Hi Robert,
My point is that your proposal to save the 8 bytes of RD can be independent of 
correcting RFC 5449. It is pretty much a no-brainer that revising the 
specification to match the de facto standard of all extant implementations is 
preferable to a non-trivial upgrade and migration.

Anyway, I don’t wish to engage in a protracted debate and I don’t believe the 
WG wishes to delay publication of this draft. Your lone objection can be noted 
in the shepherds report.


From: Robert Raszuk <rob...@raszuk.net>
Date: Monday, December 2, 2019 at 6:37 PM
To: Acee Lindem <a...@cisco.com>
Cc: "slitkows.i...@gmail.com" <slitkows.i...@gmail.com>, "Bocci, Matthew (Nokia 
- GB)" <matthew.bo...@nokia.com>, "bess-cha...@ietf.org" 
<bess-cha...@ietf.org>, "bess@ietf.org" <bess@ietf.org>
Subject: Re: [bess] WG Adoption and IPR Poll for 

Hi Acee,

Please observe that this draft defines encoding for SAFI 129 with IPv6 as next 

If we are prepend it with zero pls do not forget to also submit the errata to 
RFC 6514 which says
clearly in section that next hop *field* must be set to a routable IP 
address. Not part of the
Next Hop field but the entire *field*.

   When re-advertising an Inter-AS I-PMSI A-D route, the ASBR MUST set

   the Next Hop field of the MP_REACH_NLRI attribute to a routable IP

   address of the ASBR.

And the above is just the tip of the iceberg :)

Bottom line is that instead of publishing the spec which in backwards 
compatible fashion allows

gradually to fix the implementation errors of the past it is just blessing 
them. And we all agree

that pushing to each MP_REACH NH field 64 zeros is completely unnecessary. Not 
a good thing

in my measures.



PS. And what happens if those 8 octets is not zeros but zero and ones ? Should 
it be accepted and

ignored or is this an invalid attribute ?

On Mon, Dec 2, 2019 at 11:21 PM Acee Lindem (acee) 
<a...@cisco.com<mailto:a...@cisco.com>> wrote:

What you’re suggesting doesn’t really solve the problem that all the currently 
deployed routers that do not follow RFC 5549. No known implementations follow 
RFC 5549. Were you on the meetecho when this was presented in the BESS meeting 
at IETF 106? There was clear consensus in the meeting.

Anyway,  you can put your ideas in a new draft and let them stand on their own 
merit. That way, if there were consensus, we could save those 8 bytes of RD. 
However, we shouldn’t mix this with the draft revising RFC 5549 to reflect the 
current implementations and deployments.


From: BESS <bess-boun...@ietf.org<mailto:bess-boun...@ietf.org>> on behalf of 
Robert Raszuk <rob...@raszuk.net<mailto:rob...@raszuk.net>>
Date: Thursday, November 28, 2019 at 11:58 AM
To: "slitkows.i...@gmail.com<mailto:slitkows.i...@gmail.com>" 
Cc: "Bocci, Matthew (Nokia - GB)" 
"bess@ietf.org<mailto:bess@ietf.org>" <bess@ietf.org<mailto:bess@ietf.org>>
Subject: Re: [bess] WG Adoption and IPR Poll for 


Adding ability to recognize the length of the next hop to any code is purely 
incremental thing. When vendors were asked I do not even recall if there was a 
question if given implementation can infer next hop format from length or not - 
and that is the key problem/point here.

Just asking if you are prepending zeros or not to NH in some SAFIs and stating 
that if so you do revise 5549 to reflect that is not what we should be doing.

The main reason is that as SAFIs are being defined every now and then and there 
is still no clear document if next hop should match NLRI type or not. Moreover 
4364 is still being developed in few vendors. Sure they want to be backwards 
compatible too, but with that let's also give them a chance to do the right 
thing vs just follow legacy.

So yes if you are opening that box my suggestion is to define an additional 
capability indicating if receiver can process next hop without any additional 
nonsense zero padding. All it takes is one paragraph/section and one IANA 

Stating that this should be new separate document again updating 5549 and now 
5549revised is really not the best option.


