BGP Growth projections

Iljitsch van Beijnum iljitsch at
Sun Jul 12 15:41:26 UTC 2009

On 10 jul 2009, at 19:03, Joel Jaeggli wrote:

>> IPv6 is going to explode the routing table in the next 5 years.

> More like, ipv4 is going explode the routing table in the next 5  
> years?

IPv6 is now at something like 1.2 - 1.4 prefixes per AS. So it will  
take a LONG time before we reach 100k v6 prefixes unless something  

IPv4 is already growing very fast, and it's all the small stuff: < / 
16. This is 90% of the allocations and 10% of the address space (from  
memory). This isn't going to be impacted much by the IPv4 depletion.  
There's always people going bankrupt so addresses flow back to the RIRs.

The only way the v4 table is going to explode is if Comcast etc decide  
that rather than 1 /12 they're going to take 4000 /24s or some such.  
Now of course the Comcasts of this world really don't want to spend  
even $1/address, and I think a /24 will be more than $1 after the v4  
space has depleted. But even worse: having 4000 contracts with 4000  
different people with 4000 different lawyers... Suddenly switching to  
IPv6 doesn't seem like such a bad deal anymore.

Bottom line: a router that can do 500k prefixes is probably ok for the  
next 3 years but not likely for the next 5. 750k or more should be  
enough for 5 years, though. And you don't want to buy the router  
you're going to use in 2015 today.

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