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Downstream Bonding 8 channel

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Downstream Bonding 8 channel

So we have docsis 3 working, I have 8 contiguous channels, and another 4 non contiguous.
At one location we placed a SB6141 it came up in full channel bonding, we replaced it with a SBG6580 and no channel bonding.
Around the system sometimes we get channel bonding, sometimes we don't, and sometimes when I look at the detail the modem says Wideband Capable : N

Primary Downstream : In8/1/0:0 (RfId : 2592)
Wideband Capable : N
RCP Index : 0
RCP ID : 00 10 00 00 08
Downstream Channel DCID RF Channel : 145 8/1/0:0
UDC Enabled : N
Extended Upstream Transmit Power : 0dB
Multi-Transmit Channel Mode : N
Upstream Channel : US1
Ranging Status : sta
Upstream Power (dBmV) : 46.80
Upstream SNR (dB) : 34.12
Upstream Data SNR (dB) : --
Received Power (dBmV) : 1.00
Timing Offset (97.6 ns): 1547
Initial Timing Offset : 1547
Rng Timing Adj Moving Avg(0.381 ns): -192
Rng Timing Adj Lt Moving Avg : -217
Rng Timing Adj Minimum : -256
Rng Timing Adj Maximum : 0
Pre-EQ Good : 42803
Pre-EQ Scaled : 3150
Pre-EQ Impulse : 272
Pre-EQ Direct Loads : 233
Good Codewords rx : 6286943
Corrected Codewords rx : 477042
Uncorrectable Codewords rx : 33337
Phy Operating Mode : atdma
sysDescr : TWC AWG Cable Modem: <>
Downstream Power : 2.60 dBmV (SNR = 40.90 dB)
MAC Version : DOC2.0
QoS Provisioned Mode : DOC1.1
Enable DOCSIS2.0 Mode : Y

Why do they bond or not bond, how can I research the reason?

Block of 8, lets call them

So you have:
Block of 8, lets call them CH1-8
Block of 4, lets call them CH9-12

Its a tricky combination.

There may be dramas, if you are trying to do 8way bonding with 8x4 modems.
8x4 modems generally want their DS channels to be consecutive.
So if you try to bond say CH1-4 with CH9-12, the modem probably wont work.
(Newer modems like 16x4, 24x8, 32x8 dont have these same restrictions, they can work with channels spread any pattern)


I reckon your best/safest bet would be to NOT create any 8 way DS bonding groups

Instead create 3 x 4way groups

Option 1)

interface wide 5/0/0:0

interface wide 5/0/1:0

interface wide 5/0/2:0

Option 2)

interface wide 5/0/0:0

interface wide 5/0/0:1
controller 1 ch1-4

interface wide 5/0/0:2
controller 2 ch1-4

This way, no matter which DS the modem locks to, there will be a covering 4-way BG available.
4-way BG allows you to get up around 100Mbps downstream speed, which isn't too bad.

DOCSIS 3.0 load balance should distribute the D3 modems evenly across the 3 x BG

Even better, if you can re-arrange your channel plan further and get the all 12 DS to be consecutive, then it opens up a lot more options. Including safe 8 DS way bonding.
See option 3 here :

Tuner Types

to my knowledge, these four tuner-types are found in 8xBonding Modems:

a) 1x96MHz
b) 2x32MHz
c) 2x96MHz
d) Fullband

so essentially the smallest common demoniator is to use two 4-channel blocks within a 96MHz wide band. This ensures that a 8x Bonding group will be working with any 8x Modem.
Also with a 16 (or more) channel CMTS it is possible to create multiple 8x Bonding groups with different channel layouts. The CMTS ensures to assign a bonding group that fits to the tuner of a certain modem.