Re: BFD over VXLAN: Trapping BFD Control packet at VTEP

Greg Mirsky <gregimirsky@gmail.com> Mon, 05 August 2019 22:04 UTC

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From: Greg Mirsky <gregimirsky@gmail.com>
Date: Mon, 5 Aug 2019 15:04:34 -0700
Message-ID: <CA+RyBmW38DY2xaebViT3goj=g3bHY5QrR7ttvKxyB=JmfYW0qg@mail.gmail.com>
Subject: Re: BFD over VXLAN: Trapping BFD Control packet at VTEP
To: Dinesh Dutt <didutt@gmail.com>
Cc: "Joel M. Halpern" <jmh@joelhalpern.com>, Santosh P K <santosh.pallagatti@gmail.com>, rtg-bfd WG <rtg-bfd@ietf.org>, "T. Sridhar" <tsridhar@vmware.com>, bfd-chairs@ietf.org, Martin Vigoureux <martin.vigoureux@nokia.com>, draft-ietf-bfd-vxlan@ietf.org
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Hi Dinesh,
what do you see as the way forward? I agree, that the proposed text doesn't
work for multi-VNI concurrent monitoring because these VNIs are tenant's
VNIs. And in that case, we need to specify another mechanism to trap the
BFD Control packet at VTEP. It seems that VTEP's Ethernet address must be
used as the destination MAC address in the inner Ethernet frame. The
destination IP address may be either VTEP's address of martian (I do prefer
martian). Let me give it  try:
NEW TEXT:

To monitor continuity of the path between two VTEPs, an operator MUST
select a VNI number to be used as Management VNI. Management VNI number
MUST NOT be one of the tenant's VNIs to prevent sending VXLAN packets
received on Management VNI to a tenant. VNI number 1 is RECOMMENDED as the
default for Management VNI. [Ed.note: What we set the Destination MAC to?
Can it be invalid MAC that MUST be ignored on receipt?]

If an implementation supports concurrent monitoring of multiple VNIs, then
the value of VNI number MAY be one of tenant's VNIs. The destination MAC
address in the inner Ethernet frame encapsulating BFD Control packet MUST
be MAC associated with the remote VTEP.
The destination IP address of the inner IP packet MUST be selected from the
range 127/8 for IPv4, and for IPv6 from the range
0:0:0:0:0:FFFF:7F00:0/104. The TTL value in the inner IP header MUST be set
to 1.

Regards,
Greg

On Sun, Aug 4, 2019 at 9:07 AM Dinesh Dutt <didutt@gmail.com> wrote:

> Hi Greg,
>
> Thanks for your clarifications. I agree with your sentiment on why you're
> running BFD over VXLAN between VTEPs. I wasn't arguing against it at all.
> All I was saying was pointing to the limitations of the use of management
> VNI. I spoke to some operators who're running EVPN and mentioned the
> discussion on this thread. They concur that they're using specific VNIs to
> test connectivity over that VNI between VTEPs to ensure misconfiguration
> doesn't lead to blackholes. My statements are based in real world operator
> experience. And I was providing language that ensured packets didn't leak
> across to tenants when they were destined to VTEPs.
>
> Dinesh
>
> On Sat, Aug 3, 2019 at 10:34 AM Greg Mirsky <gregimirsky@gmail.com> wrote:
>
>> Hi Dinesh,
>> many thanks for your detailed updates on how some implementations process
>> VXLAN header and the inner Ethernet frame. These are very helpful in
>> achieving the workable solution for the problem at hand.
>> You've noted that a path between VTEPs may be monitored in the underlay
>> network by merely establishing a BFD session. That is true, but by using
>> BFD with VXLAN encapsulation between the pair of VTEPs we are extending the
>> OAM domain by including, to some extent, VXLAN forwarding engine. Abstract
>> in RFC 5880 defines the goal and the domain in which BFD protocol can
>> detect a fault as:
>>    This document describes a protocol intended to detect faults in the
>>    bidirectional path between two forwarding engines, including
>>    interfaces, data link(s), and to the extent possible the forwarding
>>    engines themselves, with potentially very low latency.
>> Thus, BFD in the underlay will exercise a part of IP forwarding engine
>> while BFD with VXLAN encapsulation, ran between the same pair of VTEPs,
>> extends the OAM domain. At the same time, defining BFD between tenant
>> systems in outside the goal of this specification. But VXLAN BFD session
>> between VTEPs may be useful in monitoring e2e path between tenants, as
>> described in the update to -07:
>>    At the same time, a service layer BFD session may be used between the
>>    tenants of VTEPs IP1 and IP2 to provide end-to-end fault management.
