Subject: [Idr] IDR Chairs consensus for draft-ietf-idr-bgp-open-policy

From: Jeffrey Haas <[email-masked]>
Date: Tue, 1 Mar 2022 07:14:06 -0500

Open-Policy Authors,

Thank you for your energetic discussion on the error handling behaviors for
BGP Open-Policy.  The Chairs discussed how we should progress the document
at our meeting today.

While we agree that the error conditions that Bruno had raised are possible
faults for the Open Policy mechanism, RFC 7606 provides clear discussion
about them.  The specific fault under discussion, an OTC Path Attribute with
a length not equal to four, is indeed malformed.

It is our conclusion that the error handling procedures should revert to the
original "treat-as-withdraw" behavior that we started this discussion with.

A key motivation for this conclusion is the need for implementation simplicity.
The discussion highlighted there may be possibility of procedures to handle
the improper size selectively in an iBGP vs. eBGP context. However, attempts
to handle unexpected length errors open us to the possibility of other
buffer data pattern errors wherein malformed data is "successfully" parsed
and must be corrected for.

We'd like to request you to revert your text to treat-as-withdraw.  If you
believe citing the possible dangers of forwarding loops is necessary, please
do so by reference to the text in RFC 7606 without attempts to restate it.
We've found errors tend to creep into specifications when normative text is
summarized.

The Chairs will also discuss whether the concerns raised in this
conversation warrant potential future work on RFC 7606 to provide for safer
methods of error handling in these situations.

Thanks again for your diligence and care for BGP.

-- Jeff (for the Chairs)