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Ethernet Port Aggregation: what is it?

Carbo

Diamond Member
Aug 6, 2000
5,225
6
81
As I upgrade my home network I'm realizing that I'm a tech dinosaur. My needs are basic: medium sized house, two laptops, two cell phones, two smart TVs, and a printer. Shopping, surfing, and emails. No heavy apps or large file transfers.
I purchased a Netgear modem, CM1100. Still undecided on a router but I'm ready to go with the RAX40. With two ports available on the modem, I was assuming my laptop is wired directly to the modem while the other port connects to the router. Then I read about something called Ethernet Port Aggregation which suggests I connect both modem ports to the router. The laptop would then be wired to the router, as well. Is this correct?
What is the advantage of this setup?
Will it make a difference in the network I described above?
The literature on the RAX40 doesn't mention that it supports ethernet port aggregation. So is it still advantageous to wire it up this way?
Sorry for all the questions. Just trying to learn and understand. Thank you.
 

VirtualLarry

No Lifer
Aug 25, 2001
52,246
7,060
126
Well, "port aggregation" / LAG / LACP generally requires, I think, support on both ends. Some recent routers will do that now, I don't know if the RX40 will. Generally, that's for connecting at faster than 1GbE, in aggregate (LAG isn't quite the same as "bonding", I don't think, and any individual communication streams through those ports will still max out at 1GbE.)

As far as connecting both the laptop, and the router, to the CableModem, Nope, don't do that. Generally, the CableModem establishes a transparent ethernet bridge to the FIRST device that connects to it. You can't normally connect two DIFFERENT devices to a CableModem, and expect it to work properly. (Unless, you have multiple static IPs - aka using a Business-oriented CableModem, OR, the "CableModem" is actually a Gateway, which is a combo CableModem AND wireless router all in one.) (*Your CM1100 is a pure CableModem, I believe.)

Normally, you need a router, connected downstream from the CableModem, to "split" (NAT sharing of the public IP address) the internet connection / WAN IP address.

Unless your internet connection is FASTER than 1GbE (and Comcast DOCSIS 3.1 Gigabit internet is, slightly, due to over-provisioning), you won't see much benefit from a LAG group / port aggregation.

I think that I might be holding out, until I can get a router with not just ONE, but TWO "multi-Gig" ethernet ports, one for both WAN as well as LAN. (2.5GbE or 5GbE, to accommodate faster internet. You know that it's eventually going to show up, at least on FIOS, I hope.)
 

KentState

Diamond Member
Oct 19, 2001
8,167
320
126
@VirtualLarry I believe when he says port aggregation, it means that the modem can support service above 1Gbe. You would need a router on the other end that can support the WAN aggregation. Some places will support up to 2Gbe internet service.

@Carbo
The dual ports are not meant to support two devices directly connecting. You will need a router on the other end to handle DHCP, wifi and anything else in your LAN.
 

mxnerd

Diamond Member
Jul 6, 2007
6,194
900
126

Carbo

Diamond Member
Aug 6, 2000
5,225
6
81
My internet is rated at 400 Mbps.
Meaning I can plug my laptop directly into the modem? Or am I better off connecting modem to router, and laptop to router?
 

KentState

Diamond Member
Oct 19, 2001
8,167
320
126
My internet is rated at 400 Mbps.
Meaning I can plug my laptop directly into the modem? Or am I better off connecting modem to router, and laptop to router?
You are better off getting a router for many reasons. I would never directly connect a personal device into a cable modem for the simple fact that there isn't a physical firewall between you and the rest of the world.
 

mxnerd

Diamond Member
Jul 6, 2007
6,194
900
126
My internet is rated at 400 Mbps.
Meaning I can plug my laptop directly into the modem? Or am I better off connecting modem to router, and laptop to router?
You can plug in any device, but it will be completely exposed without protection.
You only do that under extreme condition for troubleshooting . Always put everything behind the router.
 

ch33zw1z

Lifer
Nov 4, 2004
34,320
13,231
146
https://www.netgear.com/home/products/networking/cable-modems-routers/CM1100.aspx#

apparently that modem will do link aggregation but you will need to buy a compatible router, the RAX80

https://www.netgear.com/home/products/networking/wifi-routers/RAX80.aspx

However, the RAX40 doesn't say it supports link aggregation.

Really, this only matters if you have an ISP connection >1Gbps on the WAN

Interesting though, I didn't know Netgear was selling home/office devices with link aggregation.

edit: here's a pic of supported configs, IOW - you won't be able to run a link to a laptop/pc and a wifi router simultaneously. Two ports from the modem will only be used simultaneously if you buy a router that supports WAN LAG

1560707539391.png
 

Carbo

Diamond Member
Aug 6, 2000
5,225
6
81
Lots of good info shared. Thank you, all.
So then I am better off connecting an ethernet cable from modem to router, then router to laptop, correct?
 

Joshuaharris4712

Junior Member
Apr 25, 2020
1
0
6
I have At&t Fiber ,an a Netgear X6s which supports LA. But does my ATT modem/router also need to support this? Because I cant seen to get it to work, i get over 1300mbs connected to my isp. Only about 700mbs connected to my NIghthawk?HELP
 

JackMDS

Elite Member
Super Moderator
Oct 25, 1999
29,192
291
126
Combining Speed (Bonding). works only if the ISP specifically supports it.

If you have two independent Internet accounts with dual port Router you can divide the Bandwidth between Network computers and other Network related devices, but you can Not get a combined speed for one single device unless it is specifically supported by the ISP (there are very few ISPs that do support it).


:cool:
.
 

Genx87

Lifer
Apr 8, 2002
41,063
495
126
LAG\LACP only provide increases in aggregate bandwidths with multiple sessions. A single session will be capped at the line speed of the port. In switch to switch it will require both sides be configured. Clients can fake it by using a virtual mac address for the port group. Thus not requiring switch configuration.

As for the above poster. How were you achieving over 1Gbps connected to your ISP?
 

Fallen Kell

Diamond Member
Oct 9, 1999
5,674
254
126
Ok, the absolute best analogy I have ever seen for LAG/LACP is the following:

LAG/LACP is like adding a second lane to a road/highway. The speed limit has not changed, but you can now have two cars travel next to each other at the same time.

Think of each of your networked applications/software as a car on a road, and then you essentially understand what LAG/LACP is and isn't. It won't let something go twice as fast as before, but will let you send/recieve twice as much stuff from multiple applications at the same time.
 

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