All,
Going to be moving from 4 bonded downstreams to either 8 bonded downstream or a loadbalanced pair of 4 bonded downstreams, curious if others have done this and which method is preferred?
It has some design considerations which is why I am asking, if I do 8 bonded downstreams then for a fully populated card I need 72 downstreams and 27 upstreams (we put three in each service group), whereas if we do a load balanced pair of 4 bonded downstream then we need 72 downstreams and 54 upstreams. Licensing costs are about $25k different so its significant.
Will docsis 3 modems that only have 4 qam tuners be able to lock on to 8 downstream service group? Or will they lock on a single downstream?
> Will docsis 3 modems that only have 4 qam tuners be able to lock on to 8 downstream service group?
No. They can only lock onto a group which has equal or less number of DS channels
But I think you are mistaken in how it works.
Say you partitioned your card into 9 mac domains, each with 8 DS and 3 US
When you setup your wideband interfaces, you can have more than one in each mac domain. Like this :
create wide5/0/0:0 which contains all 8 DS (8x modems will connect here)
create wide5/0/0:1 which contains 1st 4 DS (half your 4x modems should connect here)
create wide5/0/0:2 which contains 2nd 4 DS (half your 4x modems should connect here)
So there are multiple widebands inside the same mac domain
int cable 5/0/0 would contain
8 DS
3 US
then repeat all of above for 5/0/1, 5/0/2 through to 5/0/8
And off you go! 27 US is all you need. If you start running out of US capacity then you would buy more US licences and change it to say 4 or 5 or 6 US per mac domain
If you needed more than 9 mac domains, and wanted to support 4X and 8X bonding then you can use some other tricks like described below :
On the 20x20 cards it is common to partition this up into 4 service areas, each with 4 "direct" DS (primary), plus then "span" the remaining 4 DS (secondary) across all 4 areas.
This allows each of the 4 mac domains to be setup with 1 x 8 way bonding group (4 local plus 4 spanned), plus 1 x 4 way bonding group (4 local)
The spanned 4 DS provide bursting capacity for the 8x modems each MAC domain.
I guess if each domain is flat chat then you are effectively running 5 DS per mac domain, but in real world cases the traffic will ebb and flow and thus each mac domain can burst up to full 8 DS speeds
Older 4x4 modems are happy, and newer 8x4 modems are even happier. And old D2 modems can load balance themselves across the 4 primary DS.
Typically you would then send 4 or 6 US to each mac domain (2 mac domains with 4 US, and 2 with 6 US = the 20 US from the card).
Maybe you could think about something similar with your 3G60. You dont have to span 4 DS across 9+ domains, you could make the spanning a bit smaller and mimic like 3 sets of the 20x20 config above.
Ha! hope that makes sense!