Re: [bess] draft-ietf-bess-evpn-overlay-10 PMSI with Ingress Replication

["Ali Sajassi (sajassi)" <[e-mail]>]

Hi Thomas,

On 12/15/17, 8:42 AM, "BESS on behalf of Thomas Morin" <[e-mail] on behalf of [e-mail]> wrote:

    
    Here I would suggest to authors to consider purely removing this
    paragraph, not because it would be wrong or ambiguous (as said above, I
    don't think it is), but because as far as I can tell it has never meant
    to specify anything not already implied by RFC7432, but was here only
  to help understand.
  
OK, I will remove it in the next rev.
  
Cheers,
Ali
    
    Best,
    
    -Thomas
    
    
    
    
    -----Original Message-----
    > From: John E Drake [mailto:[e-mail]] 
    > Sent: Friday, December 15, 2017 9:52 AM
    > To: EXT - [e-mail] <[e-mail]>; Fedyk,
    > Don <[e-mail]>; Marco Marzetti <[e-mail]>
    > Cc: [e-mail]
    > Subject: RE: [bess] draft-ietf-bess-evpn-overlay-10 PMSI with Ingress
    > Replication
    > 
    > Thomas,
    > 
    > I completely agree w/ your email, below.
    > 
    > Yours Irrespectively,
    > 
    > John
    > 
    > 
    > > -----Original Message-----
    > > From: BESS [mailto:[e-mail]] On Behalf Of Thomas Morin
    > > Sent: Friday, December 15, 2017 5:42 AM
    > > To: Fedyk, Don <[e-mail]>; Marco Marzetti <marco@lamehost.
    > > it>
    > > Cc: [e-mail]
    > > Subject: Re: [bess] draft-ietf-bess-evpn-overlay-10 PMSI with
    > > Ingress 
    > > Replication
    > > 
    > > Hi Don,
    > > 
    > > Fedyk, Don, 2017-12-14 20:33:
    > > > I think the gray area is that this draft talks about BUM traffic
    > > > and 
    > > > ingress replication and then has a section on Multicast tunnels 
    > > > which excludes ingress replication traffic from the tunnels.
    > > 
    > > No, ingress replication is not excluded at all:
    > > 
    > >    The following tunnel types as defined in [RFC6514] can be used
    > > in
    > >    the PMSI tunnel attribute for VXLAN/NVGRE:
    > > 
    > >          + 3 - PIM-SSM Tree
    > >          + 4 - PIM-SM Tree
    > >          + 5 - BIDIR-PIM Tree
    > >          + 6 - Ingress Replication
    > > 
    > > > If you are using point to point VXLAN/NVGRE  tunnels then
    > > > ingress 
    > > > replication is default [...]
    > > 
    > > This formulation surprises me: that some implementations behave as
    > > you 
    > > describe is possibly true (this seems to be the case of the 
    > > implementation that triggered this discussion), but I don't know
    > > about 
    > > any text in the specs we are discussing that would imply such a
    > > 'default'.
    > > 
    > > You might have implementations that in the absence of any local 
    > > configuration for an EVPN instance on which type of tunnel to use
    > > for 
    > > BUM, will default to ingress replication: this is fine, out of the 
    > > scope of what is specified for interop, and not breaking other 
    > > implementations (as long, of course, that what is chosen locally
    > > is 
    > > then advertised as expected in a PMSI Tunnel Attribute).
    > > 
    > > 
    > > > but IMET is being used to identify the NVE IP.    I read RFC7432
    > > > and
    > > > RFC6514 in this area and thought that the PMSI attribute MUST be
    > > > set 
    > > > when there is an Inclusive Multicast Ethernet tag IMET.
    > > 
    > > Yes!  (the text of RFC7432 quoted by Ali reminds us that)
    > > 
    > > 
    > > > I can see two possible fixes:
    > > > -          Specify that the PMSI attribute MUST be set if there
    > > > is an
    > > > IMET route and specify correct attribute.
    > > 
    > > Given the content of RFC7432 and the fact that this is a normative
    > > ref 
    > > of draft-ietf-bess-evpn-overlay, I think that we don't need to
    > > repeat 
    > > this MUST in draft-ietf-bess-evpn-overlay.  That is, unless we 
    > > explicitly identify an ambiguous piece of text.
    > > 
    > > > -          Allow that ingress replication is default when PMSI is
    > > > absent but accept PMSI that specifies ingress replication.
    > > > 
    > > 
    > > I don't think we should do that. It would overnight make non-
    > > compliant 
    > > pre- standard implementation of draft-ietf-bess-evpn-overlay,
    > > without 
    > > a rationale to do so except coping with an implementation that
