On Sep 30, 2014, at 4:37 PM, Vitkovský Adam <[email protected]> wrote:

> How? 

Any size network can and should perform ingress filtering for 
directly-connecting endpoint networks on its customer edges.  
Customer-of-my-customer (of my customer, of my customer . . .) is problematic.

Egress filtering at peering/upstream transit edges can be problematic, 
depending upon the size of the network in question.  Customer-of-my-customer 
also is problematic.

This is one of the main reasons we don't have universal anti-spoofing - the 
networks which are big enough with enough savvy personnel and automation to do 
it are often topologically unable to do so precisely because of their size and 
downstream wholesalers.

The smaller downstream networks often don't have savvy personnel and/or 
automation sufficient to make it operationally-feasible to do so.  And they 
don't see an economic benefit to doing so (although spoofed traffic costs money 
. . .).

And so it goes . . .

----------------------------------------------------------------------
Roland Dobbins <[email protected]> // <http://www.arbornetworks.com>

                   Equo ne credite, Teucri.

                          -- Laocoön


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