Subject: [Int-area] draft-bonica-intarea-frag-fragile-01

From: Mikael Abrahamsson <[email-masked]>
Date: Tue, 20 Mar 2018 10:19:59 +0100 (CET)

Hi,

as promised in v6ops, I will suggest text. The current -01 text is:

7.2.  For Network Operators

    As per RFC 4890, network operators MUST NOT filter ICMPv6 PTB
    messages unless they are known to be forged or otherwise
    illegitimate.  As stated in Section 4.5, filtering ICMPv6 PTB packets
    causes PMTUD to fail.  Many upper-layer protocols rely on PMTUD.

So perhaps text along these lines:

--
As per RFC 4890, network operators MUST NOT filter ICMPv6 PTB messages 
unless they are known to be forged or otherwise illegitimate. As stated in 
Section 4.5, filtering ICMPv6 PTB packets causes PMTUD to fail. Operators 
MUST ensure proper PMTUD operation in their network, including making sure 
the network generates PTB packets when dropping packets too large compared 
to outgoing interface MTU.

Many upper-layer protocols rely on PMTUD.
--

I have also encountered lots of people who think that as long as they do 
MSS capping, they don't have to worry about anything. Should we include 
text on their behalf?

Another thing, I would like to see text somewhere (perhaps 7.1) that 
states that protocols/applications should do PLMTUD. I would like to see 
TCP having this default on in all operating systems.

-- 
Mikael Abrahamsson    email: [email-masked]