Jesse, I agree with your changes (of course).
Thx, Bob
On 09/07/16 00:00, Jesse Gross wrote:
Bob,
Thanks for reviewing the draft and your comments. I agree with what
you said and have changed the SHOULD to MUST and also the statement
about there being “several options” for DSCP and ECN to “several
considerations”. I just uploaded a new version of the draft (great
timing by the way as I was in the process of updating it today) that
reflects this.
Jesse
On 7/8/16, 9:02 AM, "Bob Briscoe" <[email protected]
<mailto:[email protected]>> wrote:
Jesse, Ilango,
Just checked
https://tools.ietf.org/html/draft-ietf-nvo3-geneve-01#section-4.1.2
It currently says:
[RFC6040] describes the mechanism for exposing ECN
capabilities on IP
tunnels and propagating congestion markers to the inner packets.
This behavior SHOULD be followed for IP packets encapsulated in
Geneve.
I'm afraid this has to be a MUST. Otherwise, if you don't follow
RFC6040, what do you implement instead?
The whole point of RFC6040 was to specify one single consistent
behaviour for all types of tunnel endpoints, with zero options, zero
config, zero management (unlike Diffserv).
So this statement a little earlier is also a bit wrong:
there are several options for propagating DSCP and ECN bits
ECN is now becoming popular in private DCs to keep buffer occupancy v
shallow (e.g. with DCTCP).
If a decapsulator doesn't propagate congestion notification at
all, it
black-holes it. Admittedly you have loss to fall back on...
eventually.
However, while ECN is black-holed sources carry on increasing their
rate, until they overflow the buffer. Particularly with pooled memory
for buffering that can introduce a huge amount of delay before
black-holed ECN turns into loss. Even if ECN isn't being used at the
moment, it must be implemented in case it starts to be used.
Cheers
Bob
--
________________________________________________________________
Bob Briscoe http://bobbriscoe.net/ <http://bobbriscoe.net/>
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Bob Briscoe http://bobbriscoe.net/
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