Subject: WGLC comments on draft-ietf-bfd-vxlan

From: Anoop Ghanwani <[email-masked]>
Date: Thu, 8 Nov 2018 01:58:12 -0800

Here are my comments.

Thanks,
Anoop

==

Philosophical

Since VXLAN is not an IETF standard, should we be defining a standard for
running BFD on it?  Should we define BFD over Geneve instead which is the
official WG selection?  Is that going to be a separate document?

Technical

Section 1:

This part needs to be rewritten:
The individual racks may be part of a different Layer 3 network, or they
could be in a single Layer 2 network. The VXLAN segments/overlays are
overlaid on top of Layer 3 network. A VM can communicate with another VM
only if they are on the same VXLAN segment.
It's hard to parse and, given IRB, the last sentence above is wrong.

Section 3:
 Most deployments will have VMs with only L2 capabilities that
may not support L3.
Are you suggesting most deployments have VMs with no IP
addresses/configuration?

Having a hierarchical OAM model helps localize faults though it requires
additional consideration.
What are the additional considerations?

Would be useful to add a reference to RFC 8293 in case the reader would
like to know more about service nodes.

Section 4
Separate BFD sessions can be established between the VTEPs (IP1 and IP2)
for monitoring each of the VXLAN tunnels (VNI 100 and 200).
IMO, the document should mention that this could lead to scaling issues
given that VTEPs can support well in excess of 4K VNIs.  Additionally, we
should mention that with IRB, a given VNI may not even exist on the
destination VTEP.  Finally, what is the benefit of doing this?  There may
be certain corner cases where it's useful (vs a single BFD session between
the VTEPs for all VNIs) but it would be good to explain what those are.

Sections 5.1 and 6.1

In 5.1 we have
The inner MAC frame carrying the BFD payload has the
following format:
... Source IP: IP address of the originating VTEP. Destination IP: IP
address of the terminating VTEP.

In 6.1 we have

Since multiple BFD sessions may be running between two
VTEPs, there needs to be a mechanism for demultiplexing received BF

packets to the proper session.  The procedure for demultiplexing
packets with Your Discriminator equal to 0 is different from[RFC5880
<https://tools.ietf.org/html/rfc5880>].

*For such packets, the BFD session MUST be identified*

*using the inner headers, i.e., the source IP and the destination IP
present in the IP header carried by the payload of the VXLAN*

*encapsulated packet.*

How does this work if the source IP and dest IP are the same as specified
in 5.1?

Editorial

- Terminology section should be renamed to acronyms.
- Document would benefit from a thorough editorial scrub, but maybe that
will happen once it gets to the RFC editor.

Section 1
"Virtual eXtensible Local Area Network" (VXLAN) [RFC7348
<https://tools.ietf.org/html/rfc7348>]. provides an encapsulation scheme
that allows virtual machines (VMs) to communicate in a data center network.
This is not accurate.  VXLAN allows you to implement an overlay to decouple
the address space of the attached hosts from that of the network.

Section 7

VTEP's -> VTEPs

---

From: Greg Mirsky <[email-masked]>
Date: Fri, 9 Nov 2018 08:50:27 +0700

Hi Anoop,
thank you for your thorough review and the comments. I'm traveling over the
weekend and will respond in details later next week.

Regards,
Greg

On Thu, Nov 8, 2018 at 4:58 PM Anoop Ghanwani <[email-masked]> wrote:

> packets with Your Discriminator equal to 0 is different from[RFC5880 <https://tools.ietf.org/html/rfc5880>].
>
> This is not accurate.  VXLAN allows you to implement an overlay to
> decouple the address space of the attached hosts from that of the network.
>
> Section 7
>
> VTEP's -> VTEPs
>
>

---

From: Greg Mirsky <[email-masked]>
Date: Fri, 9 Nov 2018 08:50:59 +0700

Hi Anoop,
thank you for your thorough review and the comments you've shared. Please
find my answers below tagged GIM>>.

