Cabletron Systems CyberSWITCH HSIM-W6, Руководство по установке

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Chapter 4: Troubleshooting
4-12 HSIM-W6 Installation Guide
Troubleshooting the Frame Relay Connection
There are three troubleshooting tools available. The first has always been available and is LM. The
second is the FR Error MIB Table, and reflects LMI or DLCI data errors. The third is new and is
available as the Mib Nav command: “fr”.
Communication with the FR switch is done through one of two methods:
Asynchronous Status Messages —
At any time the Fr Switch can send an unsolicited (no
polling from us) message to us. Each message contains information on one DLCI and one only. It
has the DLCI number and the DLCI state. We don’t respond to this message, but we do adjust what
we know about DLCIs based on this information.
Synchronous Polling Messages —
The t391 timer for the 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, which
contains information on the DLCIs the switch has assigned to us. Every other t391 cycle we sent
out a LINK INTEGRITY VERIFICATION ENQUIRYmessage (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.
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.
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 the
Invalid state until negotiation with the FR DCE Switch completes successfully.