[SR-Users] tcp hangup

i have two sr proxies talking with each other over tcp. one is running 3.0 and the other 3.1. sometimes i notice that no sip requests or any other tcp packets get through from 3.0 sr host to 3.1 sr host. netstat on 3.0 sr host shows that tcp connection to 3.1 sr host is in ESTABLISHED state whereas netstat on 3.1 sr shows that the same tcp connection is in FIN_WAIT1 state. it takes several minutes before the hanging tcp connection is replaced by a new working one. there is no ip level connectivity problem between the two sr hosts. any suggestions on what might be going on? is there some known bug in 3.0 tcp implementation that could explain this? -- juha