On Thu, Nov 28, 2019 at 5:40 PM 
<slitkows.i...@gmail.com<mailto:slitkows.i...@gmail.com>> wrote:
Hi Robert,

Please see some replies inline.


From: Robert Raszuk <rob...@raszuk.net<mailto:rob...@raszuk.net>>
Sent: mercredi 27 novembre 2019 22:18
To: Bocci, Matthew (Nokia - GB) 
Cc: bess@ietf.org<mailto:bess@ietf.org>; 
Subject: Re: [bess] WG Adoption and IPR Poll for 

I do not support this draft in the current form.

This document instead of improving the original specification makes it actually 

Point 1 -

Original RFC sec. 6.2:

   o  Network Address of Next Hop = IPv6 address of Next Hop

Proposed text:

   o  Network Address of Next Hop = VPN-IPv6 address of Next Hop whose
RD is set to zero

As it has been explained when you negotiate in capability AFI2 as next hop it 
is just 16 octets - not 24.
[SLI] AFI2 means that the nexthop is encoded with a format compliant with an 
AFI2, but does not tell anything about the SAFI. A VPN-IPv6 address is still 

Next hop never has an RD.
[SLI] We have already discussed about that. RD doesn’t make any sense for a 
nexthop address. No one disagrees on that point. However our legacy 2547bis 
introduced a nexthop encoded as a VPN-IP address, and all VPN unicast SAFIs are 
following this. As RD does not make sense, zeroes are just added to fit the 
size of the address format. In reality, it is just an IP address with 0es 
padded before. Of course,  it would have been cleaner to use only a regular IP 
address instead of a VPN-IP address but again that’s our legacy.

The fact that some implementations are matching length of NLRI with length of 
next hop no where should be made equal that next hop has 8 octet dummy Route 
[SLI] Again this is coming from legacy.

If revision is to be made would be to explicitly negotiate capability to infer 
next hop encoding from the length.
[SLI] Are you talking about a new capability or the existing ENH cap ? ENH 
tells you what is the NH AFI, so the only length check required is for the case 
of one or two IPv6 addresses. A new cap means a new solution, and that’s not 
the goal here.

Point 2 -

Addition of section 6.3 and SAFI 129 is fine, but again next hop encoding is 
lightly stating suboptimal.


As we have discussed on and off line if revision is to be made let's make it 
both backwards compatible, Let's make it applicable to both IPv4 and IPv6 next 
hop addresses and let's allow explicit capability where implementations could 
indicate that it can recognize next hop value from its length. After all we are 
talking about just 4 discrete possible values here.
[SLI] The goal is not to create something new here, but just to reflect how 
RFC5549 has been implemented for the SAFI 128/129 cases. The goal is also to 
minimize running code changes too (and even avoid !).. We have to deal with 
what has been shipped and deployed by vendors today. We can still create 
something completely new, with a new cap and new procedures, but I think this 
is orthogonal to “aligning RFC5549 with implementations” as RFC5549 is there 
anyway and we can’t blindly forget it due to the codes that are available.


On Wed, Nov 27, 2019 at 1:36 PM Bocci, Matthew (Nokia - GB) 
<matthew.bo...@nokia.com<mailto:matthew.bo...@nokia.com>> wrote:

This email begins a two-weeks WG adoption poll for 
draft-litkowski-bess-rfc5549revision-00 [1] .

Please review the draft and post any comments to the BESS working group list.

We are also polling for knowledge of any undisclosed IPR that applies to this 
Document, to ensure that IPR has been disclosed in compliance with IETF IPR 
rules (see RFCs 3979, 4879, 3669 and 5378 for more details).

If you are listed as an author or a contributor of this document, please 
respond to this email and indicate whether or not you are aware of any relevant 
undisclosed IPR, copying the BESS mailing list. The document won't progress 
without answers from all the authors and contributors.

Currently, there are no IPR disclosures against this document.

If you are not listed as an author or a contributor, then please explicitly 
respond only if you are aware of any IPR that has not yet been disclosed in 
conformance with IETF rules.

This poll for adoption closes on Wednesday 11th December 2019..



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