>>    In such case, for VTEPs BFD control packets of that session are
>>    indistinguishable from data packets.  If end-to-end defect detection
>>    is realized as the set of concatenated OAM domains, e.g., VM1-1 - IP1
>>    -- IP2 - VM2-1, then the BFD session over VXLAN between VTEPs SHOULD
>>    follow the procedures described in Section 6.8.17 [RFC5880].
>> I've attached the current working version of the draft.
>>
>> Regards,
>> Greg
>>
>>
>> On Fri, Aug 2, 2019 at 5:43 PM Dinesh Dutt <didutt@gmail.com> wrote:
>>
>>> What I mean is "How do you infer that it excludes the case I'm talking
>>> about?".
>>>
>>> Dinesh
>>>
>>> On Fri, Aug 2, 2019 at 5:41 PM Dinesh Dutt <didutt@gmail.com> wrote:
>>>
>>>> The abstract reads this: "
>>>>
>>>> This document describes the use of the Bidirectional Forwarding
>>>>    Detection (BFD) protocol in point-to-point Virtual eXtensible Local
>>>>    Area Network (VXLAN) tunnels forming up an overlay network."
>>>>
>>>> How do you infer what you said?
>>>>
>>>> Dinesh
>>>>
>>>>
>>>> On Fri, Aug 2, 2019 at 5:38 PM Joel M. Halpern <jmh@joelhalpern.com>
>>>> wrote:
>>>>
>>>>> I am going by what the draft says its purpose is.  If you (Dinesh)
>>>>> want
>>>>> the draft to fulfill a different purpose, then either ask the chairs
>>>>> to
>>>>> take this draft back to the WG, or write a separate draft.
>>>>> As currently written, the behavior Greg proposed meets the needs, and
>>>>> does so in a way that is consistent with VxLAN.
>>>>>
>>>>> Yours,
>>>>> Joel
>>>>>
>>>>> On 8/2/2019 8:30 PM, Dinesh Dutt wrote:
>>>>> > What is the stated purpose of this BFD session? The VTEP
>>>>> reachability is
>>>>> > determined by the underlay, I don't need VXLAN-encaped packet for
>>>>> that.
>>>>> > Do we agree?
>>>>> >
>>>>> > If I want to test the VXLAN encap/decap functionality alone, picking
>>>>> any
>>>>> > single VNI maybe fine. But is this all any network operator wants?
>>>>> Why?
>>>>> > In what situations has this been a problem? I suspect operators also
>>>>> > want to verify path continuity over a specific VNI. If you say this
>>>>> is
>>>>> > not defined by the document, I disagree because the current version
>>>>> > talks about controlling the number of BFD sessions between the VTEPs
>>>>> > (see section 3). More importantly, this is a real problem that
>>>>> operators
>>>>> > like to verify.
>>>>> >
>>>>> > Dinesh
>>>>> >
>>>>> > On Fri, Aug 2, 2019 at 5:08 PM Joel M. Halpern <jmh@joelhalpern.com
>>>>> > <mailto:jmh@joelhalpern.com>> wrote:
>>>>> >
>>>>> >     What is special about the management VNI is precisely that it is
>>>>> NOT a
>>>>> >     tenant VNI.  The VxLAN administration does know how it allocates
>>>>> VNI to
>>>>> >     tenants, and which VNI it has allocated.  In contrast, it does
>>>>> not know
>>>>> >     which IP addresses or MAC adddresses teh tenant is using or may
>>>>> plan
>>>>> >     to use.
>>>>> >
>>>>> >     Yours,
>>>>> >     Joel
>>>>> >
>>>>> >     On 8/2/2019 6:41 PM, Dinesh Dutt wrote:
>>>>> >      > The assumption of an IP address within any VNI is suspect
>>>>> that way.
>>>>> >      > What's special about a single VNI, the management VNI? The
>>>>> VTEP IP
>>>>> >      > address does not belong in reality in any VNI.
>>>>> >      >
>>>>> >      > Dinesh
>>>>> >      >
>>>>> >      > On Fri, Aug 2, 2019 at 3:17 PM Joel M. Halpern
>>>>> >     <jmh@joelhalpern.com <mailto:jmh@joelhalpern.com>
>>>>> >      > <mailto:jmh@joelhalpern.com <mailto:jmh@joelhalpern.com>>>
>>>>> wrote:
>>>>> >      >
>>>>> >      >     Your response seems to miss two points:
>>>>> >      >
>>>>> >      >     First, the problem you describe is not what the document
>>>>> says
>>>>> >     it is
>>>>> >      >     solving.  To the degree it discusses it at all, the
>>>>> document
>>>>> >     says "
>>>>> >      >       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. "
>>>>> >      >
>>>>> >      >     Second, you assume the existence of an IP address for a
>>>>> VTEP
>>>>> >     within a
>>>>> >      >     VNI.  As with the MAC address, the VTEP does not have an
>>>>> IP
>>>>> >     address
>>>>> >      >     within the VNI.  Some implementations may have created
>>>>> such a
>>>>> >     thing,
>>>>> >      >     but
>>>>> >      >     the general construct, as defined to date, does not
>>>>> support such.
