smallest globally routed IPv6 subnet
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Hi,
What is the smallest globally routed IPv6 subnet?
I read that /32 is the smallest IPv6 subnet accepted by some filters.
(http://www.space.net/~gert/RIPE/ipv6-filters.html)
Can you give me some hints?
Thank you in advance.
Alex
smallest globally routed IPv6 subnet
If you got allocated a /32, then exactly that /32 is to be routed, nothing more (of course, as you don't have a right to) and nothing less.
/32s that have been allocated are Provider Aggregated (PA) prefixes, as that name implies, they need to be aggregated by the provider.
smallest globally routed IPv6 subnet
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As I understand it, the smallest globally routable entities are: /48
Usually a provider or organisation which handles their own addresses is a Local Internet Registry, which get's it's addresses from a Reginal Internet Registry like RIPE for Europe and a number of other regions. Those addresses are Provider Attached addresses, their is however a different kind, the Provider Independant addresses, which is for larger organisations which need their own addresses but are not a LIR.
If a LIR doesn't need any bigger then /32, it get's assigned a /32, if you are requesting PI, you'll get a /48 if you can't justify that you need any more.
Their are a number of infrastructure type organisations that also get /48, like root- or topleveldomain-nameservers and Internet Exchange Points.
The /48 and bigger come from a different slice of addresses, then the /32 and bigger. To facilitate filtering.
smallest globally routed IPv6 subnet
(Leen: in your text: s/Provider Attached/Provider Aggregated/g which makes quite some difference, especially as the first doesn't exist and otherwise would mean something completely differently)
For PI indeed, one get them in chunks of /48 or larger. PA though comes in /32 or larger. An ISP is supposed to only announce the chunk they are allocated.
Simple example why one should not be announcing smaller chunks out of the space they have been allocated:
Lets say we have an LIR, they receive a /32. Now they want to allocate /48s out of that. This LIR does that, and so do 1000 others. A /32 has 65536 /48s, times 1000 LIRs, which would mean 655.360.000 routes in your routing table. Did you ask your accounting department already how they are going to give more money to Vendor C and J and others? :)
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