HDSL4 Maintenance Modes HDSL4 for General Distribution Installation and Maintenance PracticeA-2 61223HDSL4L2-5CTable A-1. HDSL4 Loopback Control CodesType Source 1 Code 2,3 NameAbbreviated (N)(N)(N)(N)(C)(C)(C)(C)3in7 (1110000)4in7 (1111000)2in6 (110000)3in6 (111000)6in7 (1111110)5in7 (1111100)4in6 (111100)5in6 (111110)Loopback data from network toward network inthe HTU-RLoopback data from network toward network inthe HTU-CLoopback data from network toward network infirst HRELoopback data from network toward network insecond HRELoopback data from customer toward customer inHTU-CLoopback data from customer toward customer inHTU-RLoopback data from customer toward customer inH4R1Loopback data from customer toward customer inH4R2Wescom (N)(C)(N)(N)(N)(C)(C)(C)(N)(C)FF1E(1111 1111 0001 1110)3F1E(0011 1111 0001 1110)FF04(1111 1111 0000 0100)FF06(1111 1111 0000 0110)FF08(1111 1111 0000 1000)3F04(0011 1111 0000 0100)3F06(0011 1111 0000 0110)3F08(0011 1111 0000 1000)FF02(1111 1111 0000 0010)3F02(0011 1111 0000 0010)Loopback data from network toward network atHTU-CLoopback data from customer toward customer atHTU-CLoopback data from network toward network atH4R1Loopback data from network toward network atH4R2Loopback data from network toward network atH4R3Loopback data from customer toward customer atH4R1Loopback data from customer toward customer atH4R2Loopback data from customer toward customer atH4R3Loopback data from network toward network atHTU-RLoopback data from customer toward customer atHTU-R1. The Source column indicates which side of the interface the control codes are sent from. For example, an (N)indicates a network sourced code while a (C) indicates a customer sourced code.2. All codes are in-band unless labeled ESF-DL.3. All codes listed above must be sent for a minimum of 5 seconds to be detected and acted upon.
