UBR7246VXR Question?

The answer is it depends, the top number of modems a 7246vxr can support is a fixed number somewhere around 10k I believe. However, in practice you will likely never get close.

The number of customers you can put on a 7246vxr depends on the Line Cards you have in it. There are essentially 3 different types of Line Cards that can go into a 7246 vxr.

1. MCXXC or MCXXS Blades Docsis 1.x only cards --- Examples of these are MC16C and MC28C A MC16C has 1 Downstream and 6 upstreams, a MC28C has 2 Downstreams and 8 Upstreams

2 MCXXU or MCXXX Blades Docsis 1,x and 2.0 Blades --- Examples of these are MC16X and MC28U the MC16X has 1 downstream and 6 upstreams and the MC28U blade has 2 Downstreams and 8 Upstreams, the main differences between the MCXXC and MCXXU blades are: 1. the U/X blades have a built-in upconverter and an onboard processor.

3. MC88V Docsis 1.x,2.0 and 3.0 Blade -- Like the MCXXU/X blades this blade has a built in upconverter and onboard processor however it has 8 downstreams and 8 upstreams (the downstreams require at least 4 consecutive channels)

The downstream channels come in two varieties:

64QAM -- ~ 27 Mbps of throughput
256QAM -- ~ 38 Mbps of throughput

The upstreams have a bit more variety
TDMA -- ~ 5Mbps of Throughput Docsis 1.x+
ATDMA -- ~ 15Mbps+ of Throughput Docsis 2.0+

there are some others but these are the most common

In addition depending on the docsis version you are using you may have multiple down or upstreams.

So with the primer out of the way .... the amount of customers you can put on a 7246vxr depends on what linecards you put in it, what kind of bandwidth you offer and most importantly how much bandwidth your customers use.

some real world numbers

CMTS1

3 MC28U cards
1 MC16C Card

Total of 7 downstreams currently supporting 1700 customers at about 80% utilized at peak time. This site offers 1.5-6.2 megs depending on service level.

CMTS 2

2 MC28U Cards
2 MC16C Cards

Total of 7 downstreams currently supporting 1600 customers at 75% utilization at peak same speeds as above

CMTS 3

1 MC28U
1 MC28C
2 MC16C

Total of 6 downstreams supporting 1300 customers with 85% utilization at peak same speeds as above

CMTS 4
1 MC28C
2 MC16C

Total of 3 downstreams supporting 1000 customers with 65% utilization at peak

The amount of customers per downstream will depend on usage of said downstream as a general rule we try and keep ours under 250 which works well for us, in some our more rural areas we have to keep it under 200 because there is a lot more usage.

We find we have excess upstream bandwidth, but a good rule of thumb for us is <100 customers per upstream QPSK/TDMA, and <150 for ATDMA upstreams.

In our biggest area we launched internet with 1 7246vxr for 2500 customers and 50+ nodes we quickly outgrew this setup and first went to all MC28U blades then added a new 7246vxr and now we are at 4 CMTSes with a fifth to come shortly, 23 Downstream and 5500 customers. If I were launching this same setup again today I would use 1 7246VXR and 3 MC88V blades and have more capacity (24 downstreams) than I have now even without adding docsis 3.0 into the mix.

The numbers that work for me are

Docsis 1.x, 2.0

Downstream -- < 250 customers per port
Upstream -- < 100 per port in TDMA <150 per port in ATDMA

Docsis 3.0

This is new to us we are just getting into it but here is the numbers I am starting with (we are using the 7225VXR for our deployment)
Downstreams (up to 4 bonded channels per port) < 750 customers per port with 4 bonded channels
Upstreams < 150 customers per port in ATDMA Not currently bonding upstream channels at this time.

Even with a fully loaded ubr 7246vxr with 4 MC88V blades I think you would have a hard time doing 10k customers more realistically 5-6k but that would depend on what you are offering and what customers are using.

sorry for the long winded answer but there is no quick and dirty answer.