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2 In the tree menu, select DTI Config. 
 
3 In the Port Mode drop-down box, select desired port mode (for DTI server 
redundancy). 
Note: For proper interoperation with the Cisco uBR10K, the correct setting for 
Port Mode is Auto Non Revert. 
4 In the Primary Port drop-down box, select Primary Port. 
Note: For proper interoperation with the Cisco uBR10K, the correct setting for 
Primary Port is Port 1. 
Note: Connection to the DTI Server can be verified using the DTI monitoring 
capability described in the next section.  
5 Configure DTI Offset by entering the desired offset value in the row coincident 
with the desired carrier.  (Units are DOCSIS ticks/64, which are the same units as 
the timing offset value calculated by the CMTS.) 
Note: Calibration of the DTI Offset is typically necessary when RFGW-1-D 
carriers are added to existing service groups as additional primary channel 
capacity (i.e. to implement MxN mac-domains, where M>1).  In such service 
groups, it is desirable that the CMTS load-balance cable modems among M 
primary channels.  Using load-balancing, the CMTS has the ability to move cable 
modems among various DS primaries (statically or dynamically) when one or 
another primary channel becomes too heavily loaded.  To implement load-
balancing, it will likely be necessary to add DTI Offset values to RFGW-1-D 
carriers so that DTI timestamp values embedded in DOCSIS SYNC messages on 
these carriers are offset to match those carried on local 5x20 downstreams in the 
same mac-domain.  
						

							 
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Generally, a service group will first be implemented using a single existing 
downstream primary from the CMTS RF linecard (i.e. the 5x20 linecard).  When 
cable modems come online using the local 5x20 primary downstream, they will 
exhibit a timing offset value that is indicative of processing delays in the 5x20 
and other characteristics of the physical plant (i.e. length of cables, temperatures, 
etc.).  Incidentally, the processing delays in the 5x20 linecard are fixed - the user 
cannot add offsets to them.  Therefore, the timing offset from the local 5x20 
primary becomes the benchmark timing offset for the service group. 
Timing offsets are critical because they are the mechanism by which the CMTS 
communicates the system time to cable modems.  Cable modems need to know 
the system time so that they will only transmit in the upstream during specified 
timeslots (so that collisions are avoided on the shared upstream medium). 
As a service group grows, operators may choose to add primary downstream 
capacity to improve the service level of the mac-domain (thus creating MxN 
domains).  Primary downstream capacity can be added using additional 5x20 
carriers, or, can be added using the M-CMTS architecture with one or more 
eQAM channels. 
If the operator chooses to add primary downstreams from an eQAM, he or she 
will discover that the eQAMs own internal processing delays contribute to result 
in timing offsets (for cable modems that register online on eQAM primaries) that 
are different than the same cable modems that previously registered online on 
the local 5x20 primary.  Therefore, eQAMs must implement a feature for 
offsetting the value of the DTI timestamp to calibrate eQAM primaries to match 
local 5x20 primaries in the service group.  All eQAM primaries must be 
manually calibrated. 
Generically, the calibration process to implement load-balancing in a mac-
domain occurs as follows: 
– Allow a test group of cable modems to register online on a benchmark 
local 5x20 primary downstream channel. 
– Using the show cable modem command at the CMTS command line, 
record the average Timing Offset for all modems in the group. 
– Add a primary downstream channel to an eQAM carrier in the service 
group.  Allow the same group of cable modems to register online on it, so 
that the operator can record the difference in the average Timing Offset 
for the group. 
– Manually calibrate out the timing offset difference using the DTI Offset 
feature of the eQAM.   
– Finally, load-balancing can be configured and enabled for the service 
group. 
6 Click Apply. 
7 Click Save. 
 
  
						

							 
 
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Status Monitoring 
Introduction 
This section provides information for status monitoring for DOCSIS compliant M-
CMTS operation. 
The RF Gateway 1 provides utilities for monitoring: 
 Input streams (i.e., stream activity, input bitrate)  
 Output streams (i.e., per carrier stream mapping, provisioned bitrate)  
 Data specific monitoring (i.e., DOCSIS sync presence) 
 DTI server connectivity and status  
Monitoring 
To View Input Monitoring 
1 Navigate to the Monitor page. 
2 In the tree menu, select the Input/GbE port.  
						

							 
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Result: Input monitoring is shown for each GbE port. 
  
						

							 
 
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To View Output Monitoring 
1 Navigate to the Monitor page. 
2 In the tree menu, select the Output/Card/RF Port. 
Result: Output monitoring is shown for each QAM Card. 
  
						

							 
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To View Data Monitoring 
1 Navigate to the Monitor page. 
2 In the tree menu, select Data. 
Result: Data monitoring is revealed for each GbE port. 
  
						

							 
 
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To View Input Details 
Additional input information (for the output stream) can be retrieved by pressing 
the Input/Details button on the output monitoring screen. 
Result: The following screen is displayed. 
  
						

							 
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To View DTI Monitoring 
1 Navigate to the Monitor page. 
2 In the tree menu, select DTI. 
Result: DTI monitoring is shown for each DTI server port. 
 
Note: DTI timestamp increments (updated ~5s) can be displayed using the Refresh 
button in the top right-hand corner of the page. 
To View Tunnel Details 
1 Navigate to the Monitor page. 
2 In the tree menu, navigate to DEPI details and select tunnels 
Result: DEPI tunnels are shown for each GbE port. 
  
						

							 
 
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Note: The session Button would display the list of sessions pertaining to each tunnel. 
The statistics button would display the statistics for the sessions associated with each 
tunnel. 
To View Session Details 
1 Navigate to the Monitor page. 
2 In the tree menu, navigate to DEPI details and select Sessions 
Result: DEPI sessions is shown for QAM channel. 
 
Note: The statistics button would display the statistics for this session. 
To View DEPI QAM Statistics Details 
1 Navigate to the Monitor page. 
2 In the tree menu, navigate to DEPI details and select statistics. 
Result: DEPI statistics is shown for each QAM channel. 
 
Note: The statistics button displays statistics for this session.