>>>>> >      >
>>>>> >      >     In short, you are requiring a behavior that violates the
>>>>> >     architectural
>>>>> >      >     structure of overlay / underlay separation, and common
>>>>> >     usage.  And you
>>>>> >      >     are doing so to support a use case that the working group
>>>>> has not
>>>>> >      >     indicated in the document as important.
>>>>> >      >
>>>>> >      >     Yours,
>>>>> >      >     Joel
>>>>> >      >
>>>>> >      >     On 8/2/2019 5:01 PM, Dinesh Dutt wrote:
>>>>> >      >      > Joel,
>>>>> >      >      >
>>>>> >      >      > You understood correctly.
>>>>> >      >      >
>>>>> >      >      > The VNIs may not share fate due to misconfiguration.
>>>>> And I
>>>>> >     strongly
>>>>> >      >      > suspect someone will want to use BFD for that because
>>>>> its
>>>>> >     about
>>>>> >      >     checking
>>>>> >      >      > path continuity as stated by the draft. As long as
>>>>> there's a
>>>>> >      >     valid IP
>>>>> >      >      > (because it's BFD) owned by the VTEP in that VNI, you
>>>>> can
>>>>> >     use BFD in
>>>>> >      >      > that VNI. Thats all that you need to dictate.  That IP
>>>>> address
>>>>> >      >     has a MAC
>>>>> >      >      > address and you can use that on the inner frame. That
>>>>> is
>>>>> >     all normal
>>>>> >      >      > VXLAN processing. The outer IP is always that of the
>>>>> VTEP.
>>>>> >      >      >
>>>>> >      >      > Dinesh
>>>>> >      >      >
>>>>> >      >      > On Fri, Aug 2, 2019 at 11:03 AM Joel M. Halpern
>>>>> >      >     <jmh@joelhalpern.com <mailto:jmh@joelhalpern.com>
>>>>> >     <mailto:jmh@joelhalpern.com <mailto:jmh@joelhalpern.com>>
>>>>> >      >      > <mailto:jmh@joelhalpern.com <mailto:
>>>>> jmh@joelhalpern.com>
>>>>> >     <mailto:jmh@joelhalpern.com <mailto:jmh@joelhalpern.com>>>>
>>>>> wrote:
>>>>> >      >      >
>>>>> >      >      >     If I am reading your various emails correctly
>>>>> Dinesh
>>>>> >     (and I
>>>>> >      >     may have
>>>>> >      >      >     missed something) you are trying to use the MAC
>>>>> address
>>>>> >      >     because you
>>>>> >      >      >     want
>>>>> >      >      >     to be able to send these BFD packets over
>>>>> arbitrary VNI to
>>>>> >      >     monitor the
>>>>> >      >      >     VNI.  That is not a requirement identified in the
>>>>> >     document.
>>>>> >      >     It is not
>>>>> >      >      >     even a problem I understand, since all the VNI
>>>>> between an
>>>>> >      >     ingress and
>>>>> >      >      >     egress VTEP share fate.
>>>>> >      >      >
>>>>> >      >      >     Yours,
>>>>> >      >      >     Joel
>>>>> >      >      >
>>>>> >      >      >     On 8/2/2019 1:44 PM, Dinesh Dutt wrote:
>>>>> >      >      >      > Thanks for verifying this. On Linux and hardware
>>>>> >     routers
>>>>> >      >     that I'm
>>>>> >      >      >     aware
>>>>> >      >      >      > of (Cisco circa 2012 and Cumulus), the physical
>>>>> MAC
>>>>> >     address is
>>>>> >      >      >     reused
>>>>> >      >      >      > across the VNIs on the VTEP. Did you check on a
>>>>> non-VMW
>>>>> >      >     device?
>>>>> >      >      >     This is
>>>>> >      >      >      > more for my own curiosity.
>>>>> >      >      >      >
>>>>> >      >      >      > To address the general case, can we not define a
>>>>> >      >     well-known (or
>>>>> >      >      >     reserve
>>>>> >      >      >      > one) unicast MAC address for use with VTEP? If
>>>>> the MAC
>>>>> >      >     address is
>>>>> >      >      >      > configurable in BFD command, this can be moot.
