User Guide

Troubleshooting the Frame Relay Connection
Local Management User’s Guide 2-33
• Synchronous Polling Messages. The t391 timer for ANSI/ITU Frame Relay forms the basis for
polling between the FR switch and the FR DTE (us). We transmit a STATUS ENQUIRY every
t391 seconds (10 by default) to the FR switch. We expect a STATUS RESPONSE before we
reach our next t391 polling cycle. The very first time we transmit a STATUS MESSAGE, and
every successive N391 times (6 by default) we send out a FULL STATUS ENQUIRY. We
expect a FULL STATUS RESPONSE, which contains information on the DLCIs the switch has
assigned to us. Every other T391 cycle we send out a LINK INTEGRITY VERIFICATION
ENQUIRY message (LIV). We expect to get a LINK INTEGRITY VERIFICATION
RESPONSE back from the Fr switch before out t391 polling cycle expires. This is a keep alive
message that does no more than let us know the link between us and the FR switch is still alive.
The information provided in a FULL STATUS RESPONSE, or ASYNCHRONOUS STATUS
MESSAGE basically has two parts, the FR Switch provides a DLCI number, and whether that
DLCI is in the Active or Inactive state.
• The Active state means that both ends of the connection (this DTE and the DTE at the other end
of the WAN cloud) are speaking correctly to the FR DCE Switches in the WAN cloud.
• The Inactive state means that either the local or far end DTE is either just starting up and has
not completed its initial negotiation with the FR Switch, or there is some sort of LMI error. Data
(other than LMI negotiation messages) will only be transferred when in the Active state.
• A third state value, Invalid, 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 the
Invalid state until negotiation with the FR DCE Switch completes successfully.
FR Error Table
This table is a standard part of RFC 2115, and provides the following information on a physical
interface per physical interface basis:
• The time of the failure: (value of Mib II sysUpTime)
• The type of failure
receiveShort: The frame was not long enough to allow demultiplexing - the address
field was incomplete, or for virtual circuits using Multiprotocol over
Frame Relay, the protocol identifier was missing or incomplete.
receiveLong: The frame exceeded maximum length configured for this interface.
illegalAddress: address field did not match configured format.