On Wednesday, Apr 9, 2003, at 09:51 Canada/Eastern, Peering wrote:
A suggested action could be this: when a prefix is received with a DISCARD
community additive to INTERNET the router should advertise this prefix to
all of its IBGP/EBGP peers. Also, in its forwarding table the next hop for
this route should be pointed to discard bin, for example NULL0 in Cisco.
For DISCARD + NOEXPORT will be advertised to all IBGP peers only.
Although it is not mandatory to set an action with the well known community,
however, not setting an action by default this community may loose its
purpose.
As Network Operators can always manipulate action attributes.
If this was to be generic, well-known behaviour you would want additional semantics for enabling/accepting it, in order to malicious (or accidental) injection of DISCARD-equipped routes from peers. Something like disabling the functionality by default, and requiring explicit configuration to enable it (e.g. per EBGP session, so you could turn it on specifically for customer sessions).
Joe