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).
Also, even if ICMP delivery is assured, there are additional
complications for UDP, which has been seeing a lot of interest both
as a tunneling encapsulation and for applications (e.g., QUIC). Many
platforms do not provide UDP-sending applications any information
about arriving ICMP messages that were triggered by their
transmissions. So even if the path delivers ICMP, the OS makes
ICMP-based PMTUD for UDP often impossible. Another reason to
recommend 4821?
Agreed... although in this case this would be more of an app-layer
implementation than one at the transport layer?
Thanks,
--
Fernando Gont
SI6 Networks
e-mail: fgont(_at_)si6networks(_dot_)com
PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492