Subject: draft-ietf-l2vpn-evpn-03 and MANDATORY A-D routes

From: "Rabadan, Jorge (Jorge)" <[email-masked]>
Date: Mon, 22 Apr 2013 19:25:44 +0000

Hi *,

The draft states that the use of A-D routes per ESI is MANDATORY (section
9.2.1), whereas the use of A-D routes per EVI is OPTIONAL (section 9.4.1).
Draft-sd-l2vpn-overlay-01 states that when NVEs reside on the hypervisor,
there is no need for MH, hence there is no need for A-D routes. I fully
agree with that statement.

Shouldn't we change the use of A-D routes per ESI to OPTIONAL in section
9.2.1 of the base draft?

Thank you.
Jorge

---

From: "Ali Sajassi (sajassi)" <[email-masked]>
Date: Mon, 22 Apr 2013 20:09:42 +0000

Hi Jorge,

Eth A-D route per ESI is used for mass withdraw and that's why it is
mandatory in a multi-homed operation. If the device is single-homed, then
ESI=0 and thus there is no Ether A-D route per ESI.

Cheers,
Ali

---

From: "Rabadan, Jorge (Jorge)" <[email-masked]>
Date: Mon, 22 Apr 2013 20:38:06 +0000

Hi Ali,

Thank you.

OK, my point was that in a network with no multi-homed PEs (some DC
use-cases), the A-D routes are not used at all, hence they are not really
mandatory. 

The MANDATORY statement is within the MH functions section, so I guess I
didn't take that into account when I read "mandatory". Maybe an statement
re-enforcing the fact that they are "mandatory as long as any multi-homing
functions are needed" would help to avoid the confusion?

My other only additional comment is that it would be nice to see in
section 5.1 of the evpn-overlay draft a paragraph explaining that, even
though A-D routes are not required to be generated, they might be required
to be interpreted if there are remote multi-homed NVEs.

Thanks.
Jorge

-----Original Message-----
From: "Ali Sajassi   (sajassi)" <[email-masked]>
Date: Monday, April 22, 2013 1:09 PM
To: Jorge Rabadan <[email-masked]>, "[email-masked]"
<[email-masked]>
Subject: Re: draft-ietf-l2vpn-evpn-03 and MANDATORY A-D routes

---

From: "Ali Sajassi (sajassi)" <[email-masked]>
Date: Mon, 22 Apr 2013 22:18:31 +0000

Hi Jorge,

>functions are needed" would help to avoid the confusion?

O.K. I'll add a sentence to this effect.

>to be interpreted if there are remote multi-homed NVEs.

Yes, Thomas Morin had the same comment at the IETF86. We'll add a
paragraph or so to describe this.

Cheers,
Ali

---

From: Satya Mohanty <[email-masked]>
Date: Tue, 23 Apr 2013 00:53:53 +0000

Hi Jorge/Ali,

I would prefer to retain the status quo i.e. let the per ES AD Route stay as MANDATORY.

It's already stated that a single-homed sites can put the ESI to be 0.
What an implementation may do with this route (if it does not have any multi-homing need) is up to the implementation. 

My point is, whether a given PE implements Multi-homing or not, if it receives the per ES AD route from another PE, it has to treat it accordingly i.e. do the mass withdraw procedures.

Thanks,
--Satya

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of Ali Sajassi (sajassi)
Sent: Monday, April 22, 2013 3:19 PM
To: Rabadan, Jorge (Jorge); [email-masked]
Subject: Re: draft-ietf-l2vpn-evpn-03 and MANDATORY A-D routes

Hi Jorge,

On 4/22/13 1:38 PM, "Rabadan, Jorge (Jorge)"
<[email-masked]> wrote:

>use-cases), the A-D routes are not used at all, hence they are not 
>really mandatory.
>
>The MANDATORY statement is within the MH functions section, so I guess 
>I didn't take that into account when I read "mandatory". Maybe an 
>statement re-enforcing the fact that they are "mandatory as long as any 
>multi-homing functions are needed" would help to avoid the confusion?

>though A-D routes are not required to be generated, they might be 
>required to be interpreted if there are remote multi-homed NVEs.

Yes, Thomas Morin had the same comment at the IETF86. We'll add a paragraph or so to describe this.

Cheers,
Ali

>>>The draft states that the use of A-D routes per ESI is MANDATORY 
>>>(section 9.2.1), whereas the use of A-D routes per EVI is OPTIONAL 
>>>(section 9.4.1).
>>>Draft-sd-l2vpn-overlay-01 states that when NVEs reside on the 
>>>hypervisor, there is no need for MH, hence there is no need for A-D 
>>>routes. I fully agree with that statement.
>>>

---

From: "Rabadan, Jorge (Jorge)" <[email-masked]>
Date: Tue, 23 Apr 2013 02:12:54 +0000

Hi Satya,

I think we are basically saying the same thing. Actually my suggestion was
to add "an statement re-enforcing the fact that A-D routes per ESI are
mandatory as long as any multi-homing functions are needed". Mass withdraw
procedures are indeed part of the multi-homing functions, that must be
followed not only on the multi-homed PEs but also on the remote PEs (even
if they have no ESIs different from zero).

Normally you have EVPN networks with at least one non-reserved ESI, but
when applied to NVO3, we might have EVPNs where all the NVEs reside in
hypervisors, hence no need for A-D per ESI generation/processing.

Thank you.
Jorge

-----Original Message-----
From: Satya Mohanty <[email-masked]>
Date: Monday, April 22, 2013 5:53 PM
To: "Ali Sajassi (sajassi)" <[email-masked]>, Jorge Rabadan
<[email-masked]>, "[email-masked]" <[email-masked]>
Subject: RE: draft-ietf-l2vpn-evpn-03 and MANDATORY A-D routes

>What an implementation may do with this route (if it does not have any
>multi-homing need) is up to the implementation.
>
>My point is, whether a given PE implements Multi-homing or not, if it
>receives the per ES AD route from another PE, it has to treat it
>accordingly i.e. do the mass withdraw procedures.
>
>Thanks,
>--Satya
>
>
>

---

From: John E Drake <[email-masked]>
Date: Tue, 23 Apr 2013 18:36:34 +0000

Hi,

For the per ES and per EVI Ethernet AD route and the Ethernet Segment route, the ESI field must be a globally unique non-zero value.  For the MAC Advertisement route, per section 10.2.2, the ESI field may be zero.

So, a single homed site cannot advertise a per ES Ethernet AD route with an ESI of zero.  It can however advertise a per ES Ethernet AD route with a globally unique non-zero ESI value.  I.e., there is no detectable difference between this case and a multi-homed site with only one active PE. 

Irrespectively Yours,

John

> From: [email-masked] [mailto:[email-masked]] On Behalf
> Of Satya Mohanty
> Sent: Monday, April 22, 2013 5:54 PM
> To: Ali Sajassi (sajassi); Rabadan, Jorge (Jorge); [email-masked]