Sami, et al,

The draft-ietf-nvo3-encap-00 is written very clear.

However, the Section 6 (Common Encapsulation Considerations) should add a 
sub-section on the consideration of traversing NAPT.  Encapsulated traffic 
could go to different data centers or WAN, which could go through Network 
Address Port Translation devices

Using VxLAN as an example: VxLAN specification [RFC 7348] uses a set of Port 
numbers to achieve better traffic distribution among multiple paths, which is 
fine within one data center, but causing trouble when traversing NAPT. NAPT use 
Port number to map back the source address. With a set of port numbers, NAPT 
can't easily figure out the reverse direction traffic's final IP addresses.

In addition, since the IP of packets change through NAPT device, it can mess up 
the learning of the peer NVE used in encapsulation.

STUN can be used to get changed IP and port from NAPT device, but it requires 
NAPT device support STUN. That's not available in some scenarios. Furthermore, 
it can't solve the aforementioned five-tuple issue.

VXLAN over IPSec may be used to deal with the above problems, but IPSec brings 
up to 88 bytes of overhead plus the key distribution management, which can 
lower the efficiency.


Suggestion: Add Section 6.10 Traversing NAPT consideration.
I can help to provide the text if you all think the suggestion is acceptable.

We can discuss more in Prague.

Thanks, Linda Dunbar

Huawei USA IP Technology Lab
5340 Legacy Drive,
Plano, TX 75024
Tel: +1 469-277 - 5840
Fax: +1 469 -277 - 5900

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