Re: I-D ACTION:draft-rahman-rtg-router-alert-dangerous-00.txt

Hi,

Adding TSVWG and NSIS as "owners" of a protocol using RAO, or that
consider using RAO.

Thanks for producing the draft. I definitely think we need to document
the IETF consensus on this. I don't wish anyone to have to go through
the NSIS debate regarding RAO in the future.

I looked through this draft.
http://www.ietf.org/internet-drafts/draft-rahman-rtg-router-alert-dangerous-00.txt

I reacted on the following sentence from Section 4:

   A router SHOULD inspect Router Alert packets before sending them to
   the "slow path" so that if the protocol to which a packet belongs is
   not enabled on the router or on the incoming interface (physical or
   virtual), then the packet is dropped.

Isn't this preventing use of RAO completely unless all nodes between
source and destination supports RAO and that protocol? Isn't the right
answer to not kick it into the slow path and simply forward it?

To me it seems that this recommendation is death blow to any protocol
already using RAO and completely preventing future use. To me it seems
that the main issue with RAO is how its handling has been implemented.
If one did the filtering of the option in fast path and used the alert
option number to correctly filter for the applications and protocols
present on the node then you would not get such amount of slow path
packets. Then adding filtering behavior to prevent overloading the slow
path and this would work better than the alternative of not using RAO.

I do have to question if you really consider 5 tuple filters pushing
packets into the slow path and then determine if they are a protocol
going to router or not, as a better option? To me it seems to have the
same issues with overload.

And if the document is going to say that no future protocol is going to
use RAO, then please provide a viable alternative that will work better.

Cheers

Magnus Westerlund

IETF Transport Area Director & TSVWG Chair
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