Regards,
Greg

---

From: Greg Mirsky <[email-masked]>
Date: Tue, 13 Nov 2018 11:34:30 -0800

Hi Anoop,
many thanks for the thorough review and detailed comments. Please find my
answers, this time for real, in-line tagged GIM>>.

Regards,
Greg

On Thu, Nov 8, 2018 at 1:58 AM Anoop Ghanwani <[email-masked]> wrote:

> GIM>> IS-IS is not on the Standard track either but that had not prevented
> IETF from developing tens of standard track RFCs using RFC 1142 as the
> normative reference until RFC 7142 re-classified it as historical. A
> similar path was followed with IS-IS-TE by publishing RFC 3784 until it was
> obsoleted by RFC 5305 four years later. I understand that Down Reference,
> i.e., using informational RFC as the normative reference, is not an unusual
> situation.
>

> It's hard to parse and, given IRB,
>
GIM>> Would the following text be acceptable:
OLD TEXT:
   VXLAN is typically deployed in data centers interconnecting
   virtualized hosts, which may be spread across multiple racks.  The
   individual racks may be part of a different Layer 3 network, or they
   could be in a single Layer 2 network.  The VXLAN segments/overlays
   are overlaid on top of Layer 3 network.
NEW TEXT:
VXLAN is typically deployed in data centers interconnecting virtualized
hosts of a tenant. VXLAN addresses requirements of the Layer 2 and
Layer 3 data center network infrastructure in the presence of VMs in
a multi-tenant environment, discussed in section 3 [RFC7348], by
 providing Layer 2 overlay scheme on a Layer 3 network.

 A VM can communicate with another VM only if they are on the same
VXLAN segment.
>
> the last sentence above is wrong.
>
GIM>> Section 4 in RFC 7348 states:
Only VMs within the same VXLAN segment can communicate with each other.

> Are you suggesting most deployments have VMs with no IP
GIM>> Would re-word as follows:
OLD TEXT:
 Most deployments will have VMs with only L2 capabilities that
 may not support L3.
NEW TEXT:
Deployments may have VMs with only L2 capabilities that do not support L3.

> What are the additional considerations?
GIM>> For example, coordination of BFD intervals across the OAM layers.

> like to know more about service nodes.
GIM>> I have to admit that I don't find how RFC 8293  A Framework for
Multicast in Network Virtualization over Layer 3 is related to this
document. Please help with additional reference to the text of the
document.

> the VTEPs for all VNIs) but it would be good to explain what those are.
GIM>> Will add text in the Security Considerations section that VTEPs
should have limit on number of BFD sessions.

> How does this work if the source IP and dest IP are the same as specified
GIM>> You're right, Destination and source IP addresses likely are the same
in this case. Will add that the source UDP port number, along with the pair
of IP addresses, MUST be used to demux received BFD control packets. Would
you agree that will be sufficient?

> - Terminology section should be renamed to acronyms.
GIM>> Accepted

> will happen once it gets to the RFC editor.
GIM>> Will certainly have helpful comments from ADs and RFC editor.

> decouple the address space of the attached hosts from that of the network.
GIM>> Thank you for the suggested text. Will change as follows:
OLD TEXT:
   "Virtual eXtensible Local Area Network" (VXLAN) [RFC7348].  provides
   an encapsulation scheme that allows virtual machines (VMs) to
   communicate in a data center network.
NEW TEXT:
 "Virtual eXtensible Local Area Network" (VXLAN) [RFC7348].  provides
   an encapsulation scheme that allows building an overlay network by
  decoupling the address space of the attached virtual hosts from that of
the network.

> VTEP's -> VTEPs
GIM>> Yes, thank you.

---

From: Anoop Ghanwani <[email-masked]>
Date: Tue, 13 Nov 2018 12:30:27 -0800

Hi Greg,

Please see inline prefixed with [ag].

