Application Scenarios - HP MSR Router Series Wan Access Configuration Manual

Device
role
How LMI works
LMI works in the following process:
1. When a DTE physically goes up, it sends a full status enquiry message to a DCE to request the
virtual circuit status. At the same time, the T391 timer and the V391 counter start. The T391 timer
specifies the polling interval at which the DTE sends status enquiry messages.
When V391<N391, the DTE sends a link integrity verification message and requests only the
link integrity.
When V391=N391, the following events occur:
−
−
2. When the DCE receives a request, the DCE sends a status message that carries the status requested
by the DTE. At the same time, the DCE starts the T392 timer and waits for the next status enquiry
message. If the DCE has not received status enquiry messages when the T392 timer expires, the
DCE records the error and increases the error count by one. If the number of errors exceeds N392
among N393 events, the DCE considers the physical link and all virtual circuits unavailable and
will not use them to forward packets.
3. When the DTE receives a reply, the DTE updates the link status and PVC status. If the DTE has not
received status messages when the T391 timer expires, the DTE records the error and increases the
error count by one. If the number of errors exceeds N392 among N393 events, the DTE considers
that the physical link and all virtual circuits unavailable and will not use them to forward packets.

Application scenarios

Typically, Frame Relay is used for Frame Relay access. Frame Relay access encapsulates upper-layer
packets on a user device by using Frame Relay and connects the user device to a Frame Relay network.
You can use Frame Relay to construct a public or private network as shown in
direct connections between data devices as shown in
Value
Timer/counter
range
Keepalive (polling
verification) timer 5 to 30
(T392)
V391 is reset to 0.
The DTE sends a full status enquiry message to request not only the link integrity but also the
status of all PVCs.
Default
Description
value
Sets the interval (in seconds) for receiving a
status enquiry message. If a DCE has not
15
received any status enquiry messages when the
timer expires, an error is recorded.
Figure 73.
234
Figure 72, and construct