Carrier Access SNMP Remote Mode Remote T1 Line or Payload Loopbacks, Ansi T1.403 Remote T1 LLB

Remote Mode: Remote T1 Line or Payload Loopbacks

12.7 Remote Mode: Remote T1 Line or Payload Loopbacks

In Remote mode, if the T1 line is ANSI T1.403 ESF formatted and Network Loopback detect and ESF ANSI detect both has been enabled, the two types of loopback codes the Access Bank II - SNMP can be configured to detect are Remote T1 Line and Remote Payload Loopback. The default setting in Remote mode is Remote T1 Line Loopback.

12.8 ANSI T1.403 Remote T1 LLB

In a Remote T1 Line Loopback, upon receipt of a bit-oriented loopup command message consisting of 0000111011111111 repeated at least 10 times toward the Access Bank II - SNMP in the Facility Data Link (FDL), data recovered off the T1 line is transmitted back onto that T1 span specified with no changes in bit sequence integrity, framing format or removal of BPVs. The Access Bank II - SNMP should maintain the Remote LLB when it receives a loopback retention signal of 0010101011111111 sent continuously from the far-end. The loopback retention code word should be present in the returned T1 signal. The Remote T1 LLB is released upon receipt of the bit-oriented command message consisting of 0011100011111111, repeated at least 10 time in the FDL toward the Access Bank II - SNMP. See ANSI T1.403-1995, Section 9.3.2.2-3 and Table 4.

12.8.1 ANSI T1.403 Remote Payload Loopback

In a Remote Payload loopback, upon receipt of a bit-oriented loopup command message consisting of 0001010011111111 repeated at least 10 times toward the Access Bank II - SNMP in the FDL, the payload of the received T1 signal (192 information bits of a DS1 frame) is returned with no changes in bit sequence integrity and newly generated ESF framing. The T1 Framer will correct the BPVs in the 192 bits of payload data and re-transmit the data. The FPS framing pattern, CRC-6 calculation, and the FDL bits are not looped back, but are instead, reinserted by the Framer. The remote PLB is released upon receipt of the bit-oriented command message consisting of 0011001011111111, repeated at least 10 times in the FDL.

12.9 Illustrations of Loops and Self-Tests

The following illustrations show how the loop-back tests and self-tests work. See the descriptions above for more information about specific tests.

Figure 12-1 shows how to read the illustrations that follow.

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