555-233-119
1298
Issue 5 October 2002
Remote Layer 3 Query (#637)
This test will query the far-end switch or terminal adapter to determine if the
signaling connection is functioning properly at Layer 3. It will select a B-channel in
the in-service or maintenance service state and send an ISDN Layer 3 SERVice
message, which requires a response from the far end (similar to performing Test
#256 on an ISDN trunk. The test will not be performed if there are no B-channels
in an appropriate ISDN service state (as when none are administered or they are
all out of service).
NOTE:
The service state can be displayed by using the status trunk <trunk
group/trunk member> or status pri-endpoint command.
As is the case with Test #256 for an ISDN trunk, a PASS only indicates that a
message was composed and sent to the far-end switch or terminal adapter. The
ISDN PRI Specification allows up to 2 minutes for a response. Check the Error
Log for ISDN-SGR (ISDN-PRI Signaling Group) errors of type 2305 for evidence
of a Remote Layer 3 Query failure.
Tests #639 and #636 check the health of the D-channels and DS1/UDS1 Interface
Circuit Packs. As shown in the figures below, Test #637 goes one step further by
checking the communication path from the processor over the TDM Bus, through
the DS1/UDS1 Interface circuit pack, and on to the far-end switch or terminal
adapter. A special ISDN message is sent to the far-end switch or terminal adapter,
which must respond within a specified amount of time. This test is designed to
ensure that the communication path between the switch and the far-end is up and
operational, and that the two endpoints can properly exchange ISDN control
messages.
See
Figure 33
for DS1 connections,
Figure 34
for UDS1 connections.
Table 312.
TEST #637 Remote Layer 3 Query
Error
Code
Test
Result
Description/Recommendation
ABORT
Internal system error
1. Retry the command at 1-minute intervals a maximum of 5 times.
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