Thanks,
Anoop

On Tue, Nov 13, 2018 at 11:34 AM Greg Mirsky <[email-masked]> wrote:

>> GIM>> IS-IS is not on the Standard track either but that had not
>> prevented IETF from developing tens of standard track RFCs using RFC 1142
>> as the normative reference until RFC 7142 re-classified it as historical. A
[ag] OK.  I'm not an expert on this part so unless someone else that is an
expert (chairs, AD?) can comment on it, I'll just let it go.

>  providing Layer 2 overlay scheme on a Layer 3 network.

[ag] This is a lot better.

> Only VMs within the same VXLAN segment can communicate with each other.

[ag] VMs on different segments can communicate using routing/IRB, so even
RFC 7348 is wrong.  Perhaps the text should be modified so say -- "In the
absence of a router in the overlay, a VM can communicate...".

> Deployments may have VMs with only L2 capabilities that do not support L3.

[ag] I still don't understand this.  What does it mean for a VM to not
support L3?  No IP address, no default GW, something else?

> GIM>> For example, coordination of BFD intervals across the OAM layers.

[ag] Can we mention them in the draft?

> document. Please help with additional reference to the text of the

[ag] The RFC discusses the use of service nodes which is mentioned here.

> should have limit on number of BFD sessions.

[ag] I was hoping for two things:
- A mention about the scalability issue right where per-VNI BFD is
discussed.  (Not sure why that is a security issue/consideration.)
- What is the benefit of running BFD per VNI between a pair of VTEPs?

> GIM>> You're right, Destination and source IP addresses likely are the
> same in this case. Will add that the source UDP port number, along with the
> pair of IP addresses, MUST be used to demux received BFD control packets.
> Would you agree that will be sufficient?
>

[ag] Yes, I think that should work.

>> Editorial
[ag] Agree with all comments on this section.

---

From: Greg Mirsky <[email-masked]>
Date: Wed, 14 Nov 2018 09:45:19 -0800

Hi Anoop,
thank you for the expedient response. I am glad that some of my responses
have addressed your concerns. Please find followup notes in-line tagged
GIM2>>. I've attached the diff to highlight the updates applied in the
working version. Let me know if these are acceptable changes.

Regards,
Greg

On Tue, Nov 13, 2018 at 12:30 PM Anoop Ghanwani <[email-masked]>
wrote:

>>> Since VXLAN is not an IETF standard, should we be defining a standard
>>> for running BFD on it?  Should we define BFD over Geneve instead which is
>>> the official WG selection?  Is that going to be a separate document?
GIM2>> VM communicates with its VTEP which, in turn, originates VXLAN
tunnel. VM is not required to have IP address as it is VTEP's IP address
that VM's MAC is associated with. As for gateway, RFC 7348 discusses VXLAN
gateway as the device that forwards traffice between VXLAN and non-VXLAN
domains. Considering all that, would the following change be acceptable:
OLD TEXT:
 Most deployments will have VMs with only L2 capabilities that
 may not support L3.
NEW TEXT:
 Most deployments will have VMs with only L2 capabilities and not have an
IP address assigned.

> discussed.  (Not sure why that is a security issue/consideration.)
GIM2>> I've added the following sentense in both places:
The implementation SHOULD have a reasonable upper bound on the number of
BFD sessions that can be created between the same pair of VTEPs.

> - What is the benefit of running BFD per VNI between a pair of VTEPs?
GIM2>> An alternative would be to run CFM between VMs, if there's the need
to monitor liveliness of the particular VM. Again, this is optional.

>>> How does this work if the source IP and dest IP are the same as
>>> specified in 5.1?
>>>
>>> <https://tools.ietf.org/html/rfc7348>]. provides an encapsulation
>>> scheme that allows virtual machines (VMs) to communicate in a data center
>>> network.
>>> >>>

---

From: Anoop Ghanwani <[email-masked]>
Date: Wed, 14 Nov 2018 23:00:37 -0800

Hi Greg,

Please see inline prefixed with [ag2].

