I’m not a “lifelong” Windows user. My first computer was a Commodore 16.

What? It counts.

Then there was a VIC 20, Spectrums, Amigas, (ah, Commodore, where art thou?), but I never owned a C64. I’m still bitter about that.

Anyway, eventually I got a 486 and I upgraded from MSDOS to Windows 3.1.
Looking back, I’m not sure what I used it for. College probably, writing Pascal, and er, wordprocessing the reports to go along with my Pascal projects.

It’s hard to imagine doing anything with a computer that wasn’t much cop at playing games, and didn’t have internet.

I’ve never had a problem with Windows. Supporting Windows pays my mortgage.
Well, there was Windows ME, but no one likes to talk about that. We all make mistakes.

I have cheated on Windows in recent years with Linux, but always drifted back to Windows when figuring out how to do something in Linux took longer than a reboot to Windows.

My recent Linux “thing” lasted about 2 years, and ended when the laptop decided that if it wasn’t on mains, it wasn’t going to start. And if it was on mains and someone dared to unplug for a moment, it would go a bit dead.

Eventually, with a thirsty digicam and disk space running low, one of the operating systems had to go, and that had to be Linux. I couldn’t be bothered to spend hours on the internet working out how to keep the sodding thing on.

The laptop though, it is tired. Flash components make it barf CPU cycles, and despite a healthy dose of RAM, it’s gone a bit crap.

So I decided to buy a new computer.
And for some reason I bought a mac.

So, I tried Verizon out for roughly 23 days so far. I’m 90% sure I’m going to switch back to T-Mobile.

The Service:

The weird thing is that the service wasn’t any better than T-Mobile’s. I only really saw a difference when I was in the basement of my work, where T-Mobile only gave me 1 bar and Verizon gave me all 4. I’ve had more dropped calls while on Verizon than I’ve ever had on T-Mobile, which is also very surprising to me. I guess it helps that I live in a fairly large metropolitan area, and T-Mobile seems to have those covered pretty well. I don’t ever go home, where I believe Verizon would indeed have an upper hand.

The Phone:

Wow, is all I have to say. I’m in love with the Motorola Droid. It’s really the only reason I’m not 100% sure I’m switching back yet. But, if these people are to be believed, I may have luck with a Motorola Sholes (Motorola’s codename for the Droid) on T-Mobile. I’ll take my chances.

Trivia: CDP

• SW1 and SW2 should see each other as CDP neighbors via SW3
across the routed link that connects them.

Diagram:

SW1———-f0/1–SW3–f0/2———SW2

Answer:

SW2:

interface FastEthernet0/1
l2protocol-tunnel cdp
no cdp enable

interface FastEthernet0/2
l2protocol-tunnel cdp
no cdp enable

That’s it!

Well, after months of reading, rentals, questions, and consultations, I’ve decided to jump the Nikon ship and buy a Canon 7d.  As my goal is short/medium format journalism and documentary pieces the value I will get from the 7d’s still and video feature-set has no parallel within Nikon’s current offerings.

Many of my Nikonian friends have expressed their disappointment (or plain disgust) at my leaving the Nikon ecosystem for Canon; and have posed many arguments such as build quality, lens selection, and strange backward focus rings as arguments against my position.  However, after renting the 7d for a weekend and shooting some stills and video I can attest that the build quality of the 7d is superb, a mite lighter than the 5d mkii but very solid.   With regards to lenses.  I will have to learn the Canon system for lens quality but third-party manufacturers make identical lenses and slap the custom Canon/Nikon mounts on them.  Thus, I’m not worried about lens selection, though it will be hard to part with my primes.

That being said, my new adventure begins.  Stay tuned.

Truth will out!

–

Some sites that helped me to make my decision

here, here, here, and here

–

B.

From the moment he said he was on his way, I thought about it.

We planned to do some role play. Run of the mill, over the knee, hand, hairbrush, maybe a little bath brush. Some good pretend lecturing and a little corner time for the pouty little girl.

You know, the usual.

And then he went over my knee, and because he’s a spanker, and a male one at that, I only needed to employ my hand. I’m getting good at the scolding, too.

At one point, the wind rustled a bunch of stuff and it sounded like someone was in the apartment, and Mr. Scardeycat jumped off my lap alarmedly, and we checked it out. The wind.

He didn’t want to get back over my knee, so I had to make a decision.

I wasn’t sure. I knew I needed it, but there were a few things to consider.

One: It would freaking hurt and I’d be ouchy and regretful rather quickly.

And two: It’s not my paddle. I’m holding on to it for a friend. But given the offense, I didn’t think he’d mind. In fact, he’d probably want to use it on me. Repeatedly.

“Hold on,” I said, opening the closet door. “I need to ask you to do something for me.”

He looked at me expectantly, as I pulled it off the shelf and handed it to him, in its soft black bag. “Wow,” he said, slipping the cover off.

“Yeah. It’s beautiful. But be careful with it. It’s not mine.”

He nodded, waiting for me to continue. “I, uh, need a little motivation.”

He raised his eyebrow. “Yeah. I haven’t been taking very good care of myself. And I need a little… help, Sir.”