>>>>> >      >      >      >
>>>>> >      >      >      > Dinesh
>>>>> >      >      >      >
>>>>> >      >      >      > On Fri, Aug 2, 2019 at 10:27 AM Santosh P K
>>>>> >      >      >      > <santosh.pallagatti@gmail.com
>>>>> >     <mailto:santosh.pallagatti@gmail.com>
>>>>> >      >     <mailto:santosh.pallagatti@gmail.com
>>>>> >     <mailto:santosh.pallagatti@gmail.com>>
>>>>> >      >      >     <mailto:santosh.pallagatti@gmail.com
>>>>> >     <mailto:santosh.pallagatti@gmail.com>
>>>>> >      >     <mailto:santosh.pallagatti@gmail.com
>>>>> >     <mailto:santosh.pallagatti@gmail.com>>>
>>>>> >      >      >     <mailto:santosh.pallagatti@gmail.com
>>>>> >     <mailto:santosh.pallagatti@gmail.com>
>>>>> >      >     <mailto:santosh.pallagatti@gmail.com
>>>>> >     <mailto:santosh.pallagatti@gmail.com>>
>>>>> >      >      >     <mailto:santosh.pallagatti@gmail.com
>>>>> >     <mailto:santosh.pallagatti@gmail.com>
>>>>> >      >     <mailto:santosh.pallagatti@gmail.com
>>>>> >     <mailto:santosh.pallagatti@gmail.com>>>>> wrote:
>>>>> >      >      >      >
>>>>> >      >      >      >     I have cross checked point raised about MAC
>>>>> address
>>>>> >      >     usage. It is
>>>>> >      >      >      >     possible that tenant could be using
>>>>> physical MAC
>>>>> >      >     address and
>>>>> >      >      >     when a
>>>>> >      >      >      >     packet comes with valid VNI with a MAC
>>>>> address
>>>>> >     that is
>>>>> >      >     being
>>>>> >      >      >     used by
>>>>> >      >      >      >     tenant then packet will be sent to that
>>>>> tenant.
>>>>> >     This rules
>>>>> >      >      >     out the
>>>>> >      >      >      >     fact that we could use physical MAC address
>>>>> as
>>>>> >     inner
>>>>> >      >     MAC to
>>>>> >      >      >     ensure
>>>>> >      >      >      >     packets get terminated at VTEP itself.
>>>>> >      >      >      >
>>>>> >      >      >      >     Thanks
>>>>> >      >      >      >     Santosh P K
>>>>> >      >      >      >
>>>>> >      >      >      >     On Wed, Jul 31, 2019 at 11:00 AM Santosh P K
>>>>> >      >      >      >     <santosh.pallagatti@gmail.com
>>>>> >     <mailto:santosh.pallagatti@gmail.com>
>>>>> >      >     <mailto:santosh.pallagatti@gmail.com
>>>>> >     <mailto:santosh.pallagatti@gmail.com>>
>>>>> >      >      >     <mailto:santosh.pallagatti@gmail.com
>>>>> >     <mailto:santosh.pallagatti@gmail.com>
>>>>> >      >     <mailto:santosh.pallagatti@gmail.com
>>>>> >     <mailto:santosh.pallagatti@gmail.com>>>
>>>>> >      >      >     <mailto:santosh.pallagatti@gmail.com
>>>>> >     <mailto:santosh.pallagatti@gmail.com>
>>>>> >      >     <mailto:santosh.pallagatti@gmail.com
>>>>> >     <mailto:santosh.pallagatti@gmail.com>>
>>>>> >      >      >     <mailto:santosh.pallagatti@gmail.com
>>>>> >     <mailto:santosh.pallagatti@gmail.com>
>>>>> >      >     <mailto:santosh.pallagatti@gmail.com
>>>>> >     <mailto:santosh.pallagatti@gmail.com>>>>>
>>>>> >      >      >      >     wrote:
>>>>> >      >      >      >
>>>>> >      >      >      >         Joel,
>>>>> >      >      >      >             Thanks for your inputs. I checked
>>>>> >      >     implementation within
>>>>> >      >      >      >         Vmware. Perhaps I should have been more
>>>>> clear
>>>>> >      >     about MAC
>>>>> >      >      >     address
>>>>> >      >      >      >         space while checking internally. I will
>>>>> cross
>>>>> >      >     check again for
>>>>> >      >      >      >         the same and get back on this list.
>>>>> >      >      >      >
>>>>> >      >      >      >         Thanks
>>>>> >      >      >      >         Santosh P K
>>>>> >      >      >      >
>>>>> >      >      >      >         On Wed, Jul 31, 2019 at 10:54 AM Joel M.
