Hi Wim,
2015-11-13, Henderickx, Wim (Wim):
Thomas, we can discuss forever and someone need to describe
requirements, but the current proposal I cannot agree to for the
reasons explained.
Well, although discussing forever is certainly not the goal, the reasons
for rejecting a proposal need to be thoroughly understood.
(more below)
2015-11-13, Henderickx, Wim (Wim):
Thomas, we need a solution that is implementable and will scale in
control/data-plane. As such the solution I outline is standardised
today and does not need new extensions in control/data-plane. Hence
informational draft and can be implemented if there is market demand.
The above argument would fully make sense to me if support
MPLS/MPLS/(UDP or GRE) was common place in ToRs or vswitches.
With respect to MAC you need to address both directions and does not
make sense to manage this if it is not required/doe snot add value.
On VXLAN and the Ethernet header: it looks to me that addressing both
direction is just a matter of documenting in the draft (if not already
there) what is the expected behavior for VXLAN/NVGRE. But VXLAN and
NVGRE are not the only encaps proposed in the specs anyway.
Compared to 3-label option C, my understanding is that the added-value
is to not require the support of an MPLS/MPLS/(UDP or GRE) encap in
ToRs and vswitches.
The right trade-off to make may in fact depend on whether you prefer:
(a) a new dataplane stitching behavior on DC ASBRs (the behavior
specified in this draft)
or (b) an evolution of the encaps on the vswitches and ToRs to support
MPLS/MPLS/(UDP or GRE)
WH> b depends on the use case
I don't get what you mean by "b depends on the use case".
I wrote the above based on the idea that the encap used in
MPLS/MPLS/(UDP or GRE), which hence has to be supported on the ToRs and
vswitches.
Another possibility would be service-label/middle-label/Ethernet
assuming an L2 adjacency between vswitches/ToRs and ASBRs, but this
certainly does not match your typical DC architecture. Or perhaps had
you something else in mind ?
WH> and depending on implementation you don’t need to change any of
the TOR/vswitches.
Does this mean that for some implementations you may not need to change
any of the TOR/vswitches, but that for some others you may ?
Let me take a practical example : while I can quite easily see how to
implement the procedures in draft-hao-bess-inter-nvo3-vpn-optionc based
on current vswitch implementations of VXLAN, the lack of MPLS/MPLS/(UDP,
GRE) support in commonplace vswitches seems to me as making that
alternate solution you suggest harder to implement.
-Thomas
From: Thomas Morin <[email protected]>
Organization: Orange
Date: Friday 13 November 2015 at 09:57
To: Wim Henderickx <[email protected]>
Cc: "[email protected]" <[email protected] <mailto:[email protected]>>
Subject: Re: [bess] draft-hao-bess-inter-nvo3-vpn-optionc
Hi Wim,
I agree on the analysis that this proposal is restricted to
implementations that supports the chosen encap with non-IANA ports
(which may be hard to achieve for instance on hardware
implementations, as you suggest), or to context where managing
multiple IPs would be operationally viable.
However, it does not seem obvious to me how the alternative you
propose [relying on 3-label option C with an MPLS/MPLS/(UDP|GRE)
encap] addresses the issue of whether the encap behavior is supported
or not (e.g. your typical ToR chipset possibly may not support this
kind of encap, and even software-based switches may not be ready to
support that today).
My take is that having different options to adapt to various
implementations constraints we may have would have value.
(+ one question below on VXLAN...)
-Thomas
2015-11-12, Henderickx, Wim (Wim):
On VXLAN/NVGRE, do you challenge the fact that they would be used
with a dummy MAC address that would be replaced by the right MAC by
a sender based on an ARP request when needed ?
Is the above the issue you had in mind about VXLAN and NVGRE ?
WH> yes
I you don't mind me asking : why do you challenge that ?
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