Traceroute and Not-so-Equal ECMP

I came across an odd little issue recently involving equal-cost multipath (ECMP) routing and traceroute. Traceroutes from within our network to destinations out on the Internet were following two different paths, with one path being one hop longer than the other. This resulted in mangled traceroute output, impeding our ability to troubleshoot.

The relevant network topology comprises a mesh of two edge routers and two core switches. Each edge router has a number of transit circuits to different providers, and advertises a default route via OSPF to the two core switches below. The core switches each load-balance traffic across both default routes to either edge routers.

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Because each edge router has different providers, some destinations are routed out via edge1 and others via edge2, which means sometimes a packet will be routed to edge2 via edge1, or vice versa.

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Routers typically employ a hash function using layer three and four information from each packet to pseudo-randomly distribute traffic across equal links. Typically, all packets belonging to a flow (e.g. all packets with the same source and destination IP and port numbers) follow the same path.

However, in this case traceroute packets were being split across two path of unequal Continue reading

In theory…

I don’t normally peruse the reviews of my books — while I appreciate well thought out criticism, I normally find personal notes from folks who’ve read my books more profitable for mining out where I’m falling down on the job as a writer than reviews posted on book seller or book review sites. But one specific book review caught my eye the other day that I think points to a larger issue in the world of engineering, especially network engineering. The reviewer stated, in essence, that there was not enough practical application in my more recent tomes, and that I’m covering the same information over and over again.

Let me begin here — I’m not writing this as a defense of my own writing so much as to think through a habit of mind I think doesn’t really help us as an engineering community.

As far as the facts on the ground go, the reviewer is right on both counts, and wrong on both counts. Let’s imagine, for a moment, that you want to understand how a car works. You approach three different people — one a race car driver, another a top flight mechanic, and another an engineer who Continue reading

Wireshark Certified Network Analyst !!

Well, I finally took the time to buckle down and take the WCNA – Wireshark Certified Network Analyst. Once I finished up with the exam I can happily say I successfully past the exam which I have to admit is pretty cool. Protocol Analysis is definitely an interesting set of technologies to learn & know, it is also […]

WINDOWS IS COMING? WINDOWS IS HERE!

WINDOWS...is_here

Back in June, we told you that Windows was coming. We’ve continued to improve the support, with the help of the outstanding Ansible community, and we’d like to highlight some of the improvements in Ansible 1.9. We now offer additional modules, support for domain authentication, and more.

For more information on Ansible’s Windows support, check out our Windows page, or our Ansible Intro to Windows documentation.

As always, we couldn’t do this without our outstanding Ansible community. Thanks to Chris Church, Jon Hawkesworth, Trond Hindenes, Peter Mounce, Chris Hoffman, Paul Durivage, and more!

The 23 top Apple Watch apps you should get

After a long wait since its introduction last fall -- including eight months and two events -- the Apple Watch is finally reaching customers. Some who managed to order at midnight PT on April 10 are getting their watches now; others who ordered a few minutes later will have to wait until mid-May. That's how quickly the Watch sold out. (I'm somewhere in between; my order went in quickly enough to be in the first batch sold, but I haven't yet received my Watch. At least I can read over the newly posted Apple Watch User Guide while I wait.)+ ALSO: 4 lessons the iPhone should learn from the Apple Watch +To read this article in full or to leave a comment, please click here

Hands on: The first Apple Watch apps for road warriors

Now that the Apple Watch is here, does it do enough useful things to be a standard item for executives, road warriors, and other digital denizens? The Apple Watch's home screen icons can be hard to read, but you can arrange them as you please with the same approach you use on an iPhone's home screen. Yes, you can do useful things on the Apple Watch, but few are that useful. Some are, in fact, downright stupid or useless. In this article, I'll show you which of 30 early Apple Watch apps likely to appeal to business users fall into which category.To read this article in full or to leave a comment, please click here

6 mobile work habits from around the world

Mobile has us working all the time in all kinds of placesImage by ShutterstockThanks to Apple, Samsung, BlackBerry and other mobile movers and shakers, the entire world seems to be on call every waking moment. We're constantly working on our mobile devices, whether in the car, in front of the television, or on the toilet. We're working on vacation and feeling guilty about it. Mobile work has become embedded in every country's culture.To read this article in full or to leave a comment, please click here

Three Areas of Impact on the Networking Industry

The state of the networking industry is undergoing a transformation. Both hardware and software have given way to the realization that applications and infrastructure are less about the individual functions of the sub-components of the overall system and more about the workflows that are being expressed against the technology as a whole.

Workflows, however, are also sub-components of the overall business logic that is being described, and ultimately expressed against the infrastructure. Micro-services and/or services oriented architectures are fundamentally changing many facets of technology, both in business practice and in features and functionality of the technology. They’re enabling a more agile and flexible technological landscape, and are helping to define administrative boundaries with respect to overall operations of the infrastructure.

Impact on Infrastructure

When looking at technology overall there is an obvious pattern emerging in all realms of the hardware that is enabling the industry. Programmability: the desire to express logic against infrastructure much in the same way that we’re able to express logic in the context of an application. “Infrastructure as code” is a phrase I’m sure we’ve all heard over the last couple of years, and this is something that is definitely being attained with the ecosystem of Continue reading

First steps with Python and Junos

I’m just spending the day trying to get my head around some very basic automation, so I thought I would install Python 2.7 and work through some of the tutorials on the Techwiki to see how I get on.

