Re: BGP Path Attribute Filtering, YES or NO?

[James Jun <james.jun () towardex com>]

On Wed, Jan 08, 2020 at 03:06:45PM +0200, Mark Tinka wrote:
> From our side, on peering links, re-write all MED to 0 and scrubs all
> communities, and replace them with our own.
>
> On customer links, we re-write MED to 0. 

[ snip ]

I get that you'd want to reset MED on peering sessions, but any particular
rationale on why you'd rewrite MED to 0 on customer sessions?

I would argue that providing the ability for customers to transfer backhaul
costs onto their transit provider is one of the compelling commercial reasons
 *for* IP transit vs. other modes of IP interconnection. 

Conversely speaking, I would also argue that transit provider *should* forward
meaningful MED values on its route advertisements to customers.  If a customer
wants to cold potato his outbound traffic on his own network, that's entirely
his call; he has the option of rewriting MED to 0 if he wants closest exit
to his transit instead.

Most transit providers (at least in US, I can't imagine it's much different
in EU) will permit downstream customers to cold potato traffic through their
network. 

James