>>>>> >     Halpern
>>>>> >      >      >      >         <jmh@joelhalpern.com
>>>>> >     <mailto:jmh@joelhalpern.com> <mailto:jmh@joelhalpern.com
>>>>> >     <mailto:jmh@joelhalpern.com>>
>>>>> >      >     <mailto:jmh@joelhalpern.com <mailto:jmh@joelhalpern.com>
>>>>> >     <mailto:jmh@joelhalpern.com <mailto:jmh@joelhalpern.com>>>
>>>>> >      >      >     <mailto:jmh@joelhalpern.com
>>>>> >     <mailto:jmh@joelhalpern.com> <mailto:jmh@joelhalpern.com
>>>>> >     <mailto:jmh@joelhalpern.com>>
>>>>> >      >     <mailto:jmh@joelhalpern.com <mailto:jmh@joelhalpern.com>
>>>>> >     <mailto:jmh@joelhalpern.com <mailto:jmh@joelhalpern.com>>>>>
>>>>> wrote:
>>>>> >      >      >      >
>>>>> >      >      >      >             Sorry to ask a stupid question.
>>>>> Whose
>>>>> >      >     implementation?
>>>>> >      >      >      >
>>>>> >      >      >      >             The reason I ask is that as far as I
>>>>> >     can tell,
>>>>> >      >     since the
>>>>> >      >      >      >             tenant does not
>>>>> >      >      >      >             have any control access to the VTEP,
>>>>> >     there is no
>>>>> >      >      >     reason for
>>>>> >      >      >      >             the VTEP to
>>>>> >      >      >      >             have a MAC address in the tenant
>>>>> >     space.  Yes, the
>>>>> >      >      >     device has
>>>>> >      >      >      >             a physical
>>>>> >      >      >      >             MAC address.  But the tenant could
>>>>> well be
>>>>> >      >     using that MAC
>>>>> >      >      >      >             address.  Yes,
>>>>> >      >      >      >             they would be violating the
>>>>> Ethernet spec.
>>>>> >      >     But the whole
>>>>> >      >      >      >             point of
>>>>> >      >      >      >             segregation is not to care about
>>>>> such
>>>>> >     issues.
>>>>> >      >      >      >
>>>>> >      >      >      >             On the other hand, if you tell me
>>>>> that
>>>>> >     the VMWare
>>>>> >      >      >      >             implementation has an
>>>>> >      >      >      >             Ethernet address that is part of
>>>>> the tenant
>>>>> >      >     space, well,
>>>>> >      >      >      >             they made up
>>>>> >      >      >      >             this particular game.
>>>>> >      >      >      >
>>>>> >      >      >      >             Yours,
>>>>> >      >      >      >             Joel
>>>>> >      >      >      >
>>>>> >      >      >      >             On 7/31/2019 1:44 PM, Santosh P K
>>>>> wrote:
>>>>> >      >      >      >              > I have checked with
>>>>> implementation
>>>>> >     in data
>>>>> >      >     path.
>>>>> >      >      >     When we
>>>>> >      >      >      >             receive a
>>>>> >      >      >      >              > packet with valid VNI then lookup
>>>>> >     for MAC will
>>>>> >      >      >     happen and
>>>>> >      >      >      >             it is VTEP own
>>>>> >      >      >      >              > MAC then it will be trapped to
>>>>> control
>>>>> >      >     plane for
>>>>> >      >      >      >             processing. I think we
>>>>> >      >      >      >              > can have following options
>>>>> >      >      >      >              > 1. Optional managment VNI
>>>>> >      >      >      >              > 2. Mandatory inner MAC set to
>>>>> VTEP mac
>>>>> >      >      >      >              > 3. Inner IP TTL set to 1 to avoid
>>>>> >      >     forwarding of packet
>>>>> >      >      >      >             via inner IP
>>>>> >      >      >      >              > address.
>>>>> >      >      >      >              >
>>>>> >      >      >      >              >
>>>>> >      >      >      >              > Thoughts?
