nested prefixes in Internet

Jon Lewis jlewis at
Mon Nov 21 16:24:20 UTC 2016

On Mon, 21 Nov 2016, Victor Sudakov wrote:

> That's all correct from the point of view of the provider annoncing
> the /19 route, and should be their risk.
> My question was however from a different perspective. If AS333
> receives a /19 from AS111 and a /24 from AS222 (where AS222's /24 is
> nested within AS111's /19), what reason might AS333 have to ignore the /24?
> AS333 is not concerned with possible monetary relations between AS111
> and AS222.

RIB/FIB bloat.  They may figure the least specific route is good enough 
for getting packets to the destination and assume anything more specific 
is just the usual pointless deaggregation so commonly seen on the 
Internet.  Maybe they're putting off hardware upgrades required by a 
current-day unfiltered full table.  Maybe there are features that stop 
working properly on their routers if they load several unfiltered full 
tables into the RIB.

  Jon Lewis, MCP :)           |  I route
                              |  therefore you are
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