Re-certified CCIE 20572

Finally done with that on last Friday 28th, that test was like a stone over my chest, with all my work and family I had almost no time for studding but I did it anyhow. So now for additional 2 years I can unchange my signature :-). The test was not that hard (ver3) I think the hard was the anticipation for a hard question that will fail me.

DCOF – Data Center of the Future

yesterday we had a virtual event provided by some of the leaders in Data Center Computing (Cisco, VMware, EMC, Oracle, NetApp, APC, EMERSON) the web virtual Event entail some of the challenges and current design's as well as future design and solutions we may encounter in Data Centers.

From my prospective the main event where the 2 first presenters Cisco and VMware, both have joind forces to show you how the Data Center of the Future should look like, VMware as the Application infrastructure and Cisco as the Networking complimentary.

We will expect to see them more and more in Data Centers providing High Availability Fault tolerance and network resilience between Data Centers.

Some of the hot discussed topics where the:

1. VN-link – amazing Cisco Nexus 1000V basically that is a replacement for vSwitch (VMware layer 2 switch on ESX/ESXi) and I will add to it an amazing with huge amount of capabilities in compare to the vSwitch under the ESX/ESXi.
2. FCOE – Fiber Channel Over Ethernet std although not new, in the context of Data Center resiliency, management, scalability and cost reduction FCOE can is defiantly an option.
3. vSphere – VMware Cloud solution version 4, was announced several weeks ago officially by VMware, yesterday was interesting to see the vision for the data center and there honesty about some of their weakness in the networking area (where Cisco compliment them to some level).

I work today a lot with VMware solutions and see their adaptation as their products advanced, the DCOF will be very interesting…

CCIE Re-certification

I have had in the past months much considerations to take before I am starting the process again of studying for my certification, some of the considerations I will share with you (some I will leave to my self). 1) Time - that is the main point as in the last 1.5 years since the CCIE my work had become so hectic and demanding that I barely have time for my family let alone my self. 2) Money - yes you would think becoming a CCIE would win you the jackpot but I would share with you a secret it will not (may be for some lucky ones) the financial crises had got to all. 3) Family - I have 1 wife 1 son and 1 in the oven (we say tphoo tphoo tphoo like touch wood). so I need again to split my self into several pieces hopefully I would be able to reassemble all back (transformers...). 4) Work - Yes work this is the place my pay check come from, again split my self. 5) Should I consider a different track - I gone back and forward on that question over and over. 6) What material to take - again read the same books, rfc's... and if it is a new track where to start. I will not bore you with all the details and I will tell you that the final result was 1) Time = night 2) Money = dont have a choice, my job dose not pay for that but is also fair and not taking my title under her "wings" like I hear about many others. 3) Family = I would just say that I love my wife son and soon to be ... 4) Work = the only once that do not have any considerations. 5) I Decided to re cert in my current track R&S, much less time! 6) Yes no choice but to go back to txt books.

Advice unless you have a spare time or your job help you (time, money, and they need it) do not consider a different track, specialize in your own track be the best you can be where you at.

So Wish me Luck (I will keep my date to my self for now) :-)

TCP Window Scale

One of the overlooked subjects especially when it come to the CCIE RS is the real deep knowledge and understanding of TCP, the one subject from the scope of TCP that I would like to pass to you readers is the concept of Window Scaling. Why do we need window scaling or what the hell is it?! First may be lets start with the why, I do not know about you guys but when I am buying something I expect to utilize it fully and not half way, and the same goes to my Internet line if I buy 10Mbps pipe I do not want to utilize only 5Mbps. So What is Window Scaling and how can he help us better utilize our pipe?! Window Scaling is an optional enhancement that allows us to extend our window size so you say wait why do I need to extend my window size? Well normally the window size is 16 bit with a max size of 64K byte and when you are talking about a in your LAN delay (1ms avg) that is more then enough for just above 500Mbps but when we are over the WAN we start experiencing some delays the amount of throughput we can provide is decreasing fast, already with 10ms delay you can have only just above 5oMbps with 100ms we already in 5Mpbs and you see where is that going. so what and how we can take the 16bit we have in the TCP header and make them bigger well the simple answer is we cant as we have only 16bit not one bit more in the header for window. but what we can do is use the options 3 byte filed to where we indicate what is our scale factor, the defined scale factor can be between 0 to 14 where the max window can be 1GB 65536 * (2^14) = 1073741824 well now we are talking this is a window. but with grate window come grate responsibility, now we need to watch out for overflowing the network causing congestion (the congestion will be for another talk). So basically what we learned is that the higher the Delay we need a bigger window to free the belt on our traffic. The Max Throughput calc is actually very simple: [ WIN(in bits)/delay(in second) ] / 1000000 = Throughput in Mbps Scale Window calc is: (2^scale factore) * window(bytes) Notice that as the WS is optional it must be offered by both sides to and the lowest WS factor win.