H3C Technologies H3C SR8800 - Manual (Page 62)

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Table 2 Parameter description for frame relay protocol
Router role Parameter description Value range Default value
DTE
PVC status enquiry counter (N391) 1 to 255 6
Error threshold (N392) 1 to 10 3
Event counter (N393) 1 to 10 4
User side polling timer (T391), the value 0
indicates that the LMI protocol is disabled 0 to 32767
(in seconds) 10
(in seconds)
DCE
Error threshold (N392) 1 to 10 3
Event counter (N393) 1 to 10 4
Network side polling timer (T392)
5 to 30
(in seconds) 15
(in seconds)
These parameters are stipulated by Q.933 Appendix A, and their meanings are described in the
following sections.
Description on parameters related to DTE
The following parameters are related to DTE:
• N391—Sets the full status polling interval. DTE sends Status-Enquiry messages at a certain interval
(determined by T391). Status-Enquiry messages fall into the following types: link integrity
verification messages and full link status enquiry messages. N391 defines that the ratio of sent link
integrity verification messages to sent full link status enquiry messages equals (N391–1):1.
• N392—Sets the threshold for errors among the observed events.
• N393—Sets the total of observed events.
• T391—Sets the interval for a DTE to send State-Enquiry messages.
A DTE sends Status-Enquiry messages at a certain interval to query the link status. The DCE responds with
a Status response message on receiving the message. If the DTE fails to receive any response within a
specified period, it will record this error. If the number of errors exceeds a certain error threshold, DTE will
regard the physical channel and all virtual circuits unavailable (N392 and N393 together define the
error threshold). If the number of errors reaches N392 among the N393 Status-Enquiry messages sent by
DTE, DTE will consider that the number of errors has reached the threshold.
NOTE:
Status-Enquiry messages fall into the following types: link integrity verification messages and full link status
enquiry messages. The full link status enquiry messages query PVC status in addition to link integrity.
Description on parameters related to DCE
The following parameters are related to DCE:
• N392 and N393—These two parameters have similar meanings to those related to DTE. However,
DCE requires that the fixed time interval for DTE sending a Status-Enquiry message should be
determined by T392, and DTE requires that this interval should be determined by T391. If DCE does
not receive the Status-Enquiry message from DTE within a period determined by T392, an error
recorder is created.
• T392—Sets the time variable, which defines the maximum time that DCE waits for a Status-Enquiry
message and should be larger than the value of T391.