Status Displays 20-13The format of status exchanges depends on the type of link management. Annex Dframes always use DLCI 0000, and LMI frames always use DLCI 1023. Examples ofboth formats are shown below:Annex D LMI0000 Full Status Enquiry 001/000 T 1023 Full Status Enquiry 001/0000000 Full Status 001/001 R 1023 Full Status 001/001016:N 017:N 141: N 241: A0000 LIV Status Enquiry 002/001 T 1023 LIV Status Enquiry 002/0010000 LIV Status 002/002 R 1023 LIV Status 002/0020000 LIV Status Enquiry 003/002 T 1023 LIV Status Enquiry 003/0020000 LIV Status 003/003 R 1023 LIV Status 003/0030000 LIV Status Enquiry 004/003 T 1023 LIV Status Enquiry 004/0030000 LIV Status 004/004 R 1023 LIV Status 004/0040000 LIV Status Enquiry 005/004 T 1023 LIV Status Enquiry 005/0040000 LIV Status 005/005 R 1023 LIV Status 005/0050000 LIV Status Enquiry 006/005 T 1023 LIV Status Enquiry 006/0050000 LIV Status 006/006 R 1023 LIV Status 006/0060000 Full Status Enquiry 007/006 T 1023 Full Status Enquiry 007/0060000 Full Status 007/007 R 1023 Full Status 007/007016: A 017:A 141: A 241: A0000 LIV Status Enquiry 008/007 T 1023 LIV Status Enquiry 008/007The pair of 3-digit numbers at the end of each line are the send/receive sequencenumbers. For example, LIV Status Enquiry 002/001 means that the DTE receivedsequence 001 and sent sequence 002.If the timestamp is turned on, it will be displayed at the left of each line. Note that theT or R in LMI frames indicates whether the frame was transmitted or received by theport being traced.Note that in the above example the frame relay DTE port is configured for an N1Polling Count of 6, meaning that every six polling cycles the DTE will send a FullStatus Enquiry to the DCE, asking for the status of the DLCIs on the link. The intervalbetween N1 polls is governed by the frame relay port parameter T1 Link Integrity Timer.If N1 is set to 6 and T1 is set to 10, the status of DLCIs will be reported every 60seconds. If you are using DLCI backup, you may have to lower these parameters(thereby learnng the DLCI status sooner) to avoid application timeouts onswitchovers. The tradeoff on this approach is more management overhead on the link,so it is generally better to increase the applications timeout parameters.Data ExchangesData packet (Q.922 UI frame) entries include the following, reading from the left:l Timestamp, if turned on.l T or R, indicating whether the frame was transmitted or received by the portbeing traced.l Four-digit DLCI.l Identification of any of these bits that are set:u B – Backward Explicit Congestion Notification (BECN).u F – Forward Explicit Congestion Notification (FECN).u D – Discard Eligibility Indicator (DE).u C/R – Command/Response.l Four-digit packet length, starting from the frame relay Q.922 control byte.
