Hacker News new | ask | show | jobs
by windexh8er 4098 days ago
What the author doesn't realize is he's doubled nothing. DOCCIS networks are shared mediums. That means you have to double bandwidth by increasing the number of channels you have. Newer DOCCIS modema are already bonding channels today. Most commonly 4 channel bond on the downstream and 2 on the up. By connecting to the cable modem twice, via two different routes, does nothing to change the available bandwidth available to the users behind the CPE (cable modem). As some have stated you could do this against your neighbors modem to share more channels on the cable media, however your neighbor is on the same HFC node and sharing the same available bandwidth to how many other users are connected to that node. You may get a few extra megabit but its the latency that will make that portion of the link "slower" so you really won't improve things much, if at all.

The best way to improve consumer Internet connection is to get a fast router that can route fast in hardware. I'm always amazed people think a SOHO device doing WiFi, NAT, DHCP, DNS, etc. on gimped hardware is "fast". The majority of time it's not and real improvements can be realized with dedicates hardware. Meaning that until you split service off from routing using cheap, consumer SOHO gear, will most always be the bottleneck.

5 comments

His connection is probably throttled. This essentially doubles his throttled bandwidth.
Having worked with deployment of these networks (DOCCIS 3) for a Comcast subsidiary I can tell you this is not true. If you have 10Mb the non-guest network is prioritized. But you cannot use more than 10Mbit between the two. As stated, the author has doubled nothing.
From the XFINITY WiFi FAQ[1]:

> Does the new Home Hotspot impact my Internet speeds or data usage?

> The broadband connection to your home will be unaffected by the new feature.

Doesn't sound consistent with the prioritization claim since prioritization still implies the speed may be affected by the guest network. If you're right, then that's kind of a bold (misleading) thing for Comcast to say in their FAQ.

If the author is doing this by using the neighbor's WiFi (as mentioned in some other comments), then I don't see how this has anything to do with XFINITY WiFi specifically, or any loopholes - stealing bandwidth from a neighbor could be done (in theory) with any open/accessible WiFi connection of a neighbor.

[1] https://wifi.comcast.com/faqs.php

You can if you use the neighbor's guest connection.
The author doesn't implicitly state this, only that his neighbor also has it. You're still failing to understand that a $50 SOHO router has a cheap transceiver and getting to your neighbors guest network is far more latent and prone to dropped packets and errors due to the distance. Also the embedded transceiver in the cable modem is competing with a lot of local RF from the cable modem.

Again, he's not doubling his bandwidth based on the above and a whole host of other reasons beyond these.

For those who try I'd say post true bandwitdh and latency test comparisons using multiple sessions that are shown using both links. Its actually pretty funny to me, having been in network engineering for well over a decade, that people are so passionate that they're sticking it to Comcast and "doubling" bandwidth with nothing to back it up. But, whatever floats your boat.

If you read carefully, I wrote "You can", not "(S)he has"; I was saying you can use more than 10Mbit, not that the bandwidth has doubled.
He is using the neighbor's guest hotspot not his own.
Considering that comcast sells up 505 Mbit/s connections your 10Mb claim is demonstrably false.

DOCSIS (not DOCCIS) can do a Gb/s, and that's just to one modem, not the neighborhood as a whole.

The author is doing this against his neighbour's modem.

He isn't connecting to the same modem twice.

You seem to be dripping misplaced condescension all over the floor - would you like me to fetch a mop?

I'd suggest you reread the article.
This is network diagram described in the article:

                                                        +----------------------+
                                                        |                      |
                                          +-----------> | Neighbor's router    |
                                          |             |                      |
  +-----------+      +------------------+ |             +----------------------+
  |           |      |                  | +                                     
  | OP's PC   +----> | Buffalo Router   |               +----------------------+
  |           |      |                  | +             |                      |
  +-----------+      +------------------+ |             | OP Comcast connection|
                                          +-----------> |                      |
                                                        +----------------------+
There are no double connections to any router.
Why don't you? From the article:

When you rent a cable modem/router combo from Comcast (as one of my nearby neighbors apparently does)

The article definitely implies that he's connecting to his neighbour's Comcast router.

As stated above even if he is doing that its implied, not a direct statement. Assume away. Also, doing this will actually make your connection worse as that connection will always be more latent.

Think of it this way. When you stream a movie from Netflix it is one TCP session. Not 5, 10, etc. So if you load balance to your neighbor your stream will be worse by default. This is not equal cost load balancing, this is a hack that isn't what it seems and there are a lot of people commenting that have, apparently, little to no knowledge about basic network fundamentals.

Try it and prove you've doubled your bandwidth. There are tens of logical reasons why this doesn't work.

Think kd it this way. When you stream a movie from Netflix it is one TCP session. Not 5, 10, etc. So if you load balance to your neighbor your stream will be worse by default.

Like others have pointed out, Linux doesn't load balance a single connection over multiple WANs, so as long as the Netflix stream gets on the best link, it'll be better since it'll have to compete with fewer connections (since some will be routed over the other link).

Actually it won't. Think of it this way...

4 lane highway vs 1 lane dirt road. While combining the two makes the number of paths greater the paths themselves are not equal (my equal cost load balancing remark). So, if the router is not taking link cost into account, which it is not, you'll actually have worse performance over all of your connections because the router will try to balance them equally on session start. This means that 50% of the time you start out going to your neighbors connection and fail or go slow. It's actually more advantageous to wait for a spot on the wide, fast link than it would be to take the alternate path.

If the router was taking into account link reliability and speed (overall cost) it would only give a small percentage of connections to the worse link and only if the main link was saturated from a bandwidth perspective. None of this is happening by round robin load balancing which means more of your connections are worse. This is why routing protocols that have these features exist.

Sure. So admit you were wrong first, then explain the defensible position you meant to give.

Your comments are clearly not kind or necessary, and not all of them are even true. You might wish to rethink your commenting strategy, because you're clearly smart and I would rather that your opinion not be lost entirely.

To quote:

> When you rent a cable modem/router combo from Comcast (as one of my nearby neighbors apparently does)

Is the router really a likely bottleneck? From everything I've read, it's rare for even a $40 router not to achieve 70mbps, which is more than the average connection offers.

I just bought a TP-Link TL-WR841N and it has no problem maxing out my 30mbps connection, even with some extra LAN traffic.

>I'm always amazed people think a SOHO device doing WiFi, NAT, DHCP, DNS, etc. on gimped hardware is "fast".

I'm a big fan of my TP-Link WDR4300. I can easily max out my 250/60Mbps uplink while it's also doing NAT and some light firewalling, in software. It also runs all of my IPAM (DHCP/DNS). Additionally, it also runs OpenVPN (and can do ~20Mbps of encrypted bandwidth) and a BGP session (using Quagga) over that VPN to my local hackerspace. All in a single OpenWRT device that's sub $70.

Is it equivalent in performance to a hardware router? Of course not. But these start at a few thousand dollars (even Cisco ASA and Juniper SRX class hardware does its routing in software...).

Any product recommendations?