Re: [Sidrops] Genart last call review of draft-ietf-sidrops-ov-egress-01

[Ben Maddison <[e-mail]>]

On Wed, 2020-03-18 at 12:56 -0700, Randy Bush wrote:
> ( warning: quote depth errors and top posting.  keyur's mta, well
> let's
> not get into that :)
> 
> > Speaking as a wg member.
> 
> and one of the first ROV implementors, tyvm.
> 
> > Shouldn’t you be checking the "my autonomous system number" in the
> > update message (when sending it out to the ebgp peer) as opposed to
> > "my autonomous system number" in the open message.
> > 
> > Regards, Keyur
> > 
> > On 3/17/20, 8:27 PM, "Randy Bush" <[e-mail]> wrote:
> > 
> > > I wanted to avoid "be able to be" and have an explicit actor. I
> > > see
> > > the difficulty you point to below.
> > 
> > i am happy to change to the following
> > 
> > > > As the origin AS may be modified by outbound policy, a BGP
> > > > speaker
> > > > MUST apply ROV policy semantics using the My Autonomous System
> > > > number
> > > > in the BGP OPEN message (see RFC 4271 section 4.2) issued to
> > > > the peer
> > > > to which the UPDATE is being sent.
> > 
> > but, in my free opinion, as it is in IETF LC, the change is enough
> > that
> > it might require approval by chairs and/or AD.
> 
> i think you're right.  what counts for ROV is the origin AS in the
> UPDATE.  open a hole to deviate from that and ...
> 
> and we have to remember that, for these UPDATEs which are
> redistributed
> into BGP by this speaker, have their AS_PATH first created when sent
> to
> the peer.  i.e. we can not (yet) speak of the origin AS in the
> AS_PATH.
> 
> so maybe
> 
>     As the origin AS of a BGP UPDATE is decided by configuration and
>     outbound policy of the BGP speaker, a validating BGP speaker MUST
>     apply Route Origin Validation policy semantics against the origin
>     Autonomous System number which it will put in the AS_PATH (see
> RFC
>     4271 4.3 Path Attributes:b) of the UPDATE to the peer.
> 

Although a little more verbose, perhaps the following is more explicit?

    As the origin AS of a BGP UPDATE is decided by configuration and
    outbound policy of the BGP speaker, a validating BGP speaker MUST
    apply Route Origin Validation policy semantics against the Route
    Origin ASN as determined by applying the procedure in [RFC6811,
    Section 2] to the AS_PATH (see RFC 4271 4.3 Path Attributes:b) that
    it will send in the UPDATE to the peer.

Cheers,

Ben