The tutorial I’m following is called Python for Non-Programmers and offers an easy way in for people like me.  Of course as with a lot of open-source stuff, you don’t just download Python and get started – there are various dependencies, and dependencies with dependencies that you need to install first.  If at the end of all that you’ve not forgotten what your name is or why you were doing all this shenanigans in the first place you can count yourself as winning.

Installation on a Windows machine is documented nicely here, but there are a few things which are out of date.

One part where it tells you run an executable to install ‘lxml’ but there isn’t one when you click the link provided.  So instead you need to install it with a program called pip, which can be found in C:Python27scripts by default.  pip is not in the PATH envirronment variable by default Continue reading

Police breaks up cybergang that stole over $15 million from banks

Romanian authorities have detained 25 people who are suspected of being members of an international gang of cyberthieves who hacked into banks, cloned payment cards and used them to steal over US$15 million.The group is believed to have over 52 members of Romanian and other nationalities, and broke into computer systems belonging to banks from Puerto Rico, a U.S. territory, and Muscat, Oman, according to the Romanian Directorate for Investigating Organized Crime and Terrorism (DIICOT).The hackers used the unauthorized access to steal payment card data associated with the accounts of large corporations and then used the data to create fraudulent copies of those cards. The cloned cards were distributed to members of the group who used them to withdraw money from ATMs in different countries, DIICOT said Sunday.To read this article in full or to leave a comment, please click here

The Upload: Your tech news briefing for Monday, April 27

After the earthquake: Tech is a fragile lifeline in NepalIn the first day after a devastating earthquake in Nepal on Saturday, Internet connectivity looked to be an important conduit for bypassing an overloaded telephone network. But by Monday it was clear that large-scale power outages and last-mile Internet connectivity problems were making communications very difficult. The death toll from the quake and numerous aftershocks stands at more than 3,400 people with thousands more injured. Among those killed was a high-ranking Google engineer who was one of a number of expeditioners on Mount Everest who lost their lives in an avalanche triggered by the earthquake.To read this article in full or to leave a comment, please click here

The Upload: Your tech news briefing for Monday, April 27

After the earthquake: Tech is a fragile lifeline in NepalIn the first day after a devastating earthquake in Nepal on Saturday, Internet connectivity looked to be an important conduit for bypassing an overloaded telephone network. But by Monday it was clear that large-scale power outages and last-mile Internet connectivity problems were making communications very difficult. The death toll from the quake and numerous aftershocks stands at more than 3,400 people with thousands more injured. Among those killed was a high-ranking Google engineer who was one of a number of expeditioners on Mount Everest who lost their lives in an avalanche triggered by the earthquake.To read this article in full or to leave a comment, please click here

Alibaba looks to rural China to popularize its mobile OS

E-commerce giant Alibaba Group hasn’t given up on its mobile OS, and is taking the software to China’s rural markets through a series of low-cost phones.The company has partnered with mobile carrier China Telecom to sell the YunOS handsets. The eight phones will be built by lesser-known Chinese brands, and will range from 299 yuan (US$49) to 699 yuan.Although Alibaba has its own Android apps that connect to its popular e-commerce stores, the Linux-based YunOS comes with a whole suite of company-developed services.The software, however, hasn’t gained much share in the market. In 2012, Google claimed it was a variant of its Android OS, sparking a clash that threatened to derail Alibaba’s effort to popularize the mobile OS.To read this article in full or to leave a comment, please click here

A year later, Microsoft’s Nokia deal isn’t a clear winner

It was a marriage of convenience for two industry giants whose past successes weren’t helping them win in the red-hot smartphone market. One year later, it’s hard to say that Microsoft’s acquisition of Nokia’s device business has produced the results its backers envisioned.In the wake of the US$7.2 billion acquisition, Lumia smartphones and the Windows Phone OS are still running into many of the same market roadblocks.But Microsoft isn’t throwing in the towel, and has high hopes that its phone business will get a major boost from Windows 10, which is meant to create an environment where users can move easily between desktops, tablets and their smartphones.To read this article in full or to leave a comment, please click here

A year later, Microsoft’s Nokia deal isn’t a clear winner

It was a marriage of convenience for two industry giants whose past successes weren’t helping them win in the red-hot smartphone market. One year later, it’s hard to say that Microsoft’s acquisition of Nokia’s device business has produced the results its backers envisioned. In the wake of the US$7.2 billion acquisition, Lumia smartphones and the Windows Phone OS are still running into many of the same market roadblocks. But Microsoft isn’t throwing in the towel, and has high hopes that its phone business will get a major boost from Windows 10, which is meant to create an environment where users can move easily between desktops, tablets and their smartphones.To read this article in full or to leave a comment, please click here

Review: MacBook Air killer from ASUS

ZenbookAt first glance, you might mistake the ASUS ZenBook UX305 as a dark-gray edition of the 13-inch MacBook Air. It shares nearly the same design cues and size, but is thinner than the Apple notebook is at its thickest point, and weighs less. It also beats many of the current 13-inch MacBook Air’s hardware specs. And it costs less -- a whole lot less – at $699, compared to $999 for the MacBook Air.To read this article in full or to leave a comment, please click here

Review: MacBook Air killer from ASUS

ZenbookAt first glance, you might mistake the ASUS ZenBook UX305 as a dark-gray edition of the 13-inch MacBook Air. It shares nearly the same design cues and size, but is thinner than the Apple notebook is at its thickest point, and weighs less. It also beats many of the current 13-inch MacBook Air’s hardware specs. And it costs less -- a whole lot less – at $699, compared to $999 for the MacBook Air.To read this article in full or to leave a comment, please click here

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