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Kazeem_Yusuf's avatar
Kazeem_Yusuf
Icon for Nimbostratus rankNimbostratus
Jul 14, 2026

An Irule that Stops TLS (tcp) Fragmentation on Client Side

There is a requirement to implement a service that extracts Inserted traffic in extension header from subscribers.  the insertion is done by PGW on packet core, and works on server side, which can su...
irule
LTM
tcp
tls1.2
tls1.3
Seattle2k's avatar
Seattle2k
Icon for Employee rankEmployee
Jul 28, 2026

If the receiving interface's MTU is 1500 bytes, then the max payload size is 1500 - 40 = 1460. Anything larger must be broken up / fragmented.   BIG-IP can set the DF bit, but a 1480-byte payload (1510-byte frame) is not going to fit through an interface set to 1500-bytes MTU.

As zamruni777 indicated, the solution is to increase MTU. Jumbo Frames allows ~9000 byte MTU. But remember, if these packets are being transmitted across the pubiic internet, they will eventually get fragmented out there.