Application Guidelines
Ones Density Enforcement
A-6
SpectraComm IP Router Card
076R200-000
Installation and Operation Manual
Issue 2
Ones Density Enforcement
Connection to the T1 Network requires the connecting device (SC-IP) to meet pulse density
constraints. The method for adhering to the pulse density constraints is termed Ones Density
Enforcement.
The SC-IP’s Line Code option supports:
•
Alternate Mark Inversion (AMI) with no bipolar violations
•
Bipolar with 8 Zero Substitution (B8ZS) with bipolar violations
The Line Code option you choose depends primarily on the design of the T1 Network, keeping in
mind that all equipment must be compatible with AMI coding and some equipment may not be
compatible with B8ZS coding.
When optioned for B8ZS, the SC-IP replaces eight consecutive "zeros" with a sequence, including
bipolar violations, which can be detected to allow any combination of zeros and ones to be
transmitted throughout the T1 Network.
When optioned for AMI, the SC-IP automatically inserts "ones" in accordance to the configuration
as shown below. This insertion of "ones" will cause the frame relay packets to be corrupted (FCS
errors) as illustrated in and . The user should be aware of this and attempt to eliminate excessive
zeros in the transmit direction (towards the T1 Network).
Table A-5
Application with 8(N+1) Enforcement
Line Code
Format
Consecutive
Enforcement
B8ZS
xx
xx
B8ZS
AMI
Nx56K
Consecutive
None
AMI
Nx64K
Consecutive
8(N+1)
Note
The AMI line option code is not recommended for a 64kbps network rate.
T1/FT1
T1/FT1
Frame Relay
Network
SC-IP INSERTS ONES
TO ENFORCE DENSITY
CONSTRAINT
NETWORK
ORIGINATES
EXCESSIVE ZEROS
1
2
INSERTED ONES
PASS THROUGH
UNDETECTED
3
NETWORK
RECEIVES
ERRORED
PACKETS
4
SC-IP
SC-IP
