Re: [bess] Robert Wilton's Discuss on draft-ietf-bess-evpn-na-flags-06: (with DISCUSS)

["Rob Wilton (rwilton)" <[e-mail]>]

Hi Jorge,

No worries.  Thanks for the update.  Discuss cleared.

Regards,
Rob


From: Rabadan, Jorge (Nokia - US/Mountain View) <[e-mail]>
Sent: 01 December 2020 11:12
To: Rob Wilton (rwilton) <[e-mail]>; The IESG <[e-mail]>
Cc: [e-mail]; [e-mail]; [e-mail]; Bocci, Matthew (Nokia - GB) <[e-mail]>
Subject: Re: Robert Wilton's Discuss on draft-ietf-bess-evpn-na-flags-06: (with DISCUSS)

Rob,

My apologies - I thought I had updated the draft with the agreed text below, but I didn't.
We just published rev 09 which includes the agreed text in the previous emails. Hope it is okay now.

https://tools.ietf.org/rfcdiff?url2=draft-ietf-bess-evpn-na-flags-09.txt

Thank you.
Jorge


From: Rabadan, Jorge (Nokia - US/Mountain View) <[e-mail]<mailto:[e-mail]>>
Date: Monday, October 12, 2020 at 4:48 PM
To: Rob Wilton (rwilton) <[e-mail]<mailto:[e-mail]>>, The IESG <[e-mail]<mailto:[e-mail]>>
Cc: [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>, [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>, [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>, Bocci, Matthew (Nokia - GB) <[e-mail]<mailto:[e-mail]>>
Subject: Re: Robert Wilton's Discuss on draft-ietf-bess-evpn-na-flags-06: (with DISCUSS)
Thank you Rob!
Jorge

From: Rob Wilton (rwilton) <[e-mail]<mailto:[e-mail]>>
Date: Monday, October 12, 2020 at 4:21 PM
To: Rabadan, Jorge (Nokia - US/Mountain View) <[e-mail]<mailto:[e-mail]>>, The IESG <[e-mail]<mailto:[e-mail]>>
Cc: [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>, [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>, [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>, Bocci, Matthew (Nokia - GB) <[e-mail]<mailto:[e-mail]>>
Subject: RE: Robert Wilton's Discuss on draft-ietf-bess-evpn-na-flags-06: (with DISCUSS)
Looks good to me.

Regards,
Rob


From: Rabadan, Jorge (Nokia - US/Mountain View) <[e-mail]<mailto:[e-mail]>>
Sent: 12 October 2020 14:59
To: Rob Wilton (rwilton) <[e-mail]<mailto:[e-mail]>>; The IESG <[e-mail]<mailto:[e-mail]>>
Cc: [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>; Bocci, Matthew (Nokia - GB) <[e-mail]<mailto:[e-mail]>>
Subject: Re: Robert Wilton's Discuss on draft-ietf-bess-evpn-na-flags-06: (with DISCUSS)

Hi Rob,

I think a SHOULD is better - it's good to align implementations, but if one chooses to make a different selection, instead of the latest one, I don't think we can't prevent that. At the end of the day, this is a misconfiguration or a transient condition, so the functionality is not affected either way.

I'll modify it as follows, unless anyone has a strong opinion:

<snip> Receiving multiple EVPN MAC/IP Advertisement routes with I=1 for the same IP but different MAC is considered a misconfiguration or a transient error condition. If this happens in the network, a PE receiving multiple routes (with I=1 for the same IP and a different MAC address) SHOULD update the IP->MAC entry with the latest received information <snip>

Let me know if you are ok with it please.
Thank you!
Jorge

From: Rob Wilton (rwilton) <[e-mail]<mailto:[e-mail]>>
Date: Monday, October 12, 2020 at 3:46 PM
To: Rabadan, Jorge (Nokia - US/Mountain View) <[e-mail]<mailto:[e-mail]>>, The IESG <[e-mail]<mailto:[e-mail]>>
Cc: [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>, [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>, [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>, Bocci, Matthew (Nokia - GB) <[e-mail]<mailto:[e-mail]>>
Subject: RE: Robert Wilton's Discuss on draft-ietf-bess-evpn-na-flags-06: (with DISCUSS)
Hi Jorge,

In-line [RW2].

From: Rabadan, Jorge (Nokia - US/Mountain View) <[e-mail]<mailto:[e-mail]>>
Sent: 12 October 2020 14:31
To: Rob Wilton (rwilton) <[e-mail]<mailto:[e-mail]>>; The IESG <[e-mail]<mailto:[e-mail]>>
Cc: [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>; Bocci, Matthew (Nokia - GB) <[e-mail]<mailto:[e-mail]>>
Subject: Re: Robert Wilton's Discuss on draft-ietf-bess-evpn-na-flags-06: (with DISCUSS)

Hi Rob,

Thank you.
In-line.