    > > assumed a bit too much.
    > > 
    > > Best,
    > > 
    > > -Thomas
    > > 
    > > 
    > > 
    > > > From: BESS [mailto:[e-mail]] On Behalf Of Marco 
    > > > Marzetti
    > > > Sent: Thursday, December 14, 2017 9:21 AM
    > > > To: Thomas Morin <[e-mail]>
    > > > Cc: [e-mail]
    > > > Subject: Re: [bess] draft-ietf-bess-evpn-overlay-10 PMSI with 
    > > > Ingress Replication
    > > > 
    > > > Hello,
    > > > 
    > > > I have encountered an implementation that is not attaching any
    > > > PMSI 
    > > > to the IMET.
    > > > The authors think they don't really need it because they only 
    > > > support Ingress Replication.
    > > > Such behavior breaks interoperability with other implementations 
    > > > that are dropping the NLRI if PMSI is not attached.
    > > > 
    > > > So i looked at draft-ietf-bess-evpn-overlay-10 and noticed that 
    > > > there's no clear indication of what the proper behavior is.
    > > > As said i assumed i had to look at RFC7432 and RFC6514 (and i
    > > > did 
    > > > it), but i wasn't 100% sure and i preferred to ask.
    > > > 
    > > > Onestly you already made my day by confirming what i thought.
    > > > My suggestion was to make things more clear, but i admit that it 
    > > > could look redundant.
    > > > 
    > > > Thanks
    > > > 
    > > > 
    > > > 
    > > > 
    > > > 
    > > > 
    > > > 
    > > > On Thu, Dec 14, 2017 at 2:39 PM, Thomas Morin
    > > 
    > > <[e-mail]
    > > > m> wrote:
    > > > > Hi Marco,
    > > > > 
    > > > > Marco Marzetti, 2017-12-14 12:25:
    > > > > > I am writing this email asking you to clarify what's the
    > > > > 
    > > > > suggested
    > > > > > behavior when PMSI Tunnel Type is set to "Ingress
    > > > > > Replication"
    > > > > 
    > > > > (type
    > > > > > 6) as draft-ietf-bess-evpn-overlay-10 only suggests what to
    > > > > > do
    > > > > 
    > > > > with
    > > > > > multicast tunnel trees.
    > > > > > 
    > > > > > I think the originating PE should conform with RFC6514 and
    > > > > 
    > > > > RFC7432
    > > > > > (from which you've taken inspiration) and always (RFC2119
    > > > > > MUST) 
    > > > > > attach PMSI Tunnel attribute with the Tunnel Type set to
    > > > > > Ingress 
    > > > > > Replication and Tunnel Identifier set to a routable address
    > > > > > of
    > > > > 
    > > > > the PE
    > > > > > itself (more specifically NVE's IP address).
    > > > > > 
    > > > > > Is that correct?
    > > > > > In that case i suggest to add the following line at the end
    > > > > > of 
    > > > > > Section 9.
    > > > > > """
    > > > > > For Ingress Replication the PE should follow what's stated in
    > > > > 
    > > > > RFC6514
    > > > > > Section 5 .
    > > > > > """
    > > > > 
    > > > > The text of section 9 lists "Ingress Replication" in the list
    > > > > of 
    > > > > tunnel types that can be used. My understanding is that, in
    > > > > the 
    > > > > absence of anything being specifically said for Ingress 
    > > > > Replication, an implementation should follow what is said in
    > > > > RFC7432 and RFC6514.
    > > > > (What
    > > > > other specs could it follow to implement this supported type ?
    > > > > RFC7432
    > > > > and RFC6514 are more than an inspiration here, these are specs 
    > > > > that the document refers to explicitly)
    > > > > 
    > > > > So I'm not sure that it is useful or needed to add text.
    > > > > 
    > > > > Can you perhaps expand on why the current text would possibly
    > > > > be 
    > > > > ambiguous, misleading or incomplete...?
    > > > > 
    > > > > -Thomas
    > > > > 
    > > > 
    > > > 
    > > > 
    > > > --
    > > > Marco
    > > 
    > > _______________________________________________
    > > BESS mailing list
    > > [e-mail]
    > > https://urldefense.proofpoint.com/v2/url?u=https-
    > > 3A__www.ietf.org_mailman_listinfo_bess&d=DwICAg&c=HAkYuh63rsuhr6Sc
    > > bfh0UjBXeMK-ndb3voDTXcWzoCI&r=CRB2tJiQePk0cT-h5LGhEWH-
    > > s_xXXup3HzvBSMRj5VE&m=tHiUTn9_QXrhs3cw-
    > > Dn9_qwR3VK2xWv72DcpoOfR_SI&s=VxylPoVhzXC58hBsqToxzhUK6-3kfy-
    > > ktUi7A9KZDcs&e=
    
    _______________________________________________
    BESS mailing list
    [e-mail]
    https://www.ietf.org/mailman/listinfo/bess