Thanks,
Anoop

On Wed, Nov 14, 2018 at 9:45 AM Greg Mirsky <[email-masked]> wrote:

>>> many thanks for the thorough review and detailed comments. Please find
>>> my answers, this time for real, in-line tagged GIM>>.
>>>
>>> Regards,
>>> Greg
>>>
>> [ag] OK.  I'm not an expert on this part so unless someone else that is
>> an expert (chairs, AD?) can comment on it, I'll just let it go.
>>
>>
>>>
>>>
>>>>
>>>> Technical
>>>>
>>>> Section 1:
>>>>
>>>> The individual racks may be part of a different Layer 3 network, or
>>>> they could be in a single Layer 2 network. The VXLAN segments/overlays are

[ag2] Do you have a reference for this (i.e. that most deployments have VMs
without an IP address)?  Normally I would think VMs would have an IP
address.  It's just that they are segregated into segments and, without an
intervening router, they are restricted to communicate only within their
subnet.

>
>>
>>>
>>>> >>>
>>>> Having a hierarchical OAM model helps localize faults though it
>>>> requires additional consideration.
>>>> >>>
>>>> Separate BFD sessions can be established between the VTEPs (IP1 and
>>>> IP2) for monitoring each of the VXLAN tunnels (VNI 100 and 200).
>>>> >>>

[ag2] What is the criteria for determining what is reasonable?

> to monitor liveliness of the particular VM. Again, this is optional.

[ag2] I'm not sure how running per-VNI BFD between the VTEPs allows one to
monitor the liveliness of VMs.

>>>> - Document would benefit from a thorough editorial scrub, but maybe
>>>> that will happen once it gets to the RFC editor.
>>>>
>>>   decoupling the address space of the attached virtual hosts from that
>>> of the network.
>>>
>>>>
>>>> Section 7
>>>>
>>>> VTEP's -> VTEPs
>>>>
>>> GIM>> Yes, thank you.
>>>
>>

---

From: Greg Mirsky <[email-masked]>
Date: Fri, 16 Nov 2018 17:28:55 -0800

Hi Anoop,
thank you for the discussion. Please find my responses tagged GIM3>>. Also,
attached diff and the updated working version of the draft. Hope we're
converging.

Regards,
Greg

On Wed, Nov 14, 2018 at 11:00 PM Anoop Ghanwani <[email-masked]>
wrote:

>>> [ag] VMs on different segments can communicate using routing/IRB, so
>>> even RFC 7348 is wrong.  Perhaps the text should be modified so say -- "In
>>> the absence of a router in the overlay, a VM can communicate...".
>>>
>>>
>>>>
>>>> Section 3:
>>>>> >>>
> [ag2] Do you have a reference for this (i.e. that most deployments have
> VMs without an IP address)?  Normally I would think VMs would have an IP
GIM3>> Would the following text be acceptable:

Deployments might have VMs with only L2 capabilities and not have an IP
address assigned or,
in other cases, VMs are assigned IP address but are restricted to
communicate only within their subnet.

>>>>> Would be useful to add a reference to RFC 8293 in case the reader
>>>>> would like to know more about service nodes.
>>>>>
>>>>> IMO, the document should mention that this could lead to scaling
>>>>> issues given that VTEPs can support well in excess of 4K VNIs.
>>>>> Additionally, we should mention that with IRB, a given VNI may not even
>>>>> exist on the destination VTEP.  Finally, what is the benefit of doing
>>>>> this?  There may be certain corner cases where it's useful (vs a single BFD
>>>>> session between the VTEPs for all VNIs) but it would be good to explain
>>>>> what those are.
>>>>>
GIM>> I usually understand that as requirement to make it controllable,
have configurable limit. Thus it will be up to an network operator to set
the limit.

>> GIM2>> An alternative would be to run CFM between VMs, if there's the
>> need to monitor liveliness of the particular VM. Again, this is optional.
>>
>

---

From: Anoop Ghanwani <[email-masked]>
Date: Tue, 20 Nov 2018 12:14:42 -0800

Hi Greg,

Please see inline prefixed by [ag3].

