Subject: [nvo3] Suresh Krishnan's Discuss on draft-ietf-nvo3-arch-07: (with DISCUSS and COMMENT)

From: "Suresh Krishnan" <[email-masked]>
Date: Wed, 14 Sep 2016 21:09:16 -0700

Suresh Krishnan has entered the following ballot position for
draft-ietf-nvo3-arch-07: Discuss

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DISCUSS:
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* Section 3.1.2 : I am trying to understand why a minimum TTL decrement
is expected here. I think the mandated behavior is incorrect and needs to
be fixed. 

   For L3 service, Tenant Systems should expect the IPv4 TTL (Time to
   Live) or IPv6 Hop Limit in the packets they send to be decremented by
   at least 1.

e.g. Consider two IPv6 end systems that are connected using an L3
service. If one of them is the router and another is a host on the same
network a significant part of the Neighbor Discovery functions will stop
working if the hop limit is decremented (from 255 to 254).

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COMMENT:
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* For an architecture based on tunnels I found the lack of discussion
concerning MTUs and fragmentation a bit disconcerting. Has the WG
discussed this?

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From: Alia Atlas <[email-masked]>
Date: Thu, 15 Sep 2016 09:21:41 -0400

Hi Suresh,

> https://datatracker.ietf.org/doc/draft-ietf-nvo3-arch/

The tenant systems are connected across a cloud that is viewed as containing
at least one router in them.  If an L3 service is offered, then the
architecture
expects that the tenant systems are connected to at least one router.    Not
requiring a TTL decrement would make it look like the tenant systems were
connected on the same L2 segment.

The tenant systems are expected to be hosts, not routers.  Does that help?

Yes - standard discussion about understanding the size of the header and
setting the MTU accordingly.  There is also an individual draft talking
about MTU discovery
and how to pass that info on, but not adopted as a  WG item.

---

From: "Black, David" <[email-masked]>
Date: Thu, 15 Sep 2016 13:25:51 +0000

Hi Suresh,

> working if the hop limit is decremented (from 255 to 254).

In that example, the two IPV6 end systems need to be connected by a
virtual link that provides L2 service, e.g. to make ND and ARP work.   Do
you  have suggestions for text to add (and where to add it) that would
make this clearer?

> concerning MTUs and fragmentation a bit disconcerting. Has the WG

Well, IMHO,  observing the intarea WG's level of engagement here, I
don't think more "cooks" are needed on this topic .   It'd be reasonable
to add a sentence on this topic pointing to the intarea tunnels draft.

Thanks, --David

> -----Original Message-----
> From: Suresh Krishnan [mailto:[email-masked]]
> Sent: Thursday, September 15, 2016 12:09 AM
> To: The IESG
> Cc: [email-masked]; Matthew Bocci; [email-masked];
> [email-masked]; [email-masked]
> Subject: Suresh Krishnan's Discuss on draft-ietf-nvo3-arch-07: (with DISCUSS and
> COMMENT)
>

---

From: Suresh Krishnan <[email-masked]>
Date: Thu, 15 Sep 2016 13:49:53 +0000

Hi Alia,

On 09/15/2016 09:21 AM, Alia Atlas wrote:
> Hi Suresh,
>
> On Thu, Sep 15, 2016 at 12:09 AM, Suresh Krishnan
> <[email-masked] <mailto:[email-masked]>> wrote:
>
>     <https://www.ietf.org/iesg/statement/discuss-criteria.html>
>     <https://datatracker.ietf.org/doc/draft-ietf-nvo3-arch/>
>
>
>
> at least one router in them.  If an L3 service is offered, then the architecture

Yes. Absolutely. I did not get that from the description in the draft 
earlier, but that makes sense.

> setting the MTU accordingly.  There is also an individual draft talking about
> MTU discovery

Great.

Thanks
Suresh

---

From: Suresh Krishnan <[email-masked]>
Date: Thu, 15 Sep 2016 13:58:14 +0000

Hi David,

> you  have suggestions for text to add (and where to add it) that would

I do have a suggestion

OLD:
   For L3 service, VNs transport IP datagrams, and a Tenant System is 
provided with a service that only supports IP traffic.

NEW:
   For L3 service, VNs are routed networks that transport IP datagrams, and a 
Tenant System is provided with a service that only supports IP traffic.

> to add a sentence on this topic pointing to the intarea tunnels draft.

:-). Agree with you on the "too many cooks" point. Alia mentioned there is a 
follow up draft in nvo3 that discusses the issues. So I am fine even without 
adding a reference to the tunnels draft.

Thanks
Suresh

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From: Spencer Dawkins at IETF <[email-masked]>
Date: Thu, 15 Sep 2016 09:19:53 -0500

Hi, David and Alia,

> to add a sentence on this topic pointing to the intarea tunnels draft.

Thanks to both of you for helping me understand this better.

Spencer

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From: "Black, David" <[email-masked]>
Date: Thu, 15 Sep 2016 14:26:59 +0000

Hi Suresh,

> Tenant System is provided with a service that only supports IP traffic.

That's completely reasonable and appropriate - will do.

Thanks, --David

> Sent: Thursday, September 15, 2016 9:58 AM
> To: Black, David; The IESG
> Subject: Re: Suresh Krishnan's Discuss on draft-ietf-nvo3-arch-07: (with DISCUSS
> and COMMENT)
> 
> Hi David,
>

---

From: Joe Touch <[email-masked]>
Date: Thu, 15 Sep 2016 08:21:27 -0700

+1 ;-)

MTUs and fragmentation are hard to get right, and even harder to copy
accurately into multiple documents.

Joe (lead author on the intarea tunnels doc)

---

From: Joe Touch <[email-masked]>
Date: Thu, 15 Sep 2016 08:57:05 -0700

Minor suggestion:

Was:

    only supports IP traffic

Should be:

    supports only IP traffic

Joe

On 9/15/2016 7:26 AM, Black, David wrote:
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> nvo3 mailing list
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