He pointed to the floor in front of him and I immediately stood where he directed. I looked up at him and the seriousness in his eyes told me this problem would be appropriately dealt with.

And it was.

Decided to switch to wordpress instead of my old LiveJournal account as I prefer the dashboard here. So all my blog posts will appear here from now on.

Apple’s “I’m a Mac/I’m a PC” commercials never get tiresome. They’re quite charming actually. I’ve don’t think I’ve watched more computer ads other than those. I’m surprised there is still so much material they can smack together to continue them.

Advertising on the web is still tricky business – to execute it successfully. Once in a while there are some real gems for web ads. This is one them. I’ve seen Apple’s advertising use flash to “shake-up” the layout of a website for the iPod touch, as well as John Hodgman climbing all over the NY Times front page, and this one is no exception. One has to really wonder how these ideas are brought to life.

Switching Mode Power Supply atau yang sering disingkat menjadi SMPS adalah teknologi di bidang catu daya (power supply). Selain SMPS ada teknologi lain yang lebih dulu ada yaitu linear power supply.

Apa perbedaan utama antara kedua teknologi ini? Ditinjau dari segi bahasa, SMPS berarti catu daya yang menggunakan prinsip saklar (switch) dalam operasinya, sedangkan linear power supply (LPS), sulit diartikan dari segi bahasa, namun secara sederhana bisa diartikan sebagai tanpa-saklar atau aliran kontinyu.

Dari segi bahasa bisa dibedakan prinsip kerja dari kedua teknologi tersebut, yaitu dengan saklar dan tanpa saklar. Kemudian apa konsekuensi dari perbedaan prinsip tersebut?

Jika dianalogikan dalam pengisian wadah dengan air, teknologi SMPS menerapkan pengisian air on demand (jika wadah telah penuh maka keran dimatikan dan sebaliknya), sedangkan LPS menerapkan pengisian air kontinyu (tidak peduli wadah telah penuh atau kosong air akan menyala terus). Dari analogi tersebut jelas SMPS akan lebih efisien dalam penggunaan air dibanding LPS.

Ya, teknologi SMPS lebih efisien dalam proses regulasi energi listrik dibandingkan LPS. Konsekuensinya energi yang diboroskan oleh perangkat SMPS akan lebih rendah, yang berakibat panas perangkat yang lebih rendah pula. Efisiensi dari teknologi SMPS dapat mencapai 90%, yang relatif tinggi jika dibandingkan dengan LPS hanya 50% – 60%.

Keunggulan dari SMPS menyebabkan adopsi teknologi ini sangat pesat, hampir seluruh perangkat elektronik rumahan saat ini memanfaatkan SMPS. Perangkat mobile juga mendapatkan keuntungan yang sangat besar, karena ketahanan penggunaan baterai lebih baik relatif terhadap LPS.

About this time last year my broadband provider had no problems that caused me lengthy periods looking at “Connecting…” every time I opened a new browser tab. Nothing to do with browser tabs. The time it took for TelstraClear’s servers to lose interest in serving me just happened to be about the same amount of time it usually took for me to find something on a page I was reading that I wanted to follow-up on another site.

I think it was about mid March when they sent an extremely non-committal letter offering a discount on degraded services while they did a “major upgrade”.

The problem that had never existed did go away about the time they announced their upgrades completed. The service after the upgrade has been no better than it had been before the non-existent problem and the alleged upgrade.

Fine. I am so over getting worked up over such nonsense. But don’t do it again.

They’re doing it again. Something between their modem and the world at large goes to sleep for a few minutes after any period of more than about five minutes inactivity. Most of the rest of the world is not currently suspect, as this almost certain non-problem also affects email.

Never mind. Just for now I’m enjoying occasional high-speed broadband.

Broadband is a very interesting thing. I never cease to be amazed at how much data can be crammed into a piece of copper. With fiber optic and wireless is relatively easy to visualise different wavelengths and frequencies “layered” so that many channels can exist simultaneously – lots of parallelism. With copper, coming from the days of 110 baud comms, the extraordinary tricks played to load every cycle with more data and to cram more cycles into every second simply boggle my mind.

I like to think of a correctly functioning brain as a broadband device. In the course of our day’s activitities it will rev up or chill as the needs dictate. That’s in a correctly functioning brain. That’s in a correctly functioning brain in an environment that mostly makes sense. Unfortunately for most of, our brains spend a lot of time in non-optimal states.

There’s a whole lot of factors that seem to be conspiring to lead many of us to dwell more in certain ranges of brain activity than is desirable. Society, our environment, mostly doesn’t make sense. We spend far too much time in a state of alarm – too much demanding our urgent attention. There is also a strong predilection for high adrenalin recreation – be it base jumping or MDK video games. The popularity of prescription and non-prescription stimulants suggests that a good proportion of us are hooked on a degree of speed. The necessity to bring so many kids “up to speed” with Ritalin et al also suggests that we are being required to function at a pace not wholly natural to our species.

The ideal of “the good life” is unattainable to those who can’t keep up the pace, leading to a special sense of non-belonging and failure that may manifest as any of the many mental illnesses, so-called.