Thanks,
Anoop

On Fri, Nov 16, 2018 at 5:29 PM Greg Mirsky <[email-masked]> wrote:

> Hi Anoop,
> thank you for the discussion. Please find my responses tagged GIM3>>.
> Also, attached diff and the updated working version of the draft. Hope
> we're converging.
>
> Regards,
> Greg
>
>>> thank you for the expedient response. I am glad that some of my
>>> responses have addressed your concerns. Please find followup notes in-line
>>> tagged GIM2>>. I've attached the diff to highlight the updates applied in
>>> the working version. Let me know if these are acceptable changes.
>>>
>>> Regards,
>>> Greg
>>>
>>>>> virtualized
>>>  Most deployments will have VMs with only L2 capabilities and not have
>>> an IP address assigned.
>>>
>>
[ag3] Yes, this is better.

>> [ag2] I'm not sure how running per-VNI BFD between the VTEPs allows one
>> to monitor the liveliness of VMs.
>>
>
[ag3] I think you missed responding to this.  I'm not sure of the value of
running BFD per VNI between VTEPs.  What am I getting that is not covered
by running a single BFD session with VNI 0 between the VTEPs?

---

From: Greg Mirsky <[email-masked]>
Date: Wed, 21 Nov 2018 16:36:18 -0800

Hi Anoop,
apologies for the miss. Is it the last outstanding? Let's bring it to the
front then.

GIM3>> I've misspoken. Non-zero VNI is recommended to be used to
demultiplex BFD sessions between the same VTEPs. In section 6.1:
   The procedure for demultiplexing
   packets with Your Discriminator equal to 0 is different from
   [RFC5880].  For such packets, the BFD session MUST be identified
   using the inner headers, i.e., the source IP and the destination IP
   present in the IP header carried by the payload of the VXLAN
   encapsulated packet.  The VNI of the packet SHOULD be used to derive
   interface-related information for demultiplexing the packet.

Hope that clarifies the use of non-zero VNI in VXLAN encapsulation of a BFD
control packet.

Regards,
Greg

On Tue, Nov 20, 2018 at 12:14 PM Anoop Ghanwani <[email-masked]>
wrote:

>>>>>> many thanks for the thorough review and detailed comments. Please
>>>>>> find my answers, this time for real, in-line tagged GIM>>.
>>>>>>
>>>>>> Regards,
>>>>>> Greg
>>>>>>
>>>>>>> Since VXLAN is not an IETF standard, should we be defining a
>>>>>>> standard for running BFD on it?  Should we define BFD over Geneve instead
>>>>>>> which is the official WG selection?  Is that going to be a separate
>>>>>>> document?
>>>>> [ag] OK.  I'm not an expert on this part so unless someone else that
>>>>> is an expert (chairs, AD?) can comment on it, I'll just let it go.
>>>>>
>>>>>
>>>>>>
>>>>>>
>>>>>>>
>>>>>>> Technical
>>>>>>>
>>>>>>> Section 1:
>>>>>>>
>>>> The implementation SHOULD have a reasonable upper bound on the number
>>>> of BFD sessions that can be created between the same pair of VTEPs.
>>>>
>>>
>>>>>>> ... Source IP: IP address of the originating VTEP. Destination IP:
>>>>>>> IP address of the terminating VTEP.
>>>>>>> >>>
>>>>>>>
>>>>>>> In 6.1 we have
>>>>>>> >>>
>>>>>>>
>>>>>> GIM>> You're right, Destination and source IP addresses likely are
>>>>>> the same in this case. Will add that the source UDP port number, along with
>>>>>> the pair of IP addresses, MUST be used to demux received BFD control
>>>>>> packets. Would you agree that will be sufficient?
>>>>>>
>>>>>
>>>>>>   decoupling the address space of the attached virtual hosts from
>>>>>> that of the network.
>>>>>>
>>>>>>>
>>>>>>> Section 7
>>>>>>>
>>>>>>> VTEP's -> VTEPs
>>>>>>>
>>>>>> GIM>> Yes, thank you.
>>>>>>
>>>>>

---

From: Anoop Ghanwani <[email-masked]>
Date: Wed, 21 Nov 2018 22:59:56 -0800

Hi Greg,

See below prefixed with [ag4].

