On 03/05/2010 08:39, "Randy Bush" <randy@psg.com> wrote:
I think, in order to come up with a normal figure, we need to normalise the data as best we can. Taking the average number of deaggregates per v4 allocation size should give us an idea of how much people may want to deaggregate their v6 allocation (which in this region is likely to be /32),
Am in full acceptance of the fact that some people deaggregate for either other TE reasons (e.g high localpref and lack of community support by expensive upstream) or no good reason at all (i.e ignorance / assumptions about the way the internet works)
you may find an upcoming JSAC paper somewhat interesting
Interesting paper indeed. To sum this up for people who haven't read, the conclusion states "According to our results, there is no trend towards more aggressive prefix deaggregation or traffic engineering over time", does this mean we shouldn't bother? I did a quick check against the RIPE allocations file for created route objects per allocation which are not the same size (i.e smaller) and summarised based on the CIDR bits of the allocation, here are the results for those that are interested: Bits Average (mean) Deaggs ------------------------ 9: 16 10: 14 11: 24 12: 73 13: 43 14: 31 15: 40 16: 19 17: 19 18: 12 19: 8 <--- Modal average alloc size 20: 6 21: 3 Method was simply to query the database for each allocation and look for smaller routes, take the mean and round down. As you can see, the mean is skewed as the number of bits decreases (and the number of smaller bit allocations is of course reduced due to the number of organisations able to justify that size) The modal average of allocation size is /19 according to the file (followed closely by /20), I guess this tells me that, on average, people are allocated /19s and when they deagg, they create on average 8 deaggregated route objects... (so would likely do so in a uniform fashion with /37s) What it certainly does say is that /36 would be too harsh a limit to impose based on what people appear to be doing now, assuming the deaggs happen as a result of sites (i.e multihoming) Dave.
randy
------------------------------------------------ David Freedman Group Network Engineering Claranet Limited http://www.clara.net