Then there’s those who look at what most people are scrambling for and fail to see the point/value. When reality objectively sucks in terms of a set of well established values, all manner of escapist strategies may be adopted, ranging from any of the aforementioned mental illnesses and throwing in substance abuse as well.

Some can keep up the pace, but usually at the expense of anything that could be confused with a healthy relationship with others.

The wonderful thing about all this is that all of these behaviours reflect with statistical significance in our EEG output. Many people experiencing depression will exhibit low beta and or a beta/alpha lateral imbalance. Many people experiencing ADD will show low beta and excess theta. Alcohol and cannibis addicts often exhibit low theta. So it goes on.

Is it the correct strategy to try to pump up the deficiency by injecting it from outside? Hmmmm. Mebe. Superficially it seems this may work. Results from neurofeedback where they cultivate the desired frequencies with exercises suggest that correcting the deficiency is a good thing.

Thing is, I still haven’t seen one shred of evidence that exposure to a particular brainwave-range frequency, in the absence of any other factors, has the slightest influence on human thought or behaviour. There’s a whole heap of “other factors” that have not been adequately excluded – placebo and expectation being among them. Neurofeedback is a closed loop system – feedback makes all the difference, it makes the process ”self proving”.

There are some direct, physiological effects – notably release or inhibition of various hormones – that have been directly associated with particular frequencies, but as far as I know, this information is derived from the natural activity of the brain. The supposition that mere exposure to said frequencies will have the same effect as has been observed when they occur naturally in the brain has not been adequately demonstrated.

I know I’ve said most of this before, several times, but it so important that it’s worth saying quite a few different ways… effectiveness of AVS/entrainment is more dependent on what you are consciously doing with your brain than on session content. A lot of good work can be done by training in each of the different “thought bands”. As suggested in an earlier paragraph – there a lot of reasons why a lot of us probably do have some anomalous deficiencies and excesses. I’ve had to deal with some of mine with Prozac, but them’s is the breaks.

Now that I have, with AVS, chemistry and a lot of different therapeutic and recovery experiences, got a brain that’s well-behaved most of the time, I can get into serious optimisation techniques.

I still enjoy sleep induction, anxiety reduction, pain relief and a few other fixed frequency sessions, but my interest lies in broadband applications – ways to interest as much of the brain as possible. My energies are directed not so much into finding just the right frequency to stimulate health, wealth, wisdom and popularity, but to exercise every neuron in my body, to find out what unsuspected treasures are stashed away in obscure, barely referenced, regions of the memory and to establish fresh new connections. When I think, I want to do so with the use of every shred of information/experience stashed away between my ears. To this end I write sessions that make my brain do unusual things. Training a brain to exhibit a particular frequency is akin to teaching a dog to sit – it knows how to do it, all you’re doing is establishing a tightly specified condition under which to do so. Frequency Independent Sessions are more like teaching a dog to sit whenever you want it to without having to give it any specific instruction.

Early on in the piece, research kept revealing single frequency cognitive/behavioural association. As time is passing more and more complex frequency relationships are being observed. One of the best documented, and of great interest to me, is the theta/gamma connection in cognitive binding. I’ve written a number of sessions to explore this, and I’ve been thrilled to bits with the results. I’ve not had a lot of feedback from others who have tried these sessions, but more than a few have reported “nothing happened”. Absolutely correct!!! These sessions are not structured in the way a “normal” targeted frequency session is. The only immediate perceptible effect is likely to be an assault on aesthetics. The readily recognised sensations associated with the distinct frequency ranges are unlikely to be felt. These sessions can be range biased - great for theta/delta meditation/contemplation as they’re not conducive to sleep as so many conventional low-frequency are.

It’s now way to late to cut this particular long story short, but I think I’ve reached the point where I’d better make my point – I’m not sure if my analogy has survived the flogging.

Lots of us are running on switched a single frequency basis. We switch between modes of thought. This results in relatively inefficient serial processing and often we switch too slowly, meaning that some decisions are made in the mental light of earlier circumstances, or too quickly, in which case anything can happen. Outcomes depend a lot on our “mood” at the time “intent” and “action” impulses occur. We often think we’re “multitasking”, but we’re timeslicing, not multiprocessing, not even multithreading.

A flexible brain is a broadband brain. A broadband brain “sees” all known facets of the matter at hand simultaneously without prejudice or favour. A broadband brain can home in on a detail, do it’s business and then zoom back out to the big picture. A broadband brain is much easier to keep satisfied, it doesn’t get bored as easily, it’s good at finding constructive ways to amuse itself.

Chances are that I’m representative of a very small demographic. There’s little likelihood that there will be a large number of people whose brain is structured sufficiently similarly to mine to fully benefit from sessions that I have developed and optimised for myself, but there will be some, and that’s why I’m developing AVS content for commercial distribution.

Cheers,
Craig

I have wanted to post, but, as in life lately, I am at a loss for words.  There is major shifting going on inside of me, but I don’t know how to articulate it.  Yet.

