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Java is to JavaScript as Car is to Carpet – a Beginner’s Guide

Some recent discussions at work have led me to the surprising realization that lots of people working in IT don't understand that Java and JavaScript are almost completely unrelated to each other. This is actually a fairly important misunderstanding to correct:  it leads to wasted troubleshooting efforts, such as downgrading or upgrading Windows Java installations in response to browser JavaScript errors.

I found the title of this blog entry in a StackOverflow post: "Java is to JavaScript as Car is to Carpet". That's pretty much it, in a nutshell. For the record, the only things that Java and JavaScript have in common are:

1. They are both programming languages.
2. The word "Java".
3. Both came out of the web technology explosion of the early 1990s.
4. Both are frequently encountered in the context of web browsers.

Java is a compiled programming language that was originally developed with a major goal of allowing similar or identical codebases to run on different platforms without needing to be recompiled. It does this by compiling to "bytecode" rather than platform-specific machine code, which then typically runs inside a so-called "Java Virtual Machine". Java was originally developed and controlled by Sun Microsystems (now Oracle), but it has Continue reading

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Back to the Basics…

Now that I’ve finished learning about SDN, and then studied for and passed my latest Cisco certification (CCNA Security, keeping that vendor certification path open!), I’ve gotten into the groove of studying at night (and I as I love IT, and specifically networking, it’s kinda become my hobby… I know, lame, right?) In any case, […]

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The post Back to the Basics… appeared first on Packet Pushers Podcast and was written by Will Dennis.

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Bash and Net-SNMP: a low budget, high frequency SNMP poller

Introduction Note: This assumes you’re on a linux machine, but it should work on any box where you can install and run Bash, for example windows with Cygwin. (You’ll also need the date program from GNU Core Utilities too, but that’s installed by default on any normal Linux or Cygwin system.) Note: For simplicity the […]

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The post Bash and Net-SNMP: a low budget, high frequency SNMP poller appeared first on Packet Pushers Podcast and was written by Nik Weidenbacher.

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Cisco STP forward-time command trick

This is more a topic for exams, like Cisco CCIE, but also it can appear in real-world environments. Consider the following simple topology: SW1 is the spanning-tree root bridge for all VLANs. Imagine that you have a request which ask you that when a port becomes active, no matter of VLAN, it should wait 10 […]

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EtherChannel over 802.1q Tunneling

Consider the following topology: We have one Customer with two distributed locations (SW1, R1 and SW2, R2) connected over Provider backbone. What we want to create is something like this: If Provider support 802.1q and L2 tunneling we can achieve a nice Etherchannel between our 2 remote locations with direct CDP visibility. Also STP and […]

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The Big Bad Internet

I often think there are only two types of stories about the Internet. One is a continuing story of prodigious technology that continues to shrink in physical size and at the same time continue to dazzle and amaze us. We've managed to get the cost and form factor of computers down to that of an ordinary wrist watch, or even into a pair of glasses, and embed rich functionality into almost everything. The other is a darker evolving story of the associated vulnerabilities of this technology, where we've seen "hacking" turn into organised crime and from there into a scale of sophistication that is sometimes termed "cyber warfare". And in this same darker theme one could add the current set of stories about various forms of state sponsored surveillance and espionage on the net. In this article I'd like to wander into this darker side of the Internet and briefly look at some of the current issues in this area of cybercrime, based on some conferences and workshops I've attended recently.

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The bumpy road to E-VPN

In 2004 we were in the planning phase of building a new data center to replace one we had outgrown.   The challenge was to build a network that continued to cater to a diverse range of data center applications and yet deliver significantly improved value.

Each operational domain tends to have one or more optimization problem whose solution is less than optimal for another domain.  In an environment where compute and storage equipment come in varying shapes and capabilities and with varying power and cooling demands, the data center space optimization problem does not line up with the power distribution and cooling problem, the switch and storage utilization problem, or the need to minimize shared risk for an application, to name a few.

