Erlang/OTP and SDL

Vance Shipley <>
Thu Sep 16 22:28:57 CEST 2004


It is not suprising that Matthias' Erlang implementation of MTP2 did
not perform well.  This is work that is normally done in hardware.

The MTP2 protocol should be implemented in silicon the same way
HDLC is.  In MTP2 there is no idle time, FISUs (Fill-In Signal Units)
are sent continuously in the absence of payload.  Each FISU has an
FCS (Frame Check Sequence) which requires a CRC-16 calculation to be
done.  You will find that in any commercial product the CRC work and
the handling of FISUs is done in hardware.  This is the same as in 
HDLC where the flag delimiting, bit stuffing and CRC work are done in

For these reasons MTP2 and HDLC are not appropriately handled in Erlang.
Everything above that is quite practical to implement in Erlang.  But
I may be biased because I implement protocols in Erlang.


Vance Shipley
Motivity Telecom Inc.
+1 519 240 3684

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