I am still isolating myself quite a bit, but I think this is okay for now.  I am not numbed out anymore, and I am feeling more connected to the people around me than I was a few weeks ago.  I would like to be able to talk and share more than I am, but I know it will come.  I would like to be a better spouse than I am, and I know Husband will read this, so let me say this to you, my love:  I miss you, and I am wanting to hear the tales of your days, and I am on my way back, and I love you more than tongue can tell.

So, the shifting.  I will try to explain, as best I can.

I started this blog with an acknowledgment of parts, and dissociative identity disorder.  But in the back of my mind, I was holding on to this belief that that wasn’t really my problem, that this was all some game I was playing (subconsciously).  Because in order to be that messed up, I figured, I would have to have something really rotten in my past, and hey, that’s not me.  I continue to hang onto that belief at times, but the thread by which it hangs becomes more and more frayed.

My “regular life,” as I call it–my job, my time with Boo and Husband–remains pretty unchanged.  But my life inside my head is wildly different at times, particularly at night, after I put Boo to bed.  And my life in therapy–well, that’s just a whole different world from what I’ve experienced before.  Because it’s not just me going to therapy.  It’s all of them (the parts) coming along as well.  Which is just very, very weird to me.  (I don’t mean “weird” as a bad thing–just meaning that it feels strange because I’m not used to it.)  T sees them, talks to them (which always automatically makes me come back in front, so they don’t get a chance to respond, which is kind of humorous at this point because it’s so predictable), listens to them (they do talk, just not in response to her), and can somehow tell them apart (which is really freaky to me).  She is so, so smart and observant.

The more they are seen and heard, the more they seem to have to say.  But talking is difficult on the best of days.  So they write.  Or rather, I write for them.  I’m the typist, at least.  T, who must be a workaholic or something, allows me to email as much as I/they want.  This (emailing with therapists) is something that is controversial, and I can see both sides of the issue, but in my case, I am grateful for it because it really allows the parts to open up WAY more than they can in person.  A journal would do the same thing, but the nice thing about email is that T can read it before my session, and she knows where I am as a result.  She doesn’t usually respond, and when she does it is very brief, so it’s not “email therapy,” so to speak.  She uses the emails as a guide for what to talk about in session, and it’s very helpful.

When I write her, it is usually at night.  I will know that I sent email, and I will often try to remember what I wrote before I check my sent mail, but, truth be told, I usually only remember parts of what I have written.  It’s like I will know that Ann sent an email, but I won’t know what it said.  (And no, I am not under the influence of anything.)  When I read it, I will have an “aha” moment of remembering what I’d written, but I can’t come up with it on my own.  Maybe that isn’t so strange, but it feels pretty strange to me.

So, what is going on is that, in my therapy life, major things are happening.  Parts are coming out and sharing stuff–not anything dramatic or any details of abuse, but just feelings and thoughts.  They are testing the waters.  They are sometimes trusting, sometimes wary, sometimes angry, sometimes terrified, sometimes sad.  Etc.  I am trying to just go with the flow, and type the thoughts out as best I can, and hit “send” before I can second-guess myself or them.

Sometimes it is almost unbearable to feel what a part is feeling.  Sadness is hard, but anxiety/fear is the worst.  One night last week, I was absolutely coming out of my skin.  I was aware that I was not in fact dying, but it really felt like I was dying.  Just thinking about it makes me feel a bit wiggy.  Sometimes I just feel small, but not scared or sad.  The part I am calling Ann is, I think, quite happy much of the time.  She is as crazy about T as one person can be about another, I think.

So, yeah, I guess I do actually have “parts.”  I guess I don’t know everything they know, but I am trying to listen and be open and not squash them out of fear.  I am trying to accept all of this without concluding that I am crazy.  I am trying to stop waging war with myself over what is or isn’t real.  I am trying to walk this path, one step at a time.  I think I’m doing an okay job of it.

Thanks for reading.

Yeah I agree.  I know how he feels.  One day I will write a post about my different experiences with browsers and why I have kept moving.  Click here.

Multi layer switching adalah cara dimana menyusun perangkat network switch menjadi beberapa tingkatan dikarenakan end user yang terkoneksi ke dalam suatu jaringan memiliki jumlah yang banyak, sehingga kita perlu melakukan trunking (menyambungkan switch satu dengan switch lain) antar network switch secara bertingkat.  Di bawah ini merupakan contoh multi layer switching yang disimulasikan dengan program Packet Tracer milik Cisco.

Pada gambar di atas network switch tersusun atas 3 layer (tingkatan) yaitu Core Switch sebagai layer pertama, Distribution Switch sebagai layer kedua dan Access Switch sebagai layer ketiga.  Fungsi Core Switch adalah sebagai network switch yang menggabungkan beberapa device network switch menjadi satu kesatuan (integrated network).  Distribution Switch berfungsi sebagai penghubung antara Core Switch dengan Access Switch.  Access Switch berfungsi sebagai penghubung antara network dengan computer end user.  Jadi kesimpulannya dengan menggunakan metode multi layer switch kita dapat melakukan extend (perluasan) jumlah komputer yang terkoneksi ke dalam jaringan. Contoh susunan 3 layer network switch di atas dapat dikembangkan lagi menjadi beberapa layer ke bawah tergantung dari kebutuhan jumlah jaringan.

