Luuk,

> On Oct 14, 2025, at 1:50 PM, Luuk Hendriks <[email protected]> wrote:
> It would be useful if a router could provide more detailed, structured
> info on the filtering. The Table Name TLV can be used to annotate things
> on the receiving station, but you can't use it in any logic.
> 
> Can we come up with e.g. a TLV that describes, in some structured way,
> what exactly is filtered out (or the other way around, what is included)
> in the BMP stream for this particular peer?

[and then you illustrate why this is a messy "but..."]

Simple filtering on an AFI/SAFI basis could certainly be represented in a 
simple and standardized basis.  However, that's effectively a form of what 
you'd get in your Peer Up message anyway from the capabilities that are 
exchanged.  

For anything more subtle than this, which is generally a filtered view of a 
given table, it's possibly impractical to signal the policy in question.  In 
some circumstances, it might also be undesirable to make fully visible what is 
- or is not - being filtered.  An example of this might be for security 
purposes.

It's quite likely that filtering is done in a subset of that implementation's 
route policy filtering language.  Such things have been resistant to 
standardization. 

For these reasons, it seems likely that what can be reported on a per-BMP 
session, per-monitored table, from a given monitored entity (what we exchange 
in Peer Up) is a local string that provides at least a summarization of the 
filtering.

I wouldn't discourage the WG from trying to do something better than this.  
However, since anything more clever could go into a different TLV, I wouldn't 
necessarily suggest entwining the progression of something like the original 
proposal to the more clever filter encoding.

-- Jeff

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