maximum ipv4 bgp prefix length of /24 ?

Tue Oct 10 22:51:21 UTC 2023

> 
> The questions you ask Owen are obviously answerable by anyone with access to a BGP routing table dump (which is pretty much anyone!).
> 
> BGP is many things - it is a topology maintenance protocol, but its a traffic engineering protocol and an attack mitigation protocol. In the latter two cases advertising more specifics play a crucial role. The pressure to slice and dice in IPv4 is a mix of reachability in a space where address availability is under acute pressure, and TE and DOS mitigation. The pressures on IPv6 are predominately from the latter two categories. I suspect that as IPv6 becomes a larger part of the traffic mix (and inexorably that appears to be happening) then the TE and DOS issues become more of an operational concern, hence rising more specifics in IPv6. 
> 

I think a certain amount of desegregation for TE is inevitable and will always be part of the system.

At least theoretically, DDOS mitigation specifics should be relatively transient in nature and anti-hijacking more specifics should be solved by RPKI max prefix length attributes in ROAs.

I guess it’s maybe good news that IPv6 rollout is happening faster than RPKI rollout, but IPv6 rollout is still way too slow. There is, however, recent very good news on that front:

owendelong at PK9XYF9GRK-1346 ~ % host www.amazon.com
www.amazon.com is an alias for tp.47cf2c8c9-frontier.amazon.com.
tp.47cf2c8c9-frontier.amazon.com is an alias for d3ag4hukkh62yn.cloudfront.net.
d3ag4hukkh62yn.cloudfront.net has address 108.138.248.64
d3ag4hukkh62yn.cloudfront.net has IPv6 address 2600:9000:24bb:fe00:7:49a5:5fd2:8621
d3ag4hukkh62yn.cloudfront.net has IPv6 address 2600:9000:24bb:2400:7:49a5:5fd2:8621
d3ag4hukkh62yn.cloudfront.net has IPv6 address 2600:9000:24bb:5e00:7:49a5:5fd2:8621
d3ag4hukkh62yn.cloudfront.net has IPv6 address 2600:9000:24bb:7600:7:49a5:5fd2:8621
d3ag4hukkh62yn.cloudfront.net has IPv6 address 2600:9000:24bb:7800:7:49a5:5fd2:8621
d3ag4hukkh62yn.cloudfront.net has IPv6 address 2600:9000:24bb:ae00:7:49a5:5fd2:8621
d3ag4hukkh62yn.cloudfront.net has IPv6 address 2600:9000:24bb:b600:7:49a5:5fd2:8621
d3ag4hukkh62yn.cloudfront.net has IPv6 address 2600:9000:24bb:f000:7:49a5:5fd2:8621

I don’t know how deep into the Amazon process that goes or if it’s possible to actually browse Amazon and complete an order without IPv4 yet, but this is at least significant progress from one of the biggest barriers to IPv6-only that remained a few years ago.

Yes, I could get the answers from my own table dumps, even, but I would have to find/build the necessary analysis tools to crunch the almost 1M prefix tables to extract that information and even beyond that, attempting to infer the cause becomes an even more interesting challenge (as you not only well know, but
have expressed in some of your rather excellent presentations on the subject in past years).

At the moment, the things that pay the bills have higher priorities for my time than delving into these questions that deeply.

Owen

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