Forum Discussion

DR2016_253175's avatar
DR2016_253175
Icon for Nimbostratus rankNimbostratus
Mar 07, 2016

Maximum number of TCP connections to LTM - is there a limit?

Hello, I am wondering if there is any system level restriction on the maximum number of TCP connections that can be opened to an LTM version 10.2.4 and 11.5.2. Is the limit determined by the system m...
BIG-IP
connection limit
LTM
security
tcp
Hannes_Rapp's avatar
Hannes_Rapp
Icon for Nimbostratus rankNimbostratus
Mar 08, 2016

Yes, the platform itself/available memory determines the max number of records that can be held in the connection table. F5 has the estimate limits available in hardware datasheets.

There's another TCP/IP protocol-related limitation that you should consider if you explicitly translate client source IP addresses (Source NAT), before the requests are routed to BigIP.

The TCP/IP protocol has a limitation of 64k unique sessions 

from a single IP client (i.e. 1.1.1.1), to the same Server IP/Port listener (i.e 2.2.2.2:443)
. There's a dedicated 64k-unit-size range for TCP source ports that can be used by the client.