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Category: IPv6

Worth Reading: IPv6 Renumbering == Pain in the …

Johannes Weber was forced to stress-test the IPv6 networks are easy to renumber nonsense and documented his test results – a must-read for everyone deploying IPv6.

He found out that renumbering IPv6 in his lab required almost four times as many changes as renumbering (outside) IPv4 in the same lab.

My cynical take on that experience: “Now that you’ve documented everything that needs to be changed, make sure it’s automated the next time ;)

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Happy Eyeballs v2 (and how I Was Wrong Again)

In Moving Complexity to Application Layer I discussed the idea of trying to use all addresses returned in a DNS response when trying to establish a connection with a server, concluding with “I don’t think anyone big enough to influence browser vendors is interested in reinventing this particular wheel.

I’m really glad to report I was wrong ;) This is what RFC 8305 (Happy Eyeballs v2) says:

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Why Can’t We All Use Provider-Independent IPv6 Addresses?

Here’s another back-to-the-fundamentals question I received a while ago when discussing IPv6 multihoming challenges:

I was wondering why enterprise can’t have dedicated block of IPv6 address and ISPs route the traffic to it. Enterprise shall select the ISP's based on the routing and preferences configured?

Let’s try to analyze where the problem might be. First the no-brainers:

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New in IPv6: Stable Random IPv6 Addresses on OpenBSD

The idea of generating random IPv6 addresses (so you cannot be tracked across multiple networks based on your MAC address) that stay stable within each subnet (so you don’t pollute everyone’s ND cache every time you open your iPad) is pretty old: RFC 7217 was published almost exactly four years ago.

Linux was quick to pick it up, OpenBSD got RFC 7127 support a few weeks ago. However, there’s an Easter egg in the OpenBSD patches that implement it: SLAAC on OpenBSD now works with any prefix length (not just /64).

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Meltdown and Its Networking Equivalents

One of my readers sent me this question:

Do you have any thoughts on this meltdown HPTI thing? How does a hardware issue/feature become a software vulnerability? Hasn't there always been an appropriate level of separation between kernel and user space?

There’s always been privilege-level separation between kernel and user space, but not the address space separation - kernel has been permanently mapped into the high-end addresses of user space (but not visible from the user-space code on systems that had decent virtual memory management hardware) since the days of OS/360, CP/M and VAX/VMS (RSX-11M was an exception since it ran on 16-bit CPU architecture and its designers wanted to support programs up to 64K byte in size).

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Unique IPv6 Prefix Per Host – How Complex Do You Want IPv6 to Be?

In December 2017 IETF published RFC 8273 created by the v6ops working group (which means there must have been significant consensus within the working group that we need the solution and that it makes at least marginal sense).

The RFC specifies a mechanism by which the first-hop router allocates a unique /64 IPv6 prefix for every host attached to a subnet and uses unicast and multicast RA responses sent to unicast MAC addresses to give every host the impression that it’s the sole host on its own subnet.

The first thought of anyone even vaguely familiar with how complex IPv6 already is should be “WTF???” Unfortunately, there are good reasons we need this monstrosity.

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RFC8200: IPv6 Is an Internet Standard

You wouldn’t believe it – after almost 22 years (yeah, it’s been that long since RFC 1883 was published), IPv6 became an Internet standard (RFC8200/STD86). No wonder some people claim IETF moves at glacial speed ;)

Speaking of IPv6, IETF and glacial speeds – there’s been a hilarious thread before Prague IETF meeting heatedly arguing whether the default WLAN SSID should be IPv6-only (+NAT64). Definitely worth reading (for the entertainment value) over a beer or two.

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