Command line CISCO untuk switch trunking dipergunakan untuk menyusun multi layer switch seperti di atas.  Caranya adalah masuk ke dalam mode configurasi switch kemudian akses port interface switch yang akan dipakai untuk trunking dan set mode port tersebut ke trunking.  Contohnya command line nya adalah sebagai berikut :

Di atas gw mengkonfigurasi Core Switch (CISCO 3560) agar port fast ethernet nomor 1 memiliki mode trunk, karena interface fast ethernet nomor 1 berhubungan dengan Distribution Switch 1 interface fast ethernet nomor 24.  Di bawah ini adalah contoh konfigurasi Distribution Switch 1 port fast ethernet 24 untuk mode trunk.

Dengan cara-cara konfigurasi seperti di atas kita telah menghubungkan / melakukan trunking antar 2 network switch. Untuk menghubungkan network switch yang lain sama halnya seperti cara di atas.  Kesimpulannya adalah apabila kita ingin menghubungkan device network switch satu dengan yang lainnya, kita harus melakukan set mode trunk pada port interface yang dipergunakan untuk penghubung antar switch.

Vlan adalah fasilitas yang diberikan untuk melakukan pengelompokan jaringan besar menjadi segmen-segmen jaringan kecil.  Ilustrasi penggunaan vlan adalah seperti ini, biasanya apabila kita mengimplementasikan sistem network di dalam suatu perusahaan kita harus membatasi akses jaringan suatu unit kerja agar tidak berkomunikasi dengan unit kerja yang lain.  Caranya adalah kita mendefinisikan vlan untuk masing-masing unit kerja; misalnya vlan 101 dengan nama alias vlan_keuangan untuk unit keuangan, vlan 102 dengan nama alias vlan_sdm untuk unit sdm, vlan 103 dengan nama alias vlan_operasional untuk unit operasional, dst.  Dengan adanya pendefinisian vlan untuk masing-masing unit kita bisa membuat seolah-olah network unit satu tidak bisa berkomunikasi dengan network unit lain walaupun network sudah terintegrasi. Di bawah ini merupakan contoh cara pendefinisian beberapa vlan pada network switch.

Untuk multi layer switch pendefinisian vlan seperti di atas dilakukan pada masing – masing switch, sehingga setiap switch pada network mengetahui vlan apa saja yang ada di sistem network tersebut. Untuk mengetahui vlan – vlan apa saja yang telah kita daftarkan dalam suatu device network switch kita dapat mengetik command “show vlan brief” pada mode non configurable, contohnya seperti di bawah ini.

Dapat dilihat di atas ada beberapa vlan yang walaupun kita tidak definisikan tetapi sudah ada di dalam daftar.  Vlan – vlan tersebut dinamakan default vlan.  Berdasarkan data dari “show vlan brief” di atas kita melihat bahwa port interface fast ethernet nomor 1 – 24 dan port interface gigabit ethernet 1 dan 2 akan masuk dalam kategori vlan 1 (vlan default).  Kita dapat merubah beberapa port interface ke vlan-vlan yang telah kita definisikan.

Misalkan kita memiliki topology (struktur network) sederhana seperti di atas, dimana satu switch dipakai untuk 2 unit CPU bagian keuangan, 1 unit CPU bagian SDM dan 1 unit CPU bagian operasional. PC no. 1 keuangan terkoneksi pada port fastethernet no.1, PC no. 2 keuangan terkoneksi pada port fast ethernet no.4, PC SDM terkoneksi pada port fast ethernet no. 2 dan PC operasional terkoneksi pada port fast ethernet no.3. PC 1 dan 2 Keuangan akan ada di vlan 101 (artinya port fast ethernet no.1 dan no. 4 akan kita set masuk ke dalam vlan 101), PC SDM akan ada di vlan 102 (artinya port fast ethernet no. 2 akan kita set masuk ke dalam vlan 102) dan PC Operasional akan ada di vlan 103 (artinya port fast ethernet no. 3 akan kita set masuk ke dalam vlan 103).  Cara melakukan konfigurasi pada switch nya adalah sebagai berikut.

Masuk pada port interface yang akan diset. Set mode port tersebut ke mode access.  Mode access dipergunakan apabila port switch langsung dihubungkan ke komputer end user, lain halnya apabila dihubungkan ke switch lain mode harus di set ke trunk.  Lalu lakukan pemindahan port interface ke vlan.  Setelah melakukan set mode port interface fast ethernet, lakukan setting IP address pada masing masing komputer dengan ketentuan sebagai berikut :

PC 1 keuangan = IP : 10.1.101.11, subnet mask : 255.255.255.0, gateway : kosong (karena kita tidak menggunakan sistem routing)

PC 2 keuangan = IP : 10.1.101.12, subnet mask : 255.255.255.0, gateway : kosong (karena kita tidak menggunakan sistem routing)

PC SDM = IP : 10.1.102.11, subnet mask : 255.255.255.0, gateway : kosong (karena kita tidak menggunakan sistem routing)

PC Operasional = IP : 10.1.103.11, subnet mask : 255.255.255.0, gateway : kosong (karena kita tidak menggunakan sistem routing)

Setelah semua PC diset IP address lakukan test ping ke beberapa komputer.  Contoh di bawah ini gw melakukan test ping dari PC 1 Keuangan ke PC 2 Keuangan ternyata ada reply karena berada pada vlan yang sama, sedangkan pada saat test ping dari PC 1 Keuangan ke PC SDM ternyata “Request Timed Out (RTO)” karena berada pada vlan yang berbeda.

