The inner packet of a VxLAN header with a VNI is a tenant packet for the
tenant identified by the VNI. That is the meaning of the inner packet.
If you declare that the flag bits change that meaning, then that flag
bit has to adjust the packet processing at the VTEP such taht it will
intercept the packet. As such, it doesn;t need special inner source or
dest mac addresses or IP addresses. In fact, the inner packet can just
be OAM payload.
If that is not what you intend, then how is it that the VTEP knows that
the inner addresses are for it to examine, rather than belonging to the
tenant. As far as I know we are not free to take addresses away from
the tenant.
It may be that I am completely missing how this is supposed to work. If
so, it needs better explanation.
Yours,
Joel
On 6/5/19 5:20 PM, Greg Mirsky wrote:
Hi Joel,
thank you for your review and the pointed questions. Please find my
answers, comments in-line and tagged GIM>>.
Regards,
Greg
On Thu, May 23, 2019 at 3:06 PM Joel Halpern via Datatracker
<noreply@xxxxxxxx <mailto:noreply@xxxxxxxx>> wrote:
Reviewer: Joel Halpern
Review result: Has Issues
Hello,
I have been selected as the Routing Directorate reviewer for this
draft. The
Routing Directorate seeks to review all routing or routing-related
drafts as
they pass through IETF last call and IESG review, and sometimes on
special
request. The purpose of the review is to provide assistance to the
Routing ADs.
For more information about the Routing Directorate, please see
http://trac.tools.ietf.org/area/rtg/trac/wiki/RtgDir
Although these comments are primarily for the use of the Routing
ADs, it would
be helpful if you could consider them along with any other IETF Last
Call
comments that you receive, and strive to resolve them through
discussion or by
updating the draft.
Document: ddraft-ietf-bfd-vxlan-07
Reviewer: your-name
Review Date: date
IETF LC End Date: date-if-known
Intended Status: copy-from-I-D
Summary: This document does not appear to be ready for publication as a
Proposed Standard RFC.
Major issues:
The scoping of the BFD usage is unclear. In places, this looks
like it is
intended to be used by the underlay service provider, who will
monitor the
connectivity between VTEPs.
GIM>> I think that the DCI provider would not be able to instantiate a
BFD session using VXLAN encapsulation and, possibly, monitor that VXLAN
part of forwarding operates properly. Such BFD session may monitor the
path between the two VTEP but, if there exists ECMP environment in the
transport, ensuring that that BFD session follows the same path as VXLAN
data may be challenging.
In other places it seems to be aimed at
monitoring individual VNIs.
GIM>> The BFD session between VTEPs is not actually used to monitor the
particular VNI but MAY be used to communicate, as concatenated path
state signaling, the change of VNI state using the method described in
Section 6.8.17 RFC 5880
<https://tools.ietf.org/html/rfc5880#section-6.8.17>.
This is made worse when the packet format is
laid out. The inner packet is an Ethernet Packet with an IP
packet (with
UDP, with BFD). This means that it is a tenant packet.
GIM>> Could you please point to the text which suggests that the BFD
control packet is a tenant packet? Meant to be delivered to a tenant?
The IP address is
a tenant IP.
GIM>> The explanation of the format states in regard to the inner IP header:
IP header:
Source IP: IP address of the originating VTEP.
Destination IP: IP address of the terminating VTEP.
But the diagram shows this as being the IP address of the
VTEP. Which is not a tenant entity.
There is further confusion as to whether the processing is
driven by the VNI
the packet arrived with, or the VNI is ignored.
GIM>> The use of VNI is implementation specific. Section 6 states:
6. Use of the Specific VNI
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 the reachability of the remote VTEP, an implementation SHOULD
choose any of the VNIs but MAY choose VNI = 0.
Minor Issues:
N/A
Nits: N/A
