[asterisk-users] MDL-ERROR

[jg]

I have 2 ISDN BRI boxes, each with 4 spans, where the first one is configured as CPE, the second 
one as NET(so I don't need real lines for developing and testing).

Once in a while I do see the following libpri error messages simultaneously on both boxes:

PRI Span: 1 TEI=0 MDL-ERROR (A): Got supervisory frame with F=1 in state 7(Multi-frame established)
PRI Span: 2 TEI=0 MDL-ERROR (A): Got supervisory frame with F=1 in state 7(Multi-frame established)
PRI Span: 2 TEI=0 MDL-ERROR (A): Got supervisory frame with F=1 in state 7(Multi-frame established)
PRI Span: 4 TEI=0 MDL-ERROR (A): Got supervisory frame with F=1 in state 7(Multi-frame established)
PRI Span: 2 TEI=0 MDL-ERROR (A): Got supervisory frame with F=1 in state 7(Multi-frame established)
PRI Span: 4 TEI=0 MDL-ERROR (A): Got supervisory frame with F=1 in state 7(Multi-frame established)
PRI Span: 2 TEI=0 MDL-ERROR (A): Got supervisory frame with F=1 in state 7(Multi-frame established)
PRI Span: 4 TEI=0 MDL-ERROR (A): Got supervisory frame with F=1 in state 7(Multi-frame established)
PRI Span: 4 TEI=0 MDL-ERROR (A): Got supervisory frame with F=1 in state 7(Multi-frame established)
PRI Span: 4 TEI=0 MDL-ERROR (A): Got supervisory frame with F=1 in state 7(Multi-frame established)
PRI Span: 4 TEI=0 MDL-ERROR (A): Got supervisory frame with F=1 in state 7(Multi-frame established)
PRI Span: 4 TEI=0 MDL-ERROR (A): Got supervisory frame with F=1 in state 7(Multi-frame established)
...
PRI Span: 4 TEI=0 MDL-ERROR (A): Got supervisory frame with F=1 in state 7(Multi-frame established)

It does not seem to be a severe error, because everything seems to work. I have not yet figured 
out how to produce these error messages reliably. They seem to appear after booting both 
machines before any calls have been made.

Does anybody know what to do with these messages?

The BRI cards are 100% ok and I have never seen these messages when connected to a public circuit.

jg