Kesimpulannya adalah dengan memanfaatkan vlan kita melakukan pengelompokan jaringan menjadi beberapa segmen yang membatasi akses network antar satu bagian ke bagian yang lain.  Dalam satu network switch bisa terdapat 1 atau lebih jumlah vlan, tergantung dari kebutuhan network.

Inter Vlan Communication adalah mekanisme dimana melakukan setting agar network di dalam vlan satu dapat berkomunikasi dengan vlan yang lainnya, walaupun sebenarnya dengan adanya vlan membatasi ruang gerak komunikasi antar network. Inter Vlan Communication ada dikarenakan adanya beberapa kebutuhan agar suatu PC di vlan tertentu dapat berhubungan dengan device pada vlan network yang lain, misalnya PC di vlan Keuangan harus berkomunikasi pada PC Server di vlan Server.  Untuk melakukan mekanisme Inter Vlan Communication kita harus meng-enable mode ip routing. Di bawah ini gw memberikan contoh topology sederhana yang menyangkut Inter Vlan Communication.

Di atas merupakan topology sederhana untuk mempraktekkan Inter Vlan Communication.  Mode IP Routing hanya ada pada Device Router dan Device Switch (tidak semua switch CISCO).  Pada contoh di atas saya menggunakan device network switch Cisco 3560. Ada 3 vlan yang didefinisikan pada device switch yaitu vlan 100 sebagai vlan_management, vlan 101 sebagai vlan_keuangan dan vlan 102 sebagai vlan_sdm.  Langkah – langkah konfigurasi switch nya adalah sebagai berikut :

1. Enable mode IP Routing pada Switch 3560

2. Buat daftar vlan

3. Set vlan dengan IP address

4. Rubah mode port interface fast ethernet sesuai dengan vlan nya masing – masing (pada contoh port 1 sebagai vlan 101 dan port 2 sebagai vlan 102)

Setelah mengkonfigurasi network switch lakukan setting ip address ke komputer dengan contoh pengalamatan sebagai berikut :

PC 1 = IP : 10.1.101.11, subnet mask : 255.255.255.0, gateway : 10.1.101.1 (sesuai dengan ip address vlan 101)

PC 2 = IP : 10.1.102.11, subnet mask : 255.255.255.0, gateway : 10.1.102.1 (sesuai dengan ip address vlan 102)

Kemudian lakukan test ping dari PC 1 ke PC 2 dan lihat apa yang terjadi.

Ternyata setelah dilakukan test ping dari PC 1 (vlan 101) ke PC 2 (vlan 102) ada reply dari PC 2, maka inilah yang disebut dengan Inter Vlan Communication.  Bagaimana kalau seandainya ada switch penghubung antara Switch Cisco 3560 dengan PC seperti gambar di bawah ini.

Jawabannya adalah seperti langkah – langkah di bawah ini :

1. Set terlebih dahulu mode trunk pada interface yang dipergunakan untuk menghubungkan antara Switch 3560 dengan Switch 2960.

2. Definisikan vlan di Switch 2960 sama dengan Switch 3560 (tidak perlu set ip address untuk masing-masing vlan di Switch 2960).

3. Ketik command line “ip default-gateway 10.1.1.1″ agar traffic dari PC menuju ke Switch 2960 dilarikan ke Switch 3560.

Apabila switch 2960 selesai di konfigurasi, set kembali ip address PC sama seperti di atas, kemudian test ping dari PC 1 ke PC 2 dan terakhir test tracert untuk mengetahui jalur traffic.

Dapat di lihat dari contoh test ping di atas bahwa ada reply dari PC 2 ke PC 2.  Jalur dari test tracert juga menunjukkan traffic melalui ip 10.1.101.1 (ip address pada vlan 101 yang di set di switch 3560) terlebih dahulu baru sampai ke PC 2.

Sekarang pertanyaannya adalah bagaimana kita melakukan block traffic dari vlan – vlan tertentu yang seyogyanya metode vlan adalah untuk blocking traffic network.  Jawabannya adalah menggunakan fasilitas “Access List”, tapi bagian Access List gw akan bahas pada postingan yang berikutnya ……. kalo sempat …… hehehe

Ini link simulasi latian packet tracer gw yang gambar paling atas, kalo mau coba silahkan download dan buka di packet tracer 5.

Download

Maju terus IT Indonesia !!!!!!!!

