Verilink DIU 2130 (880-503297-001) Product Manual User Manual
Page 34
DIU 2130 Configuration
3-10
Verilink
Scramble/HDLC
The
S
p command is used to enable or disable two options, Scramble and HDLC
Invert, which are related to ones density.
Since there is no requirement for ones density on a B8ZS T1, there is never a
reason to use scramble or HDLC inversion on a B8ZS T1. If asserting one of
these functions appears to clear up a problem on a B8ZS T1 it would indicate
there is a service problem on that span which is most likely caused by some
device being set for AMI instead of B8ZS.
On the other hand, an AMI T1 does impose certain requirements for ones
density which must be met.
If you have selected 56K mode for the DIU dataports on your AMI T1, then the
density requirement has already been met and using either scramble or HDLC
inversion is superfluous.
If you are trying to bend the rules by selecting 64K mode for an AMI T1 and
using the Scramble and/or HDLC options to minimize density violations then it
should be understood that the data pattern may violate AMI standards for ones
density and the CSU may occasionally enforce the density rules. If a CSU
enforces density on a user datastream this will always cause data errors.
Verilink Tech Support does not recommend use of Scramble or HDLC on AMI
circuits.
Use of Scramble or HDLC on B8ZS circuits is superfluous.
Use of any of these options in a frame relay environment will always render the
T1 inoperative.
Scramble has nothing to do with encryption. Your data is no more or less secure
if scramble is on or off. When scramble is selected the actual DTE data for that
port is run through a mathematical algorithm (XOR by 55hex) which increases
the probability that any particular bit will be a one (represented on a T1 as a
pulse). Use of Scramble absolutely requires use of Scramble at the far end.
HDLC inversion means that all data is inverted. When the DTE sends a one the
CSU will send a zero, conversely if HDLC inversion is on all zeros are sent as
ones. If HDLC Invert is On at one end of a circuit it must be On at the other end
as well to avoid outputting inverted data to the far end DTE.
Command
Options