FYI:

RouteViews data reveals the following:

- the longest AS path currently seen is 45 hops, 5 "real" hops and 40 prepends
- the longest unprepended path is 14 hops
- 99.95% of prefixes have an AS path are shorter than 20 hops
- if we remove prepends, 99.95% of prefixes have an AS path are shorter than 10 
hops

In theory, if two networks both have 45 hops, that could make the total 90 hops.

Also, if 14 hops all apply a completely reasonable three prepends, that's 56 
hops total.

In practice, if networks make sure to not add additional prepends for paths 
that are already very long, and make sure they're not unusually far from the 
DFZ core of the internet, a 50 hop limit should be safe today.

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