>>>>> >      >      >      >              >
>>>>> >      >      >      >              > Thansk
>>>>> >      >      >      >              > Santosh P K
>>>>> >      >      >      >              >
>>>>> >      >      >      >              > On Wed, Jul 31, 2019 at 9:20 AM
>>>>> Greg
>>>>> >     Mirsky
>>>>> >      >      >      >             <gregimirsky@gmail.com
>>>>> >     <mailto:gregimirsky@gmail.com>
>>>>> >      >     <mailto:gregimirsky@gmail.com <mailto:
>>>>> gregimirsky@gmail.com>>
>>>>> >     <mailto:gregimirsky@gmail.com <mailto:gregimirsky@gmail.com>
>>>>> >      >     <mailto:gregimirsky@gmail.com <mailto:
>>>>> gregimirsky@gmail.com>>>
>>>>> >      >      >     <mailto:gregimirsky@gmail.com
>>>>> >     <mailto:gregimirsky@gmail.com> <mailto:gregimirsky@gmail.com
>>>>> >     <mailto:gregimirsky@gmail.com>>
>>>>> >      >     <mailto:gregimirsky@gmail.com <mailto:
>>>>> gregimirsky@gmail.com>
>>>>> >     <mailto:gregimirsky@gmail.com <mailto:gregimirsky@gmail.com>>>>
>>>>> >      >      >      >              > <mailto:gregimirsky@gmail.com
>>>>> >     <mailto:gregimirsky@gmail.com>
>>>>> >      >     <mailto:gregimirsky@gmail.com <mailto:
>>>>> gregimirsky@gmail.com>>
>>>>> >      >      >     <mailto:gregimirsky@gmail.com
>>>>> >     <mailto:gregimirsky@gmail.com> <mailto:gregimirsky@gmail.com
>>>>> >     <mailto:gregimirsky@gmail.com>>>
>>>>> >      >      >      >             <mailto:gregimirsky@gmail.com
>>>>> >     <mailto:gregimirsky@gmail.com>
>>>>> >      >     <mailto:gregimirsky@gmail.com <mailto:
>>>>> gregimirsky@gmail.com>>
>>>>> >      >      >     <mailto:gregimirsky@gmail.com
>>>>> >     <mailto:gregimirsky@gmail.com>
>>>>> >      >     <mailto:gregimirsky@gmail.com
>>>>> >     <mailto:gregimirsky@gmail.com>>>>>> wrote:
>>>>> >      >      >      >              >
>>>>> >      >      >      >              >     Hi Dinesh,
>>>>> >      >      >      >              >     thank you for your
>>>>> consideration
>>>>> >     of the
>>>>> >      >      >     proposal and
>>>>> >      >      >      >             questions. What
>>>>> >      >      >      >              >     would you see as the scope of
>>>>> >     testing the
>>>>> >      >      >      >             connectivity for the
>>>>> >      >      >      >              >     specific VNI? If it is
>>>>> >      >     tenant-to-tenant, then
>>>>> >      >      >     VTEPs
>>>>> >      >      >      >             will treat these
>>>>> >      >      >      >              >     packets as regular user
>>>>> frames. More
>>>>> >      >     likely, these
>>>>> >      >      >      >             could be Layer 2
>>>>> >      >      >      >              >     OAM, e.g. CCM frames. The
>>>>> reason
>>>>> >     to use
>>>>> >      >     127/8 for
>>>>> >      >      >      >             IPv4, and
>>>>> >      >      >      >              >     0:0:0:0:0:FFFF:7F00:0/104 for
>>>>> >     IPv6 is
>>>>> >      >     to safeguard
>>>>> >      >      >      >             from leaking
>>>>> >      >      >      >              >     Ethernet frames with BFD
>>>>> Control
>>>>> >     packet
>>>>> >      >     to a
>>>>> >      >      >     tenant.
>>>>> >      >      >      >              >     You've suggested using a MAC
>>>>> >     address to
>>>>> >      >     trap the
>>>>> >      >      >      >             control packet at
>>>>> >      >      >      >              >     VTEP. What that address
>>>>> could be? We
>>>>> >      >     had proposed
>>>>> >      >      >      >             using the
>>>>> >      >      >      >              >     dedicated MAC and VTEP's MAC
>>>>> and
>>>>> >     both
>>>>> >      >     raised
>>>>> >      >      >     concerns
>>>>> >      >      >      >             among VXLAN
>>>>> >      >      >      >              >     experts. The idea of using
>>>>> >     Management
>>>>> >      >     VNI may
>>>>> >      >      >     be more
>>>>> >      >      >      >             acceptable
>>>>> >      >      >      >              >     based on its similarity to
>>>>> the
>>>>> >     practice
>>>>> >      >     of using
>>>>> >      >      >      >             Management VLAN.