Thanks,
Anoop

On Wed, Nov 21, 2018 at 4:36 PM Greg Mirsky <[email-masked]> wrote:

> Hope that clarifies the use of non-zero VNI in VXLAN encapsulation of a
> BFD control packet.
>

[ag4] This tells me how the VNI is used for BFD packets being
sent/received.  What is the use case/benefit of doing that?  I am creating
a special interface with VNI 0 just for BFD.  Why do I now need to run BFD
on any/all of the other VNIs?  As a developer, if I read this spec, should
I be building this capability or not?  Basically what I'm getting at is I
think the draft should recommend using VNI 0.  If there is a convincing use
case for running BFD over other VNIs serviced by that VTEP, then that needs
to be explained.  But as I mentioned before, this leads to scaling issues.
So given the scaling issues, it would be good if an implementation only
needed to worry about sending BFD messages on VNI 0.

>>>>>> [ag] I still don't understand this.  What does it mean for a VM to
>>>>>> not support L3?  No IP address, no default GW, something else?
>>>>>>
>>>>>>> GIM>> I have to admit that I don't find how RFC 8293  A Framework
>>>>>>> for Multicast in Network Virtualization over Layer 3 is related to this
>>>>>>> GIM>> Will add text in the Security Considerations section that
>>>>>>> VTEPs should have limit on number of BFD sessions.
>>>>>>>
>>>>>>
>> [ag3] I think you missed responding to this.  I'm not sure of the value
>> of running BFD per VNI between VTEPs.  What am I getting that is not
>> covered by running a single BFD session with VNI 0 between the VTEPs?
>>
>>
>>>
>>>>
>>>>>
>>>>>>
>>>>>>>
>>>>>>>> Sections 5.1 and 6.1
>>>>>>>>
>>>>>>>> In 5.1 we have
>>>>>>>> >>>

---

From: Greg Mirsky <[email-masked]>
Date: Thu, 22 Nov 2018 12:27:56 -0800

Hi Anoop,
apologies if my explanation was not clear. Non-zero VNIs are recommended to
be used by a VTEP that received BFD control packet with zero Your
Discriminator value. BFD control packets with non-zero Your Discriminator
value will be demultiplexed using only that value. As for the special role
of VNI 0 the section 7 of the draft states the following:
   BFD session MAY be established for the reserved VNI 0.  One way to
   aggregate BFD sessions between VTEP's is to establish a BFD session
   with VNI 0.  A VTEP MAY also use VNI 0 to establish a BFD session
   with a service node.
Would you suggest changing the normative language in this text?

Regards,
Greg

PS. Happy Thanksgiving to All!

On Wed, Nov 21, 2018 at 11:00 PM Anoop Ghanwani <[email-masked]>
wrote:

>>>>>> On Tue, Nov 13, 2018 at 12:30 PM Anoop Ghanwani <
>>>>>> [email-masked]> wrote:
>>>>>>
>>>>>>> Hi Greg,
>>>>>>>
>>>>>>>>> The individual racks may be part of a different Layer 3 network,
>>>>>>>>> or they could be in a single Layer 2 network. The VXLAN segments/overlays
>>>>>>>>> are overlaid on top of Layer 3 network. A VM can communicate with another
>>>>>>>>> VM only if they are on the same VXLAN segment.
>>>>>>>>> >>>
>>>>>>  Most deployments will have VMs with only L2 capabilities and not
>>>>>> have an IP address assigned.
>>>>>>
>>>>>
>>>>> [ag2] Do you have a reference for this (i.e. that most deployments
>>>>> have VMs without an IP address)?  Normally I would think VMs would have an
>>>>> IP address.  It's just that they are segregated into segments and, without
>>>>> an intervening router, they are restricted to communicate only within their
>>>>> subnet.
>>>>>
>>>>>>>>> Separate BFD sessions can be established between the VTEPs (IP1
>>>>>>>>> and IP2) for monitoring each of the VXLAN tunnels (VNI 100 and 200).
>>>>>>>>> >>>
>>>>> [ag2] I'm not sure how running per-VNI BFD between the VTEPs allows
>>>>> one to monitor the liveliness of VMs.
>>>>>
>>>>
>>>>>>>>> - Document would benefit from a thorough editorial scrub, but
>>>>>>>>> maybe that will happen once it gets to the RFC editor.
>>>>>>>>>

