Cisco Cisco WT2750 Multipoint Broadband Wireless System 信息指南
Q. What if the SU cannot get beyond the ranging_1_state?
A. The initial−ranging−offset can be set incorrectly. See the above question and answer. The
other possibility is that something is wrong with the upstream signal. Check that the upstream
frequency is set correctly. Make sure that ALC is turned on. This is the default mode, but you
can also set the transmit gain manually, which disables ALC. In general, you must not disable
the ALC. In order to insure that ALC is turned on, type the no radio diag transmit−gain
command from the interface prompt.
other possibility is that something is wrong with the upstream signal. Check that the upstream
frequency is set correctly. Make sure that ALC is turned on. This is the default mode, but you
can also set the transmit gain manually, which disables ALC. In general, you must not disable
the ALC. In order to insure that ALC is turned on, type the no radio diag transmit−gain
command from the interface prompt.
Q. What if the SU cannot get beyond the ranging_2_state?
A. This probably means that the HE sees either too much or too little power from the SU, or
that the signal from the subscriber is too poor to demodulate consistently. There are messages
that tell you to what the transmit gain is being set. Here is a command, which means that the
SU was told to reduce the gain by 3 dB [−3 db], and so the SU set the IF gain to −4 dB and
the RF gain to 0 dB:
that the signal from the subscriber is too poor to demodulate consistently. There are messages
that tell you to what the transmit gain is being set. Here is a command, which means that the
SU was told to reduce the gain by 3 dB [−3 db], and so the SU set the IF gain to −4 dB and
the RF gain to 0 dB:
10:54:26: SU RFSM: DSPMSG_TX_POWER_ADJ [−3 db], IF[−4 db], RF[00 db]
In order to see the legal range of transmit gain settings, type these commands from the exec
prompt:
prompt:
show cont r1/0 rf
show cont r1/0 if
These commands show a lot of information about the IF and RF cards, and one of the fields
they display is the range of the Time Zone (TX) variable gain. If the subscriber only uses
gains near the bottom of the range, probably the HE receives too much power. Switch to a
lower power ODU, align the antenna differently, or put an attenuator between the ODU and
the antenna.
they display is the range of the Time Zone (TX) variable gain. If the subscriber only uses
gains near the bottom of the range, probably the HE receives too much power. Switch to a
lower power ODU, align the antenna differently, or put an attenuator between the ODU and
the antenna.
On the other hand, if the SU is set to full gain and the HE continues to instruct the SU to
increase the power, this is an indication that the HE does not receive enough power. Check to
what value the RF receive power of the HE is set, and check the alignment of the antenna. A
higher gain antenna can help. Alternatively, move the antenna around, or mount it higher.
increase the power, this is an indication that the HE does not receive enough power. Check to
what value the RF receive power of the HE is set, and check the alignment of the antenna. A
higher gain antenna can help. Alternatively, move the antenna around, or mount it higher.
Q. What if the SU gets to the dhcp_state but never gets an IP address?
A. If you see the dhcp_state message and never see an IP address get assigned to the SU, this
generally points to incorrect configuration of the DHCP server, or the lack of an IP path to the
DHCP server. Verify the configuration of the DHCP server and if you run an external DHCP
server, verify that the correct radio helper−address command is configured under the radio
interface through the show running command.
generally points to incorrect configuration of the DHCP server, or the lack of an IP path to the
DHCP server. Verify the configuration of the DHCP server and if you run an external DHCP
server, verify that the correct radio helper−address command is configured under the radio
interface through the show running command.
Q. What if the SU gets to dhcp_state, receives an IP address but fails on
other parameters?
other parameters?
A. Other parameters that the SU requires are the TFTP server address, the Time of Day
(TOD) server address, the Time Zone (TX) offset value, and the DHCP config file name (also
called the DOCSIS config file). These parameters must all be present in the DHCP response
from the DHCP server.
(TOD) server address, the Time Zone (TX) offset value, and the DHCP config file name (also
called the DOCSIS config file). These parameters must all be present in the DHCP response
from the DHCP server.