014 when the hackers targeted Sony Pictures Entertainment, the group was publicly referring to itself as Guardians of the Peace.To read this article in full or to leave a comment, please click here

DHS and FBI issue alert about North Korean ‘Hidden Cobra’ hackers

Watch out for attacks by Hidden Cobra, aka North Korean government hackers, the DHS and the FBI warned in a joint technical alert. The US government didn’t tiptoe around the issue, instead pointing the finger of blame at North Korea for a series of cyberattacks dating back to 2009.Who the heck is Hidden Cobra? You probably already know about these cyber actors who are usually referred to as the Lazarus Group. Back in 2014 when the hackers targeted Sony Pictures Entertainment, the group was publicly referring to itself as Guardians of the Peace.To read this article in full or to leave a comment, please click here

43% off Dyna-Glo DGO1176BDC-D Vertical Offset Charcoal Smoker – Deal Alert

For a truly distinct flavor, smokers offer you a wealth of custom cooking options. Simply choosing a different type of wood chip can vastly alter the flavor of whatever food you’ve placed on the grates. This Dyna-Glo smoker offers you not only these delicious benefits but those associated with using charcoal as your fuel source as well. This product’s vertical design includes six height-adjustable cooking grates and 1,176 inches of cooking space. The offset functionality of this smoker is designed to keep direct heat away from the food, helping to prevent food on the bottom racks from cooking too fast. The heavy-duty steel body construction features a high-temp, powder-coat finish that ensures a long life, while the smoker’s charcoal and wood chip tray is made with heavy gauged, porcelain-enameled steel for hours of maintenance-free cooking. It averages 4 out of 5 stars on Amazon from over 600 people (read reviews). The list price of the smoker is currently reduced 43% to a very reasonable $124.44. See this deal now on Amazon.To read this article in full or to leave a comment, please click here

$71 Off Samsung Chromebook Plus Convertible Touch Laptop – Deal Alert

The Samsung Chromebook Plus adapts to whatever you’re doing. Use it like a laptop to reply to emails or to work on a paper. When you need a break, flip the screen so you can play games or catch up on your latest book. Make your ideas personal and your notes clear with the built-in pen. Whether you’re doodling, sketching, or personalizing a photo, the built-in pen will help you get every detail just right. You can even use the pen to take a screenshot, magnify, or unlock the screen. The sleek metal body of the Samsung Chromebook Plus is comfortable to carry as a tablet and easy to fit in your bag while you’re on the go. Samsung's Chromebook Plus has 4GB of RAM, a 32GB hard drive, and a quad HD 12.3” screen (2400 x 1600). Its typical list price has been reduced by a generous $71 to $378.74. See this deal on Amazon.To read this article in full or to leave a comment, please click here

Most acute storage pain points, letdowns

Things don’t always go as planned with new technologies. Two new research reports document the struggles, disappointments and false starts that challenge enterprise storage pros as they modernize their infrastructures for digital business.451 Research asked enterprise IT pros to rank their most pressing storage pains. “Data/capacity growth” landed in the top spot, according to the firm’s research brief. “Meeting disaster recovery requirements” and “high cost of storage” ranked second and third, respectively, among survey respondents.“The core challenges in storage are shifting; public cloud is beginning to assume the burden of inexorable data growth, and the emphasis is moving to other areas, such as effectively managing data and storage across both on- and off-premises locations,” according to Simon Robinson, research vice president at 451 Research and author of the report, Top three storage pain points for enterprise customers.To read this article in full or to leave a comment, please click here

Shrubbery.net TACACS+ daemon and Junos

Axians Professional Services normally recommends using RADIUS authentication to our customers, but one of our customers uses TACACS.  We did some type-approval testing of new Junos release for them recently and had to set up a TACACS+ daemon in the lab to make sure authentication still worked following the upgrade.

Shrubbery.net very helpfully provide a TACACS+ implementation that you can download to a Linux host for this purpose, but the documentation is a bit light on their website, and what you find using Google is naturally somewhat Cisco-specific.  So here are some notes on getting a basic setup going with Shrubbery’s tac_plus daemon and Junos.  Maybe this will help someone else.

 

Create the Junos Config

First, you need to set up the Junos side of things.  You need to do three things:

  1. Create a tacplus-server in the config
  2. Add tacplus to the authentication-order
  3. Create a ‘local user’ account that has no password, but gives anyone belonging to it the appropriate privileges.

 

Create the TACACS server

axians@MX104-1-re0> show configuration system tacplus-server | display set

set system tacplus-server 192.168.3.237 port 49
set system tacplus-server 192.168.3.237 secret testing123
set system tacplus-server 192.168.3. Continue reading
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