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Modem Power-on System Test (POST).
If LED remains blinking, faulty modem.
Modem scanning downstream frequencies.
Modem ranging upstream.
Downstream and Upstream acquired. Modem
processing for DHCP, TFTP, and TOD.
Modem operational. Activity light blinks
when transmitting or receiving data.
“Standby” switch enabled. Modem successfully
completed boot sequence and all LED’s
blink off, except “Standby”.
Modem powered off.
SURFboard SB4101 Cable Modem LED Status
Power on
Downstream Scan
Upstream Range
Network Connect
Network Activity
Standby
Power off
E
F
G
D
C
B
A
Notes:
TM
Notes:
R
R
483826-001-99 Rev C
P
OWER
R
ECEIVE
A
CTIVITY
S
TANDBY
S
END
O
NLINE
S
B
4
101
S
U
R
F
b
o
a
r
d
C
a
b
l
e
M
o
d
e
m
®
Power
Receive
Send
Online
Activity
Standby
SURFboard SB4101 Cable Modem
A
B
C
D
E
F
G
On =
Off =
Flashing =
J-5362-601-5K
Next 6 MHz
scan
Initialization
complete
(note E)
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
No
No
No
No
Yes
Modem power-on
POST
(Note A)
Complete
registration with
CMTS
SB4101
standby
switch is
enabled
Log error
and continue
Modem begins
scanning for
DOCSIS
downstream
(Note B)
Using TFTP
server and
filename from
DHCP, download
the TFTP
configuration file
Establish time of
day using server
IP provided by
DHCP
Hardware failure,
replace modem
Modem begins
ranging power
at 25 dBmV
moving up in
6 dBmV steps
to maximum of
60 dBmV
and then
drops down to
8 dBmV and
starts over.
Range is
attempted 3
times.
Did POST
pass?
Standby
LED on
(note F)
CM assigned
IP address?
Ranging
successful?
DOCSIS sync?
64 or 256 QAM?
BLP
enabled?
CM receive
config file?
Did CM get
TOD?
Using UCD
information begin
ranging power at
specified upstream
frequency
(note C)
,
RF link is
established.
Modem will now
issue a DHCP
broadcast
(note D)
Key
Authorization
/