Some STP Basics
On most Cisco Catalyst switches, STP is enabled on all ports by default.   Port initialization requires upwards of 30 seconds to complete, and can take as long as 50 seconds.
This thirty second “delay” can be attributed to the time required for the port to transition from Listening to Learning and finally to Forwarding.
The Listening and Learning transitions each require about 15 seconds.
This transition period can be painful for end users waiting to gain access to the network.  To the untrained IT person it can be misdiagnosed as “some sort of network issue”.

PortFast to the Rescue
Portfast shortens the Listening and Learning states allowing the link to transition to the Forwarding state in as little as three seconds.
This translates to quicker access to the network for the end user when they power on their PC, connect a laptop to a wired port, etc.
Enabling PortFast does not disable STP on the port, it simply allows us to get to the Forwarding state much faster.

Let’s enable PortFast on switch ports 1 – 4 using the spanning-tree portfast command.  IOS provides a reminder of the possible consequences.

Looping ports Fa0/2 and Fa0/3 reveals that we still have adequate loop protection as Fa0/3 transitions to a Blocking state within ~2 seconds.  Other hosts on the switch are not affected.
In this scenario, PortFast protects against mistakes made in the wiring closet or on the off chance that two access ports would become looped under a desk.  (don’t laugh, I’ve seen it happen)
Here’s a partial output from the show spanning-tree command.

Note that Fa0/3’s Role has changed to Back.  This is helpful information as it indicates that two or more ports on the same bridge are connect together.
Fa0/3’s Status has changed to BLK, effectively blocking the loop condition .

The Tech Savvy End-User
Let’s say an end user wants to add a couple of extra network ports to their cubicle.  Instead of calling the help desk and being questioned as to what unauthorized device they are trying to connect to your LAN, they pick up an unmanaged switch from local retailer and connect it to their access port, Fa0/2.  (for the sake of this post let’s assume we’re not MAC locking ports on the switch)

What happens when two ports on the parasite switch connected to access port Fa0/2 become looped?  This partial output from show spanning-tree provides some info.

This should generate a call to the help desk as Fa0/2 immediately transitions to a Blocking state, preventing traffic from the looped parasite switch from entering the network.
Role is indicating Designated (DESG) which means that Fa0/2 is not looped with another port on this switch.  The Type field provides additional information.  Self-looped is a good indicator that something interesting is happening on Fa0/2.  No other hosts on the access switch were impacted.

Conclusions
PortFast is a great feature and can be enabled without compromising loop protection.  You should think twice about ever disabling spanning-tree.  I’ve seen a looped parasite switch bring down a 400 node network where spanning-tree had been disabled or wasn’t available on the particular switches the client has deployed.  Yet another argument for purchasing quality switches for your infrastructure.

2102615    ทฤษฎีสวิตชิงขั้นสูง    Advanced Switching Theory

วงจรโครนัสซีเควนเชียล แผนภาพสเตต ดารางสเตต การหาค่าน้อยที่สุด วงจรซีเควนเชียล ตารางโฟลว์ การกำหนดสถานะ ไซเกิลเรซและอันตราย

(Synchronous sequential circuits; state diagrams; state tables; minimization; incompletely specified sequential circuits; counters and scalers; asynchronous sequential circuits; flow tables, state assignment, cycles and races, and hazards.)

(2102615 จุฬาลงกรณ์มหาวิทยาลัย)

A Cisco switch generates a small amount of network traffic as part of it’s normal housekeeping functions.
It’s important to be able to recognize normal “background noise” when looking at a packet capture.

Below is a packet capture from a Catalyst 3560.  The only device connected to the switch is  an Xp virtual machine running Wireshark.
Note the four types of packets that appear at regular intervals, STP, LOOP, DTP and CDP.  (click on the image for a larger view)

STP
A Spanning Tree Bridge Protocol Data Unit (BPDU) is sent every two seconds as part of the loop detection process.
This particular packet tells us that the root bridge is 00:22:be:21:3e:80, which also happens to be the switch we are connected to.

It is possible to prevent BPDU’s from being sent out an interface by enabling BPDU Filtering .

BPDU Filtering can be enabled globally for every port that has PortFast enabled by using the spanning-tree portfast bpdufilter default command.

Note this also disables loop detection on all access ports,  probably not a good idea under most circumstances.

LOOP
LOOP Reply is a Layer 2 keepalive packet that is sent every ten seconds by default.
The LOOP Reply verifies to IOS that the link is up.  The switch does not actually listen for a reply, it simply verifies that was able to send the packet out the interface.
Loss of three consecutive Layer 2 keepalives will cause the interface to transition to a down state.
It is possible to configure the interval between packets by using the keepalive interface configuration command.

DTP
Dynamic Trunking Protocol (DTP) is a Cisco proprietary protocol used to negotiate a common trunking mode between two switches.
A trunk link differs from an access port in that a trunk can transport more than one VLAN.
DTP packets are sent every thirty seconds by default.
If the switch port is configured as an access port using the switchport mode access command, DTP packets will not be sent from that interface.

When an access port is reconfigured as a trunk port, transmission of DTP packets will resume 30 seconds after the port is reconfigured.

