Hi Fred,

Inline.......

> 
> Message: 1
> Date: Mon, 23 Feb 2015 16:50:27 +0000
> From: "Templin, Fred L" <[email protected]>
> To: "[email protected]" <[email protected]>
> Subject: Re: [Int-area] draft-ietf-intarea-gre-ipv6
> Message-ID:
>       <2134F8430051B64F815C691A62D9831832DFB25B@XCH-BLV-
> 504.nw.nos.boeing.com>
> 
> Content-Type: text/plain; charset="us-ascii"
> 
> Hi, I have a comment on this document. 'draft-ietf-intarea-gre-ipv6' is very
> much in the same boat as RFC2473 in terms of MTU and Fragmentation
> considerations. So, why not just cite Sections 6.7 and 7 of RFC2473 instead of
> inventing new text here since the considerations are exactly the same?
> 
[RPB] 

RFC 2473 addresses the same problem for IP-in-IP encapsulation. It stands to 
reason that the two approaches would be similar. However, the text in RFC 2473 
is a proper subset of the text in Section 3.1 of draft-ietf-intarea-gre-ipv6. 
Since much of the text in draft-ietf-intarea-gre-ipv6 is new, for the sake of 
readability, it makes sense to restate the part that is also presented in RFC 
2473.

> But then, there would still be three problems inherent in both documents:
> 
> 1) There may be no way for the tunnel ingress to determine the MTU on
>      the path to the egress, e.g., if ICMP PTB messages are lost or somehow
>     forged by an attacker
> 
[RPB] 
Isn't loss or forgery of PTB messages a well-known issue for IPv6, regardless 
of whether any tunnels are involved?

> 2) ICMP PTB messages may be lost on the  return path from the tunnel
>     ingress to the original source
[RPB] 
Same comment as above
> 
> 3) Even in environments where 1) and 2) are not a matter of concern, the
>     original source could see an MTU smaller than 1500.
[RPB] 
This is addressed in Sections 4.1 of draft-ietf-intarea-gre-ipv6.

                                             Ron

> 
> These issues are addressed by Section 3.13 of 'draft-templin-aerolink', which
> is applicable for all tunneling environments.  What is in RFC2473 right now
> (and what 'draft-ietf-intarea-gre-ipv6' should be citing) is only applicable 
> for
> controlled environments.
> 
> Thanks - Fred
> [email protected]
> 

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