Google Releases Fix For Chromecast Wi-Fi Crashes (zdnet.com)

An anonymous reader quotes a report from ZDNet: Google on Wednesday said it will release an update Jan. 18 to fix a bug in Cast software on Android phones that dramatically slows down WiFi networks. Reports have been circulating this week that the Google Home Max speaker can knock the TP-Link Archer C7 router offline. In a support page, Google explains a bug caused the Cast software that connects with Chromecast devices to send a large amount of network traffic routers can't handle. Google said the update will roll out via a Google Play services update. Until the update is released, Google advises users to try rebooting their Android phone, and check that their WiFi router is updated with the latest firmware. Google didn't list specific routers impacted by the bug, but reports have indicated routers from Linksys and Synology are seeing network crashes as well.

Comments

There are two bugs here.

[CptLoRes]

1. Google sending out excessive/malformed data streams. 2. A WiFi router that can be knocked offline by receiving wireless data.

Re:There are two bugs here.

[KingMotley]

#2 is a bigger problem, but realistically home routers were never designed to do those types of things. They aren't capable of doing full wirespeed packet inspection, and for 99+% of the homes this works fine at a fraction of the cost.

The obvious solution if you need to do wire speed packet inspections, have huge routing tables, and rock solid stability, then buy a router designed for business use. Unfortunately those are MUCH more expensive.

Re:There are two bugs here.

[MatthiasF]

He's talking about BitTorrent. Peer-to-peer services like it are notoriously stressful for routers.

Re:There are two bugs here.

[swillden]

#2 is a bigger problem, but realistically home routers were never designed to do those types of things. They aren't capable of doing full wirespeed packet inspection, and for 99+% of the homes this works fine at a fraction of the cost.

Huh? These are just ordinary multicast packets; the only inspection the router needs to do is to check the destination address, which they have to do with every packet they handle. It's what routers do... look at destination addresses and forward the packet on the right interface. If they can't do that at wire(less)speed, then they pretty much fail as routers. And it's not like it's difficult to handle a few hundred megabits per second with modern CPUs, even low-power ones.

Re:There are two bugs here.

[thegarbz]

Yes but the interesting part here is just how many devices are affected. The Slashdot story recently talked about TP-Link's Archer router. I'm experiencing it on a top of the line D-Link. A quick search of Reddit and some other forums find similar reports across the board, including ASUS, Apple's Airports, and ... for a proper piece of irony Google's own WiFi router.

What is happening here is that home routers aren't resistant to denial of service due to scenarios that the programmers didn't expect (DoS from inside your own network using a protocol and transmission method that is normally run at an incredibly low rate).

Re:There are two bugs here.

[deesine]

^^^ This. I've run over a dozen media TV boxes (all the name brands plus) with two different routers from VerizonFios. Chromecast would occasionally make the older router choke. Problem solved when I settled on a generic Android box, because they are the only ones able to play all formats.

Re:There are two bugs here.

[hankwang]

I assume you mean an Android HDMI dongle? How do you make that practical to use? I tried two (Android 4.x), but controlling them with a wireless mouse (no multi touch) gets really old, especially if you need to type something.

Re:There are two bugs here.

[KingMotley]

I think the disconnect here is you think that multicast packets are just simple routes and they aren't. There are many types of multicast packets, and you are probably thinking of the 224.x.x.x types, which isn't what most people use, and specifically google chromecast uses the DIAL protocol in the 239.x.x.x range (239.255.255.250 for server location discovery).

Many multicast groups function under a subscribe/unsubscribe type model, and the router has to be able to track who is subscribed to what multicast group (Bad if your router has very little memory and your network tries to spin up a ton of logical mutlicast groups...). It also means that routing for those packets won't be handled in the hardware and instead CPU routed, and quite frankly most home routers just can't handle routing a large percentage of packets through the CPU. You are quite mistaken in thinking that the CPUs in most routers are capable of "easily" routing a few hundred mbps of tiny packets. Try it, even with the latest and greatest home routers available and you'll quickly find they will get overwhelmed.

As an example, my current home router is a Asus AC-RT88U (Dual core 1.4Ghz CPU), which when I bought it was about the fastest you could find in a home router at any price. Turn on some QoS functions and it'll quickly die because the packets are being routed through the CPU. It also has 8 ports, but logically it's two 4-ports bridged via software, and if you have a large amount of data that has to go from one of the 4-port switches to the other... Again, it'll die.

And before you go on about how that router/brand sucks, I can't point at a shelf with all the big name routers on it (netgear, asus, linksys, etc) of all makes and models running stock and non-stock (tomato, dd-wrt, etc).. All of which perform worse.

So, as I stated before... Home routers just weren't designed to handle wirespeed traffic of unusual types whether it be large amounts of open TCP connections through NAT (this is what killed most routers in peer-to-peer) or having to do most of the routing through the CPU. They handle the traffic patterns that 99% of households require, and if you step outside of that, they fall flat -- quickly.

Patch is for Google Play Services

[tepples]

The summary states that the patch is for Google Play Services, an application included with most non-Amazon Android devices sold outside the China market.

Re:why is the problem with traffic?

[Anonymous Coward]

Um no. As noted in TFA it also effects Linksys which in the past couple of day released a firmware update that mitigates the wifi dropping out or otherwise at best unreliable. Since updating to that my WRT3200ACM has been behaving much better. It can go now for hours without problems. So far it's only dropped out a couple of times. Linksys did note though sparingly one of the problems was exactly as mentioned in the article. A dollar a doughnut your's has the same problem.

Testing...

[Khyber]

How the hell did they not notice a massive spike in bandwidth usage in testing?

Re:Testing...

[antdude]

Because they don't have a QA department? :P