The reality of the time was that the application, backed by it's business counterparts, generally had the last word -- good or bad.  If an application group felt they needed a server that was as large as a commercial refrigerator and emitted enough heat to keep a small town warm, that's what they got, if they could produce the dollars for it.  Application software and hardware infrastructure as a whole was the bastard of a hundred independent self-proclaimed Continue reading

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Stateless Routing Through an in-line F5 LTM

When using an F5 load balancer there are 2 predominant ways to setup the network topology. While there are many different names for these methods, in this article I will call them “load balancer on a stick” and in-line. Although the article is about the in-line method, we will quickly review both methods for comparison. […]

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The post Stateless Routing Through an in-line F5 LTM appeared first on Packet Pushers Podcast and was written by Eric Flores.

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Protect, Grow, Transform

It's been a while since I wrote something in this blog. Long holiday season, moving house, multiple projects in neighbor country, were really occupying my time the past several months.

Yesterday I flew 16 hours from Dubai to San Francisco, had to queue 2 hours, and drove about 1 hour to San Jose for some company meeting in Cisco Head Quarter office. Now it's early morning here and I can't really sleep due to 11 hours time zone difference with Dubai, so I guess it's the right time to post new blog.

Last month I was moved to Architecture group for the new Intelligent Infrastructure Center of Excellence team for EMEAR region, focusing on IP NGN and Network Programmability. My current role as Solution Architect is not only to lead complex NGN projects, something that I've been doing for many years, but as well as to grow Cisco Advanced Services business in those focused technologies within the region.

One strategy that we just came up recently is to define the objectives of this new team. We classify the objectives using Protect, Grow, Transform terminology. For example, Protect by focusing on renewal business and ensuring the quality of project delivery, Grow Continue reading

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T-Mobile IPv6 in the US

Swapped from AT&T to T-Mobile in order to take advantage of their 4G/LTE IPv6 network. Since I dogfood IPv6 every chance I get, and the cost to swap saved me a whopping $0.50, I moved forward with it. I find that if I set their EPC.TMOBILE.COM APN to IPv4/IPv6, I don’t really see much in the way of dual-stack actually working on the phone. So I set it from the default IPv4 to just IPv6, and that got it working with native IPv6 and using CLAT+NAT64/DNS64 for IPv4 sites. Screenshot from my Galaxy Nexus running 4.3:

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Packet Design Launches Multicast Explorer for Network Engineers to Conquer the Multicast Routing Frontier

New product expands visibility into complex multicast routing configurations, speeds troubleshooting, and makes planning more accurate 

From market trading data distribution to Internet Protocol television (IPTV) to online education, use of multicast routing is growing but the ability to manage it across networks has been limited. Building on its pioneering work in route analytics, Packet Design has launched Multicast Explorer, an optional module of the company’s flagship Route Explorer system, to provide unprecedented visibility into complex multicast routing configurations. With improved troubleshooting and proactive management – including interactive modeling – network professionals can enhance multicast service quality as well as prevent interruptions and outages. This is particularly important where failures carry severe penalties, such as in the financial services industry. 

Going beyond traditional SNMP and CLI pollers, Multicast Explorer collects and analyzes all IGP routing announcements in real time using a passive technique as well as data collection methods optimized for all major vendor routers. This means the information is always current and accurate for monitoring and troubleshooting multicast issues quickly, preventing the tedious process of querying individual routers and manually correlating the resulting data. If any planned or unplanned configuration changes occur, network managers know immediately Continue reading

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Cisco UCS: Crossing the Streams

Apparently you can cable the A-side Fabric Interconnect to the right IOM in a chassis, and it works just fine. You can even look at the DCE interfaces on a VIC in this chassis and see that the paths have been flipped: This is not true for the “correctly” cabled chassis, where the A-side traces occupy the first two slots: The first two interfaces will always go to the left IOM because the backplane traces are cabled that way.

