BGP Path Attribute Filtering, YES or NO?

Wed Jan 8 12:44:02 UTC 2020

Would like to gather current views of a wider community on BGP Path
Attribute Filtering (discarding selected attributes in particular, not treat
as withdraw) as an addition to the long list of standard conditioning tools
like max as-path length limit, limiting number of communities all the way to
running iBGP infrastructure to carry Internet prefixes separate to the one
carrying customers' L3/L2VPN prefixes. 

And I appreciate the topic is somewhat contentious and there's no simple yes
or no answer either.

My view is that in a stub AS there should be no harm in discarding unused
BGP path attributes,

On transit AS-es I'd expect two opposing views:

One might be: "I have a business to run and don't care about some university
experiments, so unless any of my customers specifically asks for some
attribute I'll drop all reserved, unassigned and deprecated ones and might
even drop some not widely used ones just to be on the well-trodden bug free
path"

Other  might be: "These experimental work is of great value to the community
and there's a process now to announce and manage these experiments, what
about net neutrality, and besides modern BGP implementations should handle
well formatted attributes and if it's not the case its good that these flaws
are being exposed and fixed."

Please let me know your thoughts.

adam  

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