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Excerpt: The concept of a link-local address is new to some, seeing as the term is not widely talked about in IPv4 circles, despite the fact that some folks see them daily. In IPv4, the range 169.254.1.0 through 169.254.254.255 has been reserved for this purpose. You may see this in the “ipconfig” output of a windows host that failed to pull a DHCP address. In IPv6, fe80::/10 is reserved for this purpose, though link-local addresses are always configured with a fe80::/64 prefix. The concept of a link-local address is much more heavily used in IPv6, and one very popular use case is…
IPv6 Next-Hop Best Practices
March 21, 2013 by 4 Comments
IPv6 Host Networking and Insomnia
March 20, 2013 by Leave a Comment
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Excerpt: I’ve been running IPv6 on my home network for a while. The solution in place has evolved over time, from terminating tunnels to a linux VM using gogo6 all the way to front-ending with a Cisco ISR using Hurricane Electric, the goal has always been the same – to practice what I preach. Running IPv6 at home and *REFUSING* to turn it off when problems arise is one of the best ways to learn the protocol. So after one of the aforementioned evolutions (reconfigurations), I noticed that certain IPv6 web sites were not reachable, while others were. I did basic ping…
Assigning IPv6 Prefixes for Customers
February 25, 2013 by 10 Comments
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Excerpt: Now we arrive at the question of how much address space to allocate for…anyone. You may be a service provider, you may be a business, you may be a home user. Today, this question is quite easy to solve. If you’re a business-class customer, you ask your ISP for a block of addresses, and based off of your need (or ability to justify the need), you’ll be allocated some addresses. For many small-to-medium businesses, this can be as small as 8, or even 4 addresses. Let’s face it – in light of the current availability of globally routable IPv4 addresses,…
A /64 On Every Link? Are You Crazy?
February 25, 2013 by Leave a Comment
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Excerpt: I’ve had some great conversations lately with a lot of folks on the topic of IPv6 prefix length in a variety of applications, specifically one very good discussion on just about anything IPv6 between me, the kind folks over at The Class-C Block and Tom Hollingworth (aka The Networking Nerd). For many folks that are considering the impact of going dual-stack in their environments, the idea of using a /64 on all links is still a point of contention. This becomes a religious debate when this argument is centered around point-to-point (2 host) links. After all – on paper, using a subnet length…
A Cloud Without IPv6
February 14, 2013 by Leave a Comment
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Excerpt: As a Data Center junkie, I daily bear witness to the glorious transformations that are taking place all around me with respect to the “next-generation” of data center. Everyone who wants to move their DC to the next level are millions of dollars worth of DC networking gear that is EXTREMELY cutting edge, enabling virtualization and cloud to do things we only dreamed of being able to do mere years ago. We’re buying enough blade servers to fill hundreds or thousands of racks, counting in the hundreds of petabytes worth of memory, and enough CPU cores to fill a small…
Pinging a Firewall – Is It Up Or Down?
December 18, 2012 by 3 Comments
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Excerpt: Let’s say you’re trying to find a free IP on a network so you can assign one to your PC to do some work. First off, shame on you for not using proper addressing design with an IP address manager software. Second, you might use basic ping tests to properly identify alive hosts vs. dead hosts (free IP addresses). Most do. In fact, you can use nmap to do simple ping sweeps of entire subnets. You see what IPs aren’t responding to pings and there you have it, those IP addresses are free. However – are these IPs truly not in…
Grumpy Cat Hates IPv6
December 2, 2012 by Leave a Comment
IPv6 will ruin the world! What is so terrible now will be a DESOLATE APOCALYPSE WITH IPV6!! BECAUSE…..IT JUST WILL BE – OKAY YOU GUYS???!?!? 
Don’t be grumpy – be happy. NAT is not a device. It is a function. An archaic one that should and can be abandoned, and we don’t have to compromise on security to do it.