CDP
Cisco Discovery Protocol (CDP) packets are sent every sixty seconds by default.
CDP provides information about the capabilities of a device to it’s connected neighbor.
CDP can be disabled and it’s not a bad idea to do so under certain circumstances especially if security is a concern.

CDP can be disabled globally with the no cdp run command.

CDP can also be disabled on a particular interface with the no cdp enable command.

A mac user goes a week with Windows.  Read more about his experience here.  Its kind of nice how he realizes what is important to him.

I’ve got some serious lust for the new Quad Core 27-inch iMacs, but I get the feeling that the refresh story isn’t quite over yet. Take a look at this product comparison:

Not since the return of Jobs has Apple’s product line-up had overlap like this. The Mac Pro has always been terribly overpriced relative to Apple’s other products but right now it borders on ludicrous. Is Apple going to let this stand until the Mac Pro can be refreshed with Intel’s upcoming “Gulftown” six-core processors next quarter? It doesn’t seem right…

vSwitches are capable of advertising and listening for CDP information from an attached Cisco device.
CDP on a vSwitch is set to “Listen” by default.

To enable CDP you’ll need to access the Service Console.
After logging in type su- to establish root.

First let’s take a look at the command options by using esxcfg-vswitch -h

Use esxcfg-vswitch -l to show a list of configured vSwitches on the host.

Now that we know the vSwitch names, let’s check the CDP status on vSwitch1 using esxcfg-vswitch -b vSwitch1

Set CDP to listen and advertise using the “both” option.  esxcfg-vswitch -B both vSwitch1
Verify the settings using esxcfg-vswitch -b vSwitch1

Executing show CDP neighbors from the Catalyst switch shows the ports that the ESX host resides on and the vmnic of the uplink.

There is an escalating war going on. It started in 2002 with Apple running their now famous Switch advertisements featuring what they call “Real People” who “moved out” of the Windows platform to the Mac. While the switch ad was later replaced by “Get a Mac” in 2006 (and still runs today). In recent years Microsoft has tried a similar tactic but focusing on freedom of choice as its primary value proposition.

I am a Windows user myself both at work and home. I also have a venerable iMAC running OSX 10.4 at home. When I first bought my iMAC I was surprised at how quickly my kids adapted to the new platform even though they bought used Windows PCs at school (they still do). But then again my kids used the iMAC mostly for Net surfing and checking out emails. My wife remains a Windows user although occasionally she powers on the iMAC when she wants a quick check on the web.

I continue to be amazed at the intense Windows versus MAC battles. Apple continues to run these ads enticing people to switch over. But really people, do you honestly think that switching over from XP to Mac OS X just because you hear the horror stories about the early days of Vista is going to be easy. For those who see the hassle of moving from XP to 7 as being difficult, you will face the same hassle of migrating from any Windows platform to Apple Mac.

The reality kicked me very early on when I bought my first Mac. I very quickly realized that I don’t have a plethora of choice in terms of software for the Mac platform. In fact software choice was limited especially during the days of the “G” series processors that powered the Macs of yester-years. Windows emulators back then were notoriously bad. The shift to Intel processors is certainly a welcome boost to most PC users as the Windows software emulators that followed were more stable. The mere presence of Windows emulators suggests that people are not totally out of the Windows world even when they shift to the Mac.

The Windows 7 platform appears (during my tests anyway on a very old – unsupported HP tablet TC1100) stable. It runs most of the XP applications I am familiar with. There is a bit of a learning curve as you learn to grapply with widgets. But the overall experience is pleasant and not as nerve wracking as when I moved to OS X the first time.

I love Apple for continuing to offer OS X upgrades at frequent interval. Likewise I deplore Microsoft’s slow and cumbersome strategy to OS platform upgrades. I can only guess that they are living by the truism “why fix something that ain’t broken?”

Today we live in an “experience” society where product success or failure can be measured by the experience of the individual. Enough individual experience can amass together to destroy (or make it difficult for) a product. The coverse is true. Just look at the mobile platform. For years the dominant OS was Symbian that powered Nokia. Then along came Windows that tried but failed to get sufficient traction because the PC experience is clearly not very conducive for mobile users. When Apple launched the iPhone, users quickly fell in love with the touch experience. Windows has tried to emulate this as it partners with device manufacturers to come up with better user interface but the experience isn’t quite up there as that of the iPhone/iPod Touch.

What I’m getting at here is that anyone who thinks that migrating from Windows XP to Mac OSX is going to be pain free will be in for a rude awakening, particularly for those who are heavy into Windows-based applications. Checkout whether the programs you have been using, and for which you have lots of data resting in archives – say your accounting program or your spreadsheets or your data files. Before you decide to switch to the “cool” MMac factor, find out if there are equivalent programs on the Mac platform that will take your data and allow you to move forward seamlessly. If this is not possible, your choice is clear, stay with Windows. The new Windows 7 platform is an amazing leap forward by Microsoft. I just hope that Microsoft moves a lot faster with its succession of OS updates.

PS: To Microsoft – notice how Apple’s OS is priced way, way cheaper than Microsoft’s? Apple has learned that the fastest way to get into people’s heart is through great experience. The fastest way of shifting hardliners is through their wallets.