From: Rob Wilton (rwilton) <[e-mail]<mailto:[e-mail]>>
Date: Monday, October 12, 2020 at 3:18 PM
To: Rabadan, Jorge (Nokia - US/Mountain View) <[e-mail]<mailto:[e-mail]>>, The IESG <[e-mail]<mailto:[e-mail]>>
Cc: [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>, [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>, [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>, Bocci, Matthew (Nokia - GB) <[e-mail]<mailto:[e-mail]>>
Subject: RE: Robert Wilton's Discuss on draft-ietf-bess-evpn-na-flags-06: (with DISCUSS)
Hi Jorge,

Please see [RW] inline

From: Rabadan, Jorge (Nokia - US/Mountain View) <[e-mail]<mailto:[e-mail]>>
Sent: 09 October 2020 10:30
To: Rob Wilton (rwilton) <[e-mail]<mailto:[e-mail]>>; The IESG <[e-mail]<mailto:[e-mail]>>
Cc: [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>; Bocci, Matthew (Nokia - GB) <[e-mail]<mailto:[e-mail]>>
Subject: Re: Robert Wilton's Discuss on draft-ietf-bess-evpn-na-flags-06: (with DISCUSS)

Hi Robert,

Thank you for the review.
Please see my comments in-line with [jorge].

Jorge

From: Robert Wilton via Datatracker <[e-mail]<mailto:[e-mail]>>
Date: Tuesday, September 22, 2020 at 10:44 PM
To: The IESG <[e-mail]<mailto:[e-mail]>>
Cc: [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>, [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>, [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>, Bocci, Matthew (Nokia - GB) <[e-mail]<mailto:[e-mail]>>, Bocci, Matthew (Nokia - GB) <[e-mail]<mailto:[e-mail]>>
Subject: Robert Wilton's Discuss on draft-ietf-bess-evpn-na-flags-06: (with DISCUSS)
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draft-ietf-bess-evpn-na-flags-06: Discuss

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----------------------------------------------------------------------
DISCUSS:
----------------------------------------------------------------------

Hi,

Hopefully a relatively easy discuss to resolve and this might just be my
ignorance here:

Section 2 states that I flag is used for an immutable ARP/ND Binding which is
for a configured ARP/ND entry.

Section 3.2 Reception of the EVPN ARP/ND Extended Community, has the following
text:

      *  Receiving multiple EVPN MAC/IP Advertisement routes with I=1
         for the same IP but different MAC is considered a
         misconfiguration.

But wouldn't this scenario occur if the configured ARP/ND entry was changed to
point to a new MAC address?
[jorge] well, it shouldn't happen. The old route should be withdrawn before the new one is advertised. I added a sentence in case it helps:
"Receiving multiple EVPN MAC/IP Advertisement routes with I=1 for the same IP but different MAC is considered a misconfiguration. Note that if a configured IP1->MAC1 changes to point to a new MAC address, i.e., IP1->MAC2, the EVPN MAC/IP Advertisement route for IP1->MAC1 will be withdrawn before the EVPN MAC/IP Advertisement route for IP1->MAC2 is advertised."
Would that help?
[RW]
Although I appreciate that the old route should be withdrawn, and hence this shouldn't happen, I'm less convinced that this situation could never occur, and hence I would prefer for the specification to state what the receiver does in this scenario does occur.  I presume that the only safe action would be to update the IP->MAC binding?
Regards,
Rob
[jorge2] sure, still a misconfiguration or a transient condition. Would this address your concern? (see below) If so, I'll add it in the next revision along with other comments from the other reviews:
"Receiving multiple EVPN MAC/IP Advertisement routes with I=1 for the same IP but different MAC is considered a misconfiguration. In case this misconfiguration happens in the network, a PE receiving multiple routes (with I=1 for the same IP and different MAC) will update the IP->MAC entry with the latest received information. Note that if a configured IP1->MAC1 changes to point to a new MAC address, i.e., IP1->MAC2, the EVPN MAC/IP Advertisement route for IP1->MAC1 will be withdrawn before the EVPN MAC/IP Advertisement route for IP1->MAC2 is advertised."
[RW2]
Yes, I think that captures the sentiment.   Possibly, it might help to elaborate on the first sentence, and add RFC2119.  E.g.,
"Receiving multiple EVPN MAC/IP Advertisement routes with I=1 for the same IP but different MAC is considered a misconfiguration or a transient error condition.  If this happens in the network, a PE receiving multiple routes (with I=1 for the same IP and a different MAC address) MUST* update the IP->MAC entry with the latest received information.  Note that if a configured IP1->MAC1 changes to point to a new MAC address, i.e., IP1->MAC2, the EVPN MAC/IP Advertisement route for IP1->MAC1 will be withdrawn before the EVPN MAC/IP Advertisement route for IP1->MAC2 is advertised."
*, I'm not sure whether this is a MUST or a SHOULD.  E.g., if this was a misconfiguration scenario, might the receiver of the message choose to dampen the updates?
Thanks,
Rob



Regards,
Rob