Subject: [nvo3] New draft: PMTUD Over Vxlan

From: "Saumya Dikshit (sadikshi)" <[email-masked]>
Date: Tue, 30 Jun 2015 14:57:23 +0000

Hello All,

We have submitted a draft related to Path MTU Discovery in an end to end path,
between devices connected over a Vxlan network. The draft outlines existing
Problems and a potential solution to go around them, without tinkering with
existing standards.

https://datatracker.ietf.org/doc/draft-saum-nvo3-pmtud-over-vxlan/

Please provide your comments and suggestions on the same.

Thanks and Regards,
Saumya.

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From: Joe Touch <[email-masked]>
Date: Tue, 30 Jun 2015 10:12:22 -0700

This document makes several erroneous assumptions, IMO:

- 2.2: applications don't "tailor the MSS" (transport layers do)

- overall: PMTUD is deprecated, in favor of PLMTUD

-overall: in a tunneling system, the packetization layer is the tunnel
encapsulator, which means that layer should be doing MTU discovery

- 3.1: PTB ICMPs are generated when the packet size is greater than the
link MTU, not the other way around

- 3.1: IPv6 doesn't have a DF bit

- the overall approach misuses DF and PTB messages, IMO

These issues have been discussed repeatedly on the INTAREA mailing list.

Joe

On 6/30/2015 7:57 AM, Saumya Dikshit (sadikshi) wrote:
> _______________________________________________
> nvo3 mailing list
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From: "Saumya Dikshit (sadikshi)" <[email-masked]>
Date: Wed, 1 Jul 2015 03:29:30 +0000

Hi Joe,

Thanks for your comments. I will surely remove these references from
draft. 
Those were more of typo misses and shouldn¹t have been there in first
place.

The idea in this draft is to provide a solution, wherein
Vxlan gateway can translate the icmp errors (either PTB or Fragmentation)
generated in the underlay and pass it on to the end-point device.

Please see inline. 

Thanks
Saumya.

>encapsulator, which means that layer should be doing MTU discovery
<> Currently the provisioning of Vxlan is more of static provisioning and
hence
I don¹t think there is any such dynamic information exchange.

>link MTU, not the other way around
<> That¹s big typo miss. I will rectify it.
>- the overall approach misuses DF and PTB messages, IMO
<> That¹s again a typo miss. Let me remove reference of IPv6 wherever
DF-bit is mentioned.