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Conference noted::decnis

Title: DEC Network Integration Server (DECNIS)
Notice:Please read note 1 to use this conference effectively
Moderator:MARVIN::WELCH
Created:Wed Sep 18 1991
Last Modified:Thu Jun 05 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:3660
Total number of notes:15082

3533.0. "Non-standard T3 framing???" by SCASS1::DAVIES (Mark, NPB Sales, Dallas,TX) Wed Feb 05 1997 12:11

    My customer wants to connect to the Internet using T3.  He wants to use
    a DECNIS 600.  I heard somewhere that the ATM/T3 card uses a
    non-standard framing sequence, which allows a DECNIS to only talk to
    another DECNIS when using the ATM/T3 card.
    
    Is this true?
    
    Is this for T3 only?
    
    How about if you wanted to use OC-3 for a connection?
    
    Thanks,
    
    Mark
T.RTitleUserPersonal
Name		DateLines
3533.1Lots of options...MARVIN::BASSETTJohn Bassett, REO2 F/D8 830-4867Wed Feb 05 1997 12:5240
Hi Mark,
    
>>    My customer wants to connect to the Internet using T3.  He wants to use
>>    a DECNIS 600.  I heard somewhere that the ATM/T3 card uses a
>>    non-standard framing sequence, which allows a DECNIS to only talk to
>>    another DECNIS when using the ATM/T3 card.
    
>>    Is this true?

      No.

      The W631 T3 provides two options for framing format. By default it will
      use a direct cell mapping mode which allows 13 cells to be packed into
      each M-frame. This is a non-standard format but provides the highest 
      throughput on the T3 line, if the other end of the link supports this 
      mode then it is recommended. (I've seen traffic analysers which support
      this format and hopefully it's use will become more widespread).

      The T3 framing format desribed in the ATM UNI spec includes an additional
      Physical Layer Convergence Protocol (PLCP) layer. Using this format 
      only allows 12 cells per M-frame so will cost you in performance. However
      if this is the only format you can use then

      NCL> set atm connection management line <line-name> PLCP enabled

      will cause DECNIS to use the standard format.

>>    Is this for T3 only?
    
      E3 also provides various options for PLCP/framing format. The W631 supports
      G.751 without PLCP, G.751 with PLCP or G.832 (PLCP not available), so I
      hope we've got all the options covered :)

>>    How about if you wanted to use OC-3 for a connection?
    
      There is only one format for OC-3 (a direct cell mapping mode) which is 
      the format used on DECNIS.

Hope this helps,
John B.
3533.2Thanks.SCASS1::DAVIESMark, NPB Sales, Dallas,TXWed Feb 05 1997 12:596
    This is exactly what I needed.
    
    Thanks,
    
    Mark
3533.3and frame mode HSSI soonMARVIN::HIGGINSONPeter Higginson DTN 830 6293, Reading UKWed Feb 05 1997 18:3511
Mark,

Be aware that the current card uses ATM formats at both 155M and at T3/E3
rates. An HDLC (frame mode) T3 card (actually HSSI rather than DS3) is
due to go to field test soon.

Cisco (for example) has both types of card at the T3 rate, but the frame
mode is more common for T3 access to the Internet.

Peter