Chapter 5: Troubleshooting5-12CyberSWITCH CSX400 and CSX400-DC Installation GuideSynchronous Polling Messages — The t391 timer for the ANSI/ITU Frame Relay forms thebasis for polling between the FR switch and the FR DTE (us). We transmit a STATUS ENQUIRYevery t391 seconds (10 by default) to the FR switch. We expect a STATUS RESPONSE, whichcontains information on the DLCIs the switch has assigned to us. Every other t391 cycle we sentout a LINK INTEGRITY VERIFICATION ENQUIRYmessage (LIV). We expect to get a LINKINTEGRITY VERIFICATION RESPONSE back from the Fr switch before out t391 polling cycleexpires. This is a keep alive message that does no more than let us know the link between us andthe FR switch is still alive.The information provided in a FULL STATUS RESPONSE, or ASYNCHRONOUS STATUSMESSAGE basically has two parts, the FR Switch provides a DLCI number, and whether thatDLCI is in the Active or Inactive state.Active State — means that both ends of the connection (this DTE and the DTE at the other endof the WAN cloud) are speaking correctly to the FR DCE Switches in the WAN cloud. The Inactivestate means that either the local or far end DTE is either just starting up and has not completed itsinitial negotiation with the FR Switch, or there is some sort of LMI error. Data (other than LMInegotiation messages) will only be transferred when in the Active state.Invalid — the third state value is reported locally only. It is not done by polling the FR switch.This is done if the physical connection has some sort of problem. The circuit will remain in theInvalid state until negotiation with the FR DCE Switch completes successfully.
