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Sprint's route filters and Europe

  • From: Daniel Karrenberg
  • Date: Tue Jun 04 04:07:22 1996

  > "Alex.Bligh" <[email protected]> writes:
  > Sorry I wasn't clear. If you have a /19 allocated in the RIPE database then
  > for obvious reasons you have to put a /19 route (not a /18) route in the
  > RIPE database. To get ANS to accept this you have to announce a /19 route
  > for this. This got filtered by Sprint.

OK so far.

  > Before Sprint's (much welcomed - thanks Sean) change of heart, you could
  > get around this if you were the lower /19 in the block by also making
  > a /18 advert. As the other half of the /18 was unused normally, this
  > makes no difference to anyone except those in the /19 suddenly get
  > Sprint connectivity. 

Since this means announcing routes to address space not allocated to you
it is dubiuous to say the least.

  > Actually it was likely to be of benefit to
  > any future holder of the upper half of the /18 as that would have
  > been the only way they would have gained Sprint connectivity (effectively
  > the holder of the lower half gives them partial transit to the point
  > where the upper /19 advert hits the /18 route to Sprint). This possibly
  > slightly naughty but oh-so-tempting hack would have meant that European
  > local IRs were likely to announce a /18 and a lower /19, and an upper
  > /19 rather than just two /19s. So Sprint would see one /18 and get
  > suboptimal routing, everyone else would see 3 adverts rather than 2.
  > 
  > Hope that makes sense.

Technically I understand what you are saying. 
Whether "it makes sense" is another matter.

  > Anyway, all sorted out now Sprint have changed their policy. Glad
  > the world has seen sense (i.e. RIPE and Sprint have agreed on the
  > same size - whether it was /18 or /19 didn't matter to me, just
  > as long as it was consistent).

Yes indeed.

Daniel
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