Monday, August 18, 2008

Reusing OLD DCE-3 for Lab serials

For my lab, i've finished the DCE-female serial cables. I think to buy another 3, but first i tryed to reuse-recycle old Teleco's DCE-3.
Italian Telecom always leaves by customers the dismissed line's equipment, specifically the old 2Mbps DCE-3 modems.
During the years we have collected about 15 Old Dce-3s... so i tryed with the most "new" and used the following models:
Teleco TD 604T Modem DCE-3
Teleco TD 603T Modem DCE-3

On Teleco's site there is an Italian/English documentation page with the command reference and the "dedicated" terminal software for configuration ( HERE for TD 604T model, but 603T is the same).

For a DCE-3 back-to-back connection i used:
2 x DCE-3 TD 603T
2 x Rj11 to Microcoax Adapters (so cossing Rx with TX is more simple, see "accessories" on Teleco's site)
2 x Microcoax cables (old cables for dce to line connection)
2 x V.36 male to V.35 Female adapters (see "accessories" too)
2 x V35 male <-> DB60 male cables (for Dce to router connection)
1 x Cisco Console cable
2 x DB9 Adapters for Cisco Console Cable
1 x Serial DB9 male - male "gender changer" adapter, DCE-3 ACD port is female, Db9 adapter is female...

When you connect on ACD (console) on DCE-3 you can use the Telco terminal software or another terminal emulator (parameters: baud rate=600, data bits=7, parity=Even, stop bits=1, Flow control=XON/XOFF ) , you must use the following commands for bringin'up your "line":

  • AT&Z0 <-- Resets to default configuration, useful before other commands, resets the DCE-3
  • ATF31 <-- sets line speed: 31 channels x 64k bps (don't try to use all 32 channels if you don't want crc errors on router's interface!)
  • AT&N0 <-- "e" bit CRC CCITT line side
  • AT&N7 <-- "e" bit CRC CCITT user side
  • ATU2 <-- bit 4 TS0B line side report loop 3C
  • ATV1 <-- bit 5 TS0B line side fixed to 1
  • ATX0 <-- bit 6 TS0B line side fixed to 0
  • ATY3 <-- bit 7 TS0B line side used for HDLC
  • ATD1 <-- bit 8 TS0B line side fixed to 1
  • AT&L0 <-- User interface X/V active
  • AT&I1 <-- V.13 disabled
  • AT&K1 <-- V.38 disabled
  • AT&R0 <-- C105 forced to ON
  • AT&C0 <-- C107 forced to ON
  • AT&S1 <-- C140 disabled
  • AT&P1 <-- C141 disabled
  • AT&B0 <-- DCE-3 connected to MUX-F
Useful commands also:
  • AT*C <-- List of current configuration end errors
  • AT&W <-- writes configuration to Dce's nvram (DON'T FORGET IT!)

Use the same configuration on both DCE-3, connect serial DTE cables to routers and... that's all with 3 simple commands you
-saved to buy new serial DCE cables
-recycled/reused trash Dce-3
-saved some quantity of CO2 (don't know how much ;-) )

NOTE: this is a theorical example only, used for examining the possibility of a communication equipment. It's provided "as-is" without any warranty. Don't try this lab on DCE's that are property of Telco ... they aren't your own! ;-)))

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