Path MTU discovery (PMTUD) is far from a new concept to IT folk. A sending node sets the Don’t Fragment bit in its IPv4 header which is the nodes way of telling any router along the journey to the packet’s destination that it may not fragment the packet into smaller parts. The router, being an…
I’m setting IPv6 aside for a moment to comment on Ubuntu 12.10. Thanks. Ubuntu 12.10, which is scheduled to be released later this month, is adding a feature that seems to have some fellow ‘nixers up in arms. The Dash search bar which allows you to find pretty much anything on your computer is adding…
Because every interface on your system, physical or virtual, has a link local IPv6 address your system needs a little guidance as to which one to use when sending packets to link-local IPv6 addresses. From an IPv4 perspective this type of addressing is an alien concept. But to IPv6, it’s everyday life.
I can sum it up with one sentence: IPv6 costs money, it does not make it. But the long ago the world received the commandment from the ether: Migrate! Migrate …and pay for it yourself with no immediately obvious capacity for a return on the investment. And we wonder why the migration is almost 20…
I’ll wager that 99% of people who read this from home are coming to me through an IPv4 NAT device that is only a few short steps from where they are sitting. NAT and IPv4, for reasons I understand yet still loathe, just go together these days. I’ll save my un-ending rant against NAT for…
IPv6 has added many new words and ideas to the lexicon of IT professionals. One of the least expected: deprecate. The dictionary (dictionary.com) says that deprecate means “to express earnest disapproval of”, to “urge reasons against” or, oddly, “to pray for deliverance from”. In the IT world the world a thing being ‘deprecated’ is a…
In IPv6 there are four [tables | lists | data structures] used as part of the packet forwarding process (e.g. Neighbor Discovery and the Conceptual Sending Algorithm). They are: Neighbor Cache Destination Cache Prefix List Default Router List These data structures are currently defined by RFC 4861 (and previously by RFC 1970 and RFC 2461,…
Microsoft Windows OS’ have a resolver cache built into the actual OS. Most Windows admins already know this. When your Windows system performs a DNS query the results are stored by the OS and are available for use by other applications and processes running on the system. This means that you can resolve www.itdojo.com to…
I recently read a few articles from around the the Internet regarding the debate surrounding the use of /64 or /126 prefixes on P2P links. Here is a response I left on another site: “The idea of using /126′s is little more than scar tissue from our experience with IPv4. It is the application of…
June 8th, 2011 is World IPv6 Day! If you aren’t already running IPv6 this is as good a time as any to get your systems set up to play on the IPv6 Internet. Head over to the official World IPv6 Day web site and get going. http://worldipv6day.org/