>>>>> >      >      >      >              >
>>>>> >      >      >      >              >     Regards,
>>>>> >      >      >      >              >     Greg
>>>>> >      >      >      >              >
>>>>> >      >      >      >              >     On Wed, Jul 31, 2019 at
>>>>> 12:03 PM
>>>>> >     Dinesh
>>>>> >      >     Dutt
>>>>> >      >      >      >             <didutt@gmail.com
>>>>> >     <mailto:didutt@gmail.com> <mailto:didutt@gmail.com
>>>>> >     <mailto:didutt@gmail.com>>
>>>>> >      >     <mailto:didutt@gmail.com <mailto:didutt@gmail.com>
>>>>> >     <mailto:didutt@gmail.com <mailto:didutt@gmail.com>>>
>>>>> >      >      >     <mailto:didutt@gmail.com <mailto:didutt@gmail.com>
>>>>> >     <mailto:didutt@gmail.com <mailto:didutt@gmail.com>>
>>>>> >      >     <mailto:didutt@gmail.com <mailto:didutt@gmail.com>
>>>>> >     <mailto:didutt@gmail.com <mailto:didutt@gmail.com>>>>
>>>>> >      >      >      >              >     <mailto:didutt@gmail.com
>>>>> >     <mailto:didutt@gmail.com>
>>>>> >      >     <mailto:didutt@gmail.com <mailto:didutt@gmail.com>>
>>>>> >      >      >     <mailto:didutt@gmail.com <mailto:didutt@gmail.com>
>>>>> >     <mailto:didutt@gmail.com <mailto:didutt@gmail.com>>>
>>>>> >      >     <mailto:didutt@gmail.com <mailto:didutt@gmail.com>
>>>>> >     <mailto:didutt@gmail.com <mailto:didutt@gmail.com>>
>>>>> >      >      >     <mailto:didutt@gmail.com <mailto:didutt@gmail.com>
>>>>> >     <mailto:didutt@gmail.com <mailto:didutt@gmail.com>>>>>>
>>>>> >      >      >      >             wrote:
>>>>> >      >      >      >              >
>>>>> >      >      >      >              >         Hi Greg,
>>>>> >      >      >      >              >
>>>>> >      >      >      >              >         As long as the inner MAC
>>>>> >     address is
>>>>> >      >     such
>>>>> >      >      >     that the
>>>>> >      >      >      >             packet is
>>>>> >      >      >      >              >         trapped to the CPU, it
>>>>> should be
>>>>> >      >     fine for
>>>>> >      >      >     use as
>>>>> >      >      >      >             an inner MAC is
>>>>> >      >      >      >              >         it not? Stating that is
>>>>> >     better than
>>>>> >      >     trying to
>>>>> >      >      >      >             force a management
>>>>> >      >      >      >              >         VNI. What if someone
>>>>> wants
>>>>> >     to test
>>>>> >      >      >     connectivity
>>>>> >      >      >      >             on a specific
>>>>> >      >      >      >              >         VNI? I would not pick a
>>>>> >     loopback IP
>>>>> >      >      >     address for
>>>>> >      >      >      >             this since that
>>>>> >      >      >      >              >         address range is
>>>>> host/node local
>>>>> >      >     only. Is
>>>>> >      >      >     there a
>>>>> >      >      >      >             reason you're
>>>>> >      >      >      >              >         not using the VTEP IP as
>>>>> the
>>>>> >     inner IP
>>>>> >      >      >     address ?
>>>>> >      >      >      >              >
>>>>> >      >      >      >              >         Dinesh
>>>>> >      >      >      >              >
>>>>> >      >      >      >              >         On Wed, Jul 31, 2019 at
>>>>> 5:48 AM
>>>>> >      >     Greg Mirsky
>>>>> >      >      >      >              >         <gregimirsky@gmail.com
>>>>> >     <mailto:gregimirsky@gmail.com>
>>>>> >      >     <mailto:gregimirsky@gmail.com <mailto:
>>>>> gregimirsky@gmail.com>>
>>>>> >      >      >     <mailto:gregimirsky@gmail.com
>>>>> >     <mailto:gregimirsky@gmail.com> <mailto:gregimirsky@gmail.com
>>>>> >     <mailto:gregimirsky@gmail.com>>>
>>>>> >      >      >      >             <mailto:gregimirsky@gmail.com
>>>>> >     <mailto:gregimirsky@gmail.com>
>>>>> >      >     <mailto:gregimirsky@gmail.com <mailto:
>>>>> gregimirsky@gmail.com>>
>>>>> >      >      >     <mailto:gregimirsky@gmail.com
>>>>> >     <mailto:gregimirsky@gmail.com>
>>>>> >      >     <mailto:gregimirsky@gmail.com
>>>>> >     <mailto:gregimirsky@gmail.com>>>> <mailto:gregimirsky@gmail.com
>>>>> >     <mailto:gregimirsky@gmail.com>
>>>>> >      >     <mailto:gregimirsky@gmail.com <mailto:
>>>>> gregimirsky@gmail.com>>
>>>>> >      >      >     <mailto:gregimirsky@gmail.com
>>>>> >     <mailto:gregimirsky@gmail.com> <mailto:gregimirsky@gmail.com
>>>>> >     <mailto:gregimirsky@gmail.com>>>
>>>>> >      >      >      >             <mailto:gregimirsky@gmail.com
>>>>> >     <mailto:gregimirsky@gmail.com>
>>>>> >      >     <mailto:gregimirsky@gmail.com <mailto:
>>>>> gregimirsky@gmail.com>>
>>>>> >      >      >     <mailto:gregimirsky@gmail.com
>>>>> >     <mailto:gregimirsky@gmail.com>
>>>>> >      >     <mailto:gregimirsky@gmail.com
>>>>> >     <mailto:gregimirsky@gmail.com>>>>>> wrote:
>>>>> >      >      >      >              >
>>>>> >      >      >      >              >             Dear All,
>>>>> >      >      >      >              >             thank you for your
>>>>> comments,
>>>>> >      >      >     suggestions on
>>>>> >      >      >      >             this issue,
>>>>> >      >      >      >              >             probably the most
>>>>> >     challenging
>>>>> >      >     for this
>>>>> >      >      >      >             specification. In the
>>>>> >      >      >      >              >             course of our
>>>>> discussions,
>>>>> >      >     we've agreed to
>>>>> >      >      >      >             abandon the
>>>>> >      >      >      >              >             request to allocate
>>>>> the
>>>>> >      >     dedicated MAC
>>>>> >      >      >     address
>>>>> >      >      >      >             to be used as
>>>>> >      >      >      >              >             the destination MAC
>>>>> >     address in
>>>>> >      >     the inner
>>>>> >      >      >      >             Ethernet frame.