---

From: Anoop Ghanwani <[email-masked]>
Date: Fri, 23 Nov 2018 10:47:23 -0800

Hi Greg,

I would recommend the following change.

OLD

7.  Use of reserved VNI

NEW

7.  Use of reserved VNI

   In most cases, only a single BFD session is necessary for a given VTEP
to monitor the reachability to a remote VTEP, regardless of the number of
VNIs in common.  When a single session is used to monitor reachability
remote VTEP, an implementation SHOULD use a VNI of 0.

Thanks,
Anoop

On Thu, Nov 22, 2018 at 12:28 PM Greg Mirsky <[email-masked]> wrote:

> Hi Anoop,
> apologies if my explanation was not clear. Non-zero VNIs are recommended
> to be used by a VTEP that received BFD control packet with zero Your
>>> apologies for the miss. Is it the last outstanding? Let's bring it to
>>> the front then.
>>>

---

From: Greg Mirsky <[email-masked]>
Date: Fri, 23 Nov 2018 13:10:16 -0800

Hi Anoop,
thank you for the consise text. I think I've got the idea. Would the minor
tweak be acceptable?

In most cases, a single BFD session is sufficient for the given VTEP to
monitor
the reachability of a remote VTEP, regardless of the number of VNIs in
common.
When the single BFD session is used to monitor reachability of the remote
VTEP,
an implementation SHOULD use a VNI of 0.

Regards,
Greg

On Fri, Nov 23, 2018 at 10:47 AM Anoop Ghanwani <[email-masked]>
wrote:

>>>>>>> GIM2>> An alternative would be to run CFM between VMs, if there's
>>>>>>> the need to monitor liveliness of the particular VM. Again, this is
>>>>>>> optional.
>>>>>>>
>>>>>>

---

From: Anoop Ghanwani <[email-masked]>
Date: Fri, 23 Nov 2018 14:46:38 -0800

Hi Greg,

That is fine.

Thanks,
Anoop

On Fri, Nov 23, 2018 at 1:10 PM Greg Mirsky <[email-masked]> wrote:

>>>>> [ag3] I think you missed responding to this.  I'm not sure of the
>>>>> value of running BFD per VNI between VTEPs.  What am I getting that is not
>>>>> Hope that clarifies the use of non-zero VNI in VXLAN encapsulation of
>>>>> a BFD control packet.
>>>>>
>>>>

---

From: Greg Mirsky <[email-masked]>
Date: Fri, 23 Nov 2018 16:30:53 -0800

Hi Anoop,
thank you for your comments and the discussion, much appreciated. All that
helped to improve the specification. I've uploaded the -04 version with
updates resulting from your comments and our discussion. Hope I've got them
all right, please let me know. Attached is the diff and the new version of
the draft.

Regards,
Greg

On Fri, Nov 23, 2018 at 2:46 PM Anoop Ghanwani <[email-masked]>
wrote:

>> thank you for the consise text. I think I've got the idea. Would the
>> minor tweak be acceptable?
>>
>>>    In most cases, only a single BFD session is necessary for a given
>>> VTEP to monitor the reachability to a remote VTEP, regardless of the number
>>> of VNIs in common.  When a single session is used to monitor reachability
>>>> apologies if my explanation was not clear. Non-zero VNIs are
>>>> recommended to be used by a VTEP that received BFD control packet with zero
>>>> Your Discriminator value. BFD control packets with non-zero Your
>>>> Discriminator value will be demultiplexed using only that value. As for the
>>>> special role of VNI 0 the section 7 of the draft states the following: