| Attachment | Size |
|---|---|
 modem3freq.txt | 4.55 KB |
| modem4freq.txt | 4.61 KB |
I have several modems EPC3212 doesn't take 4 freq. but 3 freq. the configuration is a mix of modular card and integrated card.
The load balance configuration :
cable load-balance docsis-group 31 index 121
downstream Modular-Cable 1/0/0 rf-channel 12-14
downstream Cable5/0/3
downstream Cable5/1/3
downstream Cable6/0/4
downstream Cable6/1/3
upstream Cable5/0/3 0-3
upstream Cable6/0/4 0-3
upstream Cable6/1/3 0-3
upstream Cable5/1/3 0-3
method utilization
threshold load 50
policy pure-ds-load
init-tech-list 4
Attached the show cable modem verbose.
The CMTS is a UBR10K PRE2.
Someone can help me ?
I doubt this relates to load-balance configuration (which looks a bit weird to me having so many interfaces in the one group)
I do notice that :
* The 3 channel modem has primary DS on Mo1/0/0:12 (SPA/modular)
* The 4 channel modem has primary DS on C5/0/3 (Integrated)
There are some limitations with mixing integrated and SPA/modular channels... Primarily related to bonding groups.
I assume you have DTI server and your modular-cable channels are primary enabled? And is looks like you have 5x20 linecards?
To allow us to troubleshoot it, you will need to provide more information about your configuration. Preferably your whole running conf, or at minimum some snippets of
controller modular-cable 1/0/0
interface cable x/x/x
interface wideband-cable x/x/x:x
fiber-node x
and also, please provide a bit of an overview about how the plant is wired.
Hi,
Yes it's a mixed configuration. We have the downstream shared in the RFGW and in the MC5x20 cards.
Attached, all running config (filtered).
Unfortunately, I don't have a design of cable plant but through the Fiber-node you can figure out.
I still continue think this issue is at the load balancing level. We have some modems connect on 4freq. and other on 3freq. on the same upstream.
You only have 3-channels configured in your wideband-cable interfaces. You need to create additional logical channels with 4 channel groupings in addition to your three channel groups. I believe you just have to make sure they're staying within the same mac domain.
It was your guess at beginning but we can even configure that. Under the wideband they only propose "rf-channel", no controllers.
ubrSWD01#sh run interface Wideband-Cable1/0/0:4
Building configuration...
!
interface Wideband-Cable1/0/0:4
cable bundle 1
cable rf-channel 12 bandwidth-percent 50 remaining ratio 100
cable rf-channel 13 bandwidth-percent 50 remaining ratio 100
cable rf-channel 14 bandwidth-percent 50 remaining ratio 100
end
ubrSWD01#conf t
Enter configuration commands, one per line. End with CNTL/Z.
ubrSWD01(config)#interface Wideband-Cable1/0/0:4
ubrSWD01(config-if)#cable rf
ubrSWD01(config-if)#cable rf-channel ?
<0-23> RF channel number
And another pity thing it's we have some modem they are on 3freq. and other in 4freq. strange !!
Unfortunately you cant create bonding groups that mix integrated and SPA/modular DS
On 5x20 cards pretty much you can only create bonding groups from modular.
On 20x20 cards you can make bonding groups from integrated or SPA/modular, but cant create mixed ones.
I had a look at your configs and they seem OK
The wideband configs and the load balance configs look correct
From cards 5/0, 5/1, 6/0, 6/1 you have 6 service areas
You are sending 3 to 4 integrated downstreams plus 3 SPA/modular downstreams to each area (6 to 7 DS in total)
All downstreams are primary enabled
In each service area, the 3 SPA/modular downstreams are configured as a bonding group
As D2 and D3 modems register, the load balance is spreading the modems evenly over the 6 to 7 primary downstreams in each service area
* If a D3 modem registers on an integrated downstream, it will then want to do bonding so will also grab the 3 SPA/modular downstreams. This 4 DS in total. The integrated downstream will be used only for DOCSIS timing traffic. The 3-channel SPA/modular bonded group will carry all the data traffic.
* If a D3 modem registers on a SPA/modular downstream, it will then want to do bonding, so will grab the other 2 SPA/modular downstreams as well. This is 3 DS in total. The primary DS will carry DOCSIS timing plus data, the other 2 downstreams will carry data only.
So performance in both cases is pretty much the same. All the user traffic is carried on 3 DS, so you aren't going to notice any difference in speeds for the "4 DS" modems vs "3 DS"
Does that explain things?
Is your problem just that the 3 DS vs 4 DS was confusing? Or are you also having troubles trying to get even traffic distributions across the integrated vs SPA/modular downstreams?
I just noticed your load balance is based on utilisation, rather than number of modems. I would normally avoid this as I am not keen on modems jumping around as load ebbs and flows. I reckon balancing based on number of modems is good enough and provides a decent load spread in most cases.
If you are having problems with trying to even out the utilisation on the various DS, there are some knobs you can tweak that do tricks like forcing all D3 modems onto the bonded DS and forcing all D2 modems onto the non-bonded.
Thanks for your explanation. We don't complain on performance or Load-balancing mechanism what confuse us is why we have some modems on 4freq. and other on 3freq. Why this apparently random behavior ?
Have you a guess ?
Because the primary DS is allocated randomly
If the primary DS is integrated, the D3 modem will then go and grab the 3 SPA/modular DS (4 DS in total). Timing is done on the primary, and data is done on the 3 way bonding group.
If the primary DS is SPA/modular, the D3 modem grabs the other 2 SPA/modular (3 DS in total) and does all traffic on this 3 way bonding group
How can I configure to only permit the Local DS (Line Card) to be primary channel for modems ? So the CM will ever take the primary channel on Line cards DS and 3 frequencies on RFGW.
To answer my question, is quite simple. To disable the primary capability of the modular-cable interfaces from the MAC domain we use 'no downstream modular-cable .....' under the interface cable configuration. For example, for Cable 5/0/0:
'no downstream Modular-Cable 1/0/0 rf-channel 0-2' "
Regards