>>>>> >      >      >      >              >             Also, earlier using
>>>>> VNI
>>>>> >     0 was
>>>>> >      >     changed from
>>>>> >      >      >      >             mandatory to one
>>>>> >      >      >      >              >             of the options an
>>>>> >      >     implementation may
>>>>> >      >      >     offer to
>>>>> >      >      >      >             an operator.
>>>>> >      >      >      >              >             The most recent
>>>>> >     discussion was
>>>>> >      >     whether
>>>>> >      >      >     VTEP's
>>>>> >      >      >      >             MAC address
>>>>> >      >      >      >              >             might be used as the
>>>>> >      >     destination MAC
>>>>> >      >      >     address
>>>>> >      >      >      >             in the inner
>>>>> >      >      >      >              >             Ethernet frame. As I
>>>>> >     recall it, the
>>>>> >      >      >     comments
>>>>> >      >      >      >             from VXLAN
>>>>> >      >      >      >              >             experts equally split
>>>>> >     with one
>>>>> >      >     for it
>>>>> >      >      >     and one
>>>>> >      >      >      >             against. Hence
>>>>> >      >      >      >              >             I would like to
>>>>> propose
>>>>> >     a new
>>>>> >      >     text to
>>>>> >      >      >     resolve
>>>>> >      >      >      >             the issue. The
>>>>> >      >      >      >              >             idea is to let an
>>>>> >     operator select
>>>>> >      >      >     Management
>>>>> >      >      >      >             VNI and use
>>>>> >      >      >      >              >             that VNI in VXLAN
>>>>> >     encapsulation
>>>>> >      >     of BFD
>>>>> >      >      >      >             Control packets:
>>>>> >      >      >      >              >             NEW TEXT:
>>>>> >      >      >      >              >
>>>>> >      >      >      >              >                 An operator MUST
>>>>> >     select a VNI
>>>>> >      >      >     number to
>>>>> >      >      >      >             be used as
>>>>> >      >      >      >              >                 Management VNI.
>>>>> VXLAN
>>>>> >      >     packet for
>>>>> >      >      >      >             Management VNI MUST NOT
>>>>> >      >      >      >              >                 be sent to a
>>>>> tenant. VNI
>>>>> >      >     number 1 is
>>>>> >      >      >      >             RECOMMENDED as the
>>>>> >      >      >      >              >                 default for
>>>>> >     Management VNI.
>>>>> >      >      >      >              >
>>>>> >      >      >      >              >             With that new text,
>>>>> what
>>>>> >     can be the
>>>>> >      >      >     value of
>>>>> >      >      >      >             the destination
>>>>> >      >      >      >              >             MAC in the inner
>>>>> Ethernet? I
>>>>> >      >     tend to
>>>>> >      >      >     believe
>>>>> >      >      >      >             that it can be
>>>>> >      >      >      >              >             anything and ignored
>>>>> by the
>>>>> >      >     reciever VTEP.
>>>>> >      >      >      >             Also, if the
>>>>> >      >      >      >              >             trapping is based on
>>>>> VNI
>>>>> >      >     number, the
>>>>> >      >      >      >             destination IP address
>>>>> >      >      >      >              >             of the inner IP
>>>>> packet
>>>>> >     can from
>>>>> >      >     the range
>>>>> >      >      >      >             127/8 for IPv4,
>>>>> >      >      >      >              >             and for IPv6 from
>>>>> the range
>>>>> >      >      >      >             0:0:0:0:0:FFFF:7F00:0/104. And
>>>>> >      >      >      >              >             lastly, the TTL to be
>>>>> >     set to 1 (no
>>>>> >      >      >     change here).
>>>>> >      >      >      >              >
>>>>> >      >      >      >              >             Much appreciate your
>>>>> >     comments,
>>>>> >      >      >     questions, and
>>>>> >      >      >      >             suggestions.
>>>>> >      >      >      >              >
>>>>> >      >      >      >              >             Best regards,
>>>>> >      >      >      >              >             Greg
>>>>> >      >      >      >              >
>>>>> >      >      >      >
>>>>> >      >      >
>>>>> >      >
>>>>> >
>>>>>
>>>>