Sysplex Distributor showing increasing number out outbound errors in NETSTAT DEVLINK
SYSTCPIP CTRACE shows CSDUMP shows the inbound 1492 sized packets were wrapped by GRE Tunnel headers adding 24 bytes to the original size.
The resulting GRE packet is too large to fit on the outbound ethernet and would have to be fragmented. As PMTUD was enabled the IP header had the
DF bit set to IP Fragmentation was not allowed.
VTAM Internal Trace shows large packets being dropped in SD due to Fragmentation required but not allowed.