Troubleshooting
Problem
Path MTU Discovery ( PMTUD ) with IPsec
Symptom
Packets sent with PMTUD ( Don't Fragment bit on ) are receiving an ICMP message, type 3, code 4.
This means that fragmentation is needed, but don't-fragment bit is set.
Cause
The IBM i IPsec implementation does not process ICMP error packets with an IPsec original datagram
Diagnosing The Problem
Path MTU Discovery ( PMTUD ) with IPsec using transport mode or tunnel mode is not supported
Resolving The Problem
Create a route with an MTU small enough for the path, that will avoid fragmentation.
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Document Information
Modified date:
18 December 2019
UID
nas8N1020625