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RBK752 and compatible cable modems

mrosen
Tutor

RBK752 and compatible cable modems

I received an email from Comcast recently telling me that "latest device can't keep up with the latest speeds."

 

I guess I got upgraded from 1 Gbps service to 1.2 Gbps at some point.

 

I had purchased my DOCSIS® 3.1 Cable Modem (CM1150V) along with the Orbi RBK752 almost two years ag

 

I looked at their list of compatible devices.  First, I no longer need voice capability.  I started with the DOCSIS 3.1 Cable Modem (CM2000).  But when I look at the product page it says, Works best with RAX120, RAX200, Orbi RBK852, and future routers with 2.5 Gbps WAN ports."

 

Does that mean it won't work well with my model router?

 

Other models Comcast says are compatible with my speed are:

Motorola MB861

ARRIS S33

Motorola B12

HitronTechnologies CODA56 (I've never of this brand)

ARRIS S33v2

 

Thanks.

Message 1 of 7

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CrimpOn
Guru

Re: RBK752 and compatible cable modems


@mrosen wrote:

Oh, really?  That extra .2 Gbps isn't worth the expense?  That's good to know.


Sorry for the terse response earlier.

 

The existing CM1150V modem supports port aggregation to pass greater than 1GB to the customer router.

https://www.netgear.com/images/datasheet/networking/CableModems/CM1150V.pdf 

Page 13 of the user manual explains port aggregation:

https://www.downloads.netgear.com/files/GDC/CM1150V/CM1150V_UM_EN.pdf 

 

Port aggregation was a technique that was introduced when DOCSIS 3.1 modems became available, but consumer routers did not have Ethernet ports capable of greater than gigabit speed.

 

The RBR750 router also supports link aggregation:

https://www.netgear.com/images/datasheet/orbi/RBK752.pdf 

 

Thus, without spending any money, that extra .2GB can be available to the router, provided that you can get port aggregation to work.  (I have no experience with that feature.)

 

If you do choose to purchase the CM2000 modem, it does  not support port aggregation because it comes with a single 2.5GB Ethernet port:

https://www.netgear.com/images//datasheet/networking/CableModems/CM2000.pdf 

In this case, the RBR750 can connect only the single gigabit WAN port, and thus can achieve at most 1GB, and the additional .2GB is superfluous.  To get the additional .2GB with the new modem means you also have to purchase a new router.

 

As to "worth it", it is hard to imagine a residential customer who needs greater than a constant 1GB internet connection.

Streaming 4K video requires 25MB. So, let's assume 10 TV's constantly streaming video. (250MB)  Add in 10 people constantly hosting Zoom meetings (@ 4GB each = 40GB).  Add in another 10 people playing video games (Call of Duty @ 4.0 = 40MB)

That amounts to 250+40+40 = 330MB, leaving only a puny 670MB for "other stuff".

 

 

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Message 5 of 7

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CrimpOn
Guru

Re: RBK752 and compatible cable modems

Yes, it will work well with the RBR750 router, except that the speed will be limited to 1GB because the RBR750 has only a 1GB WAN port.

 

Honestly, I see no urgent reason to change anything.

Message 2 of 7
mrosen
Tutor

Re: RBK752 and compatible cable modems

Oh, really?  That extra .2 Gbps isn't worth the expense?  That's good to know.

 

Thanks.

Message 3 of 7
plemans
Guru

Re: RBK752 and compatible cable modems

yes the .2 isn't worth the expense. Most devices aren't going to max out a 1 gig connection. Especially wireless devices.  And most websites/servers aren't going to even be able to saturate it either. 

Its more of a marketing gimmick 

Message 4 of 7
CrimpOn
Guru

Re: RBK752 and compatible cable modems


@mrosen wrote:

Oh, really?  That extra .2 Gbps isn't worth the expense?  That's good to know.


Sorry for the terse response earlier.

 

The existing CM1150V modem supports port aggregation to pass greater than 1GB to the customer router.

https://www.netgear.com/images/datasheet/networking/CableModems/CM1150V.pdf 

Page 13 of the user manual explains port aggregation:

https://www.downloads.netgear.com/files/GDC/CM1150V/CM1150V_UM_EN.pdf 

 

Port aggregation was a technique that was introduced when DOCSIS 3.1 modems became available, but consumer routers did not have Ethernet ports capable of greater than gigabit speed.

 

The RBR750 router also supports link aggregation:

https://www.netgear.com/images/datasheet/orbi/RBK752.pdf 

 

Thus, without spending any money, that extra .2GB can be available to the router, provided that you can get port aggregation to work.  (I have no experience with that feature.)

 

If you do choose to purchase the CM2000 modem, it does  not support port aggregation because it comes with a single 2.5GB Ethernet port:

https://www.netgear.com/images//datasheet/networking/CableModems/CM2000.pdf 

In this case, the RBR750 can connect only the single gigabit WAN port, and thus can achieve at most 1GB, and the additional .2GB is superfluous.  To get the additional .2GB with the new modem means you also have to purchase a new router.

 

As to "worth it", it is hard to imagine a residential customer who needs greater than a constant 1GB internet connection.

Streaming 4K video requires 25MB. So, let's assume 10 TV's constantly streaming video. (250MB)  Add in 10 people constantly hosting Zoom meetings (@ 4GB each = 40GB).  Add in another 10 people playing video games (Call of Duty @ 4.0 = 40MB)

That amounts to 250+40+40 = 330MB, leaving only a puny 670MB for "other stuff".

 

 

Message 5 of 7
mrosen
Tutor

Re: RBK752 and compatible cable modems

Thanks!

 

I never really understood how to get the port aggregation to work.  I'll have to look into that.

Message 6 of 7
plemans
Guru

Re: RBK752 and compatible cable modems

Just to chime in on port aggregation, I wouldn't use it. For business gear its been pretty stable but most of the consumer gear I've used, has had issues. Both in stability and speed. And I've tried several different modems from arris/netgear and routers from both. My best combination for stability was using a netgear cm1100 and an Arris AX11000 (w31). 

Still wasn't that great and wasn't worth the headache for the extra .2 that I had so I disabled it. 

Message 7 of 7
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