On 02/02/2017 09:18 PM, Brian E Carpenter wrote:
On 02/02/2017 22:54, Fernando Gont wrote:
Hi, Lars,
On 02/02/2017 06:37 AM, Eggert, Lars wrote:
Hi,
the last paragraph of the introduction reads:
An extension to Path MTU Discovery defined in this document can be
found in [RFC4821]. It defines a method for Packetization Layer
Path MTU Discovery (PLPMTUD) designed for use over paths where
delivery of ICMP messages to a host is not assured.
Given that ICMP delivery cannot be assured over the vast majority of
paths in the current Internet, should this document make a
recommendation to implement RFC4821?
I think that RFC4821 should be recommended, at least for dealing with
ICMP blackholes (i.e., use ICMP if you can, but be able to deal with
scenarios in which you don't receive them).
Many people think that, but this draft is constrained by the rules in
RFC6410 about "high degree of technical maturity" and "widespread
deployment" in the move from PS to Standard. Adding new stuff is not
supposed to happen. If I recall correctly, the WG tuned the language
to its present state for that reason.
My apologies: my comments were probably misleading. Certainly, this
document is simply RFC1981 to Std, and hence recommending RFC4821 would
be kind of ou of scope, here.
That say, one might wonder to what extent, and for the general Internet,
RFC1981 can be considered succesful (given the filtering of ICMP
messages). -- i.e., at this point in time you wouldn't rely on RFC1981
(icmp-based pmtud) for path-mtu discovery.
Cheers,
--
Fernando Gont
SI6 Networks
e-mail: fgont(_at_)si6networks(_dot_)com
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