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Cisco UCS: Crossing the Streams

Apparently you can cable the A-side Fabric Interconnect to the right IOM in a chassis, and it works just fine. You can even look at the DCE interfaces on a VIC in this chassis and see that the paths have been flipped: This is not true for the “correctly” cabled chassis, where the A-side traces occupy the first two slots: The first two interfaces will always go to the left IOM because the backplane traces are cabled that way.

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IPv6 with A10 Load Balancers

So I got to do some honest IPv6 related work at the job the last 2 weeks. One task was to verify we had IPv6 working on the load balancers to hosts behind it. I was a bit wary of the state of IPv6 security on these A10 LBs, so I opted to keep the globally routed IPv6 space on the LB’s uplink interface, and the VIPs. And behind the scenes, use ULA.

Step 1: I generated a /48 of ULA for the location, and assigned a /64 for use on the VLAN that the inside interface of the LB sits on with the servers themselves.

Step 2: Configure ::1/64 on the LB inside vlan interface, and ::2/64 on a server, and verified that they could reach each other.

Step 3: I installed lighttpd on the server and configured it to listen on the ULA address.

Step 4: From my ARIN allocation, I have a /64 reserved for configuring /126s on device links to the router, so I configured it on the LB’s dedicated interface on the router. Using ::1/126 on the router; ::2/126 on the LB’s interface; ::3/126 as the VIP.

Step 5: Create on the LB an “IPv6 Continue reading

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Hot,Cold, Mash Potato Routing and BGP Route Reflector Design Considerations.

If someone tosses you a hot potato, do you want to hold it a long time?  If you like pain maybe the answer is yes – but how many of us like pain?  In the same way, hot potatoes are very applicable to the Service Provider environment. When a service provider receives a packet, if […]

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The post Hot,Cold, Mash Potato Routing and BGP Route Reflector Design Considerations. appeared first on Packet Pushers Podcast and was written by Orhan Ergun.

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MPLS VPNs and Junos config groups: a match made in router heaven

Introduction If you manage MPLS VPNs on Juniper Networks devices running Junos (or are learning about doing so), this tip should make your life easier. I can’t imagine operating MPLS VPNs on a scale of more than a handful of VPNs without it. Below I’ll describe how it works, and then to make sure it’s […]

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The post MPLS VPNs and Junos config groups: a match made in router heaven appeared first on Packet Pushers Podcast and was written by Nik Weidenbacher.

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IPSec Bandwidth Overhead Using AES

Someone asked so lets walk through the overhead introduced when using IPSec with AES; it’s higher than you might think and I haven’t even factored in ISAKMP. Encryption really isn’t ‘my bag’ so if anything is wrong, do let me know; hopefully public scrutiny will mean I can truly rely on these figures. Take a […]

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The post IPSec Bandwidth Overhead Using AES appeared first on Packet Pushers Podcast and was written by Steven Iveson.

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Not-Via? Not-What?

In our last episode (it’s been two weeks!), we talked about P’s and Q’s. Now we’ll get down into a few details, and think through what is probably the simplest mechanism ever designed for finding alternate loop free paths through a two connected network: not-via. Let’s use the embedded network as an example. In this […]

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Show 164 – Cool or Hot? Lapukhov + Nkposong’s BGP SDN

On this Packet Pushers podcast, hosts Ethan Banks and Greg Ferro are joined by Petr Lapukhov for a discussion about his IETF draft on BGP SDN, co-authored with Edet Nkposong. Guests Russ White and Ivan Pepelnjak also join in the discussion, quizzing Petr about the details of the draft and how implementation has worked out thus far […]

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The post Show 164 – Cool or Hot? Lapukhov + Nkposong’s BGP SDN appeared first on Packet Pushers Podcast and was written by Ethan Banks.

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IPv6 multicast over IPv6 IPSec VTI

IPv4 IPSec doesn’t support multicast, we need to use GRE (unicast) to encapsulate multicast traffic and encrypt it. As a consequence, more complication and an additional level of routing, so less performance. One of the advantages of IPv6 is the support of IPSec authentication and encryption (AH, ESP) right in the extension headers, which makes […]