Last Modified: Sep 13, 2023
Affected Product(s):
BIG-IP LTM
Known Affected Versions:
11.6.2 HF1
Fixed In:
11.6.0, 11.5.1 HF5
Opened: Apr 03, 2014 Severity: 3-Major
Excessive and slow ICMP and TCP traffic for afflicted flows
TSO does not generate properly-sized packets, triggering lots of re-transmissions. This creates unnecessary congestion and long data transfer times.
Routers in path send ICMP 'fragmentation required' packets informing the BIG-IP system of packet size limitations in the path; true path MTU is lower than what the TCP endpoints negotiated. The BIG-IP system enables TCP Segmentation Offload (TSO).
Disable TSO with the following command: 'tmsh modify sys db tm.tcpsegmentationoffload value disable'
Fixed improper handling of ICMP (Internet Control Message Protocol) 'Fragmentation Required' messages from routers. Bug resulted in extremely inefficient behavior by BIG-IP TCP segmentation offload if path MTU (Maximum Transmission Unit) was smaller than what TCP endpoints negotiated.