Turning to the dataplane requirements draft, here's proposed elaboration
text for the path MTU material in section 3.5 (no change to the second and
third bullet items - they're included for completeness):
OLD
Either of the following options MUST be supported:
o Classical ICMP-based MTU Path Discovery [RFC1191] [RFC1981] or
Extended MTU Path Discovery techniques such as defined in
[RFC4821]
o Segmentation and reassembly support from the overlay layer
operations without relying on the Tenant Systems to know about
the end-to-end MTU
o The underlay network MAY be designed in such a way that the MTU
can accommodate the extra tunnel overhead.
NEW
At least one of the following options MUST be supported:
o Classical ICMP-based MTU Path Discovery [RFC1191] [RFC1981] or
Extended MTU Path Discovery techniques such as defined in
[RFC4821]. Both techniques are based on use of probe packets.
Classical MTU Path Discovery requires ICMP responses from
the underlay network. Extended MTU Path Discovery requires
detection of probe packet loss at the receiver and means to
communicate that loss to the sender.
o Segmentation and reassembly support from the overlay layer
operations without relying on the Tenant Systems to know about
the end-to-end MTU
o The underlay network MAY be designed in such a way that the MTU
can accommodate the extra tunnel overhead.
------------------------------
There's an additional question - what does that initial "MUST" ("At least
one of the following options MUST be supported:") apply to??
The framework draft text on this topic describes Tenant Systems using MTU
discovery techniques, whereas some of the options above apply to the nvo3
dataplane (e.g., overlay segmentation and reassembly could reside in NVEs).
Thanks,
--David
----------------------------------------------------
David L. Black, Distinguished Engineer
EMC Corporation, 176 South St., Hopkinton, MA 01748
+1 (508) 293-7953 FAX: +1 (508) 293-7786
[email protected] Mobile: +1 (978) 394-7754
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