Problem

-- when using MFP connector, such error can be seen during a peak of activity :

HME3_Procengine5(procengine(procmbc_CallMFP)):MFP.Connect: Can't assign requested address

Resolution

-- on B2Bi 2.6 SP2 and higher versions, you can set the CORE_MFP_CLIENT_LINGER_SECONDS environment variable to 0 or another small value to make sure such connections do not pile up in the TIME_WAIT state and exhaust the pool of local dynamic ports.
Setting this environment value to large values will make the MFP client hang for the specified number of seconds.
The recommended solution is to use persistent MFP connections if possible; using this environment variable with zero or small values may cause a few MFP connections to break when the MFP server is a remote machine