On Sat, Jun 08, 2019 at 05:08:54PM -0400, Jamon Camisso via talk wrote:
True enough, but it is also easy to check and determine whether it is an issue. I get a ticket or two a month with remote employees who are connecting from strange places, or have issues with VPNs, and quite a few are MTU related.
I'm curious about PMTUD now: my understanding is that ICMP needs to be unrestricted between server & client. If something is blocking that traffic how does it work? Also how does PTMUD handle asymmetric paths?
RFC 4890 explicitly says some types of ICMPv6 must not be filtered. They are: - Destination Unreachable (Type 1) - All codes - Packet Too Big (Type 2) - Time Exceeded (Type 3) - Code 0 only - Parameter Problem (Type 4) - Codes 1 and 2 only They also suggest echo request/response should be allowed. Anyone that filters the first ones will break IPv6. Some ISPs are unfortunately that crappy. -- Len Sorensen