an effect of ignoring BCP38

Pekka Savola pekkas at
Thu Sep 11 08:32:57 CDT 2008

On Thu, 11 Sep 2008, Jo Rhett wrote:
>> [Pekka:]
>> Loose mode URPF is [..] (IMHO) pretty much waste of time and is confusing 
>> the discussion about real spoofing protection.  The added protection 
>> compared to ACLs that drop private and possibly bogons is not that big and 
>> it causes transient losses when the routing tables are changing.
> I disagree.   But I will say that if everyone would apply strict mode or ACLs 
> to their end point interfaces, this would likely make most of the loose mode 
> irrelevant.

FWIW, based on off-list discussion, Jo's disagreement seems to stem 
from a misunderstanding of how loose uRPF works (he didn't know it 
accepts any packet that has a route in the routing table).

Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings

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