AppleTV 3 floods DHCP when ethernet connected

glarbl_blarbl wrote:

To me, if a networking device is ignoring a setting by orders of magnitude -- then that is a bug.

1. Orders of magnitude more in quality of requests, but still likely 0.0001% of your network bandwidth or less. This is not causing any measurable change in network performance or through put.

2. As already mentioned it is not ignoring the setting, there is some screw ball reason one of Apple's protocols (bonjour, AirPlay, HomeSharing, etc) needs to refresh this frequently. It has likely always worked this way, and there is little chance it is going to change. It does not cause any actual problem so no not a bug or anything to worry about. Especially since you can not do anything to change it.

3. As I and others have already posted if you put a packet sniffer on any network you with find a constant stream of management/over head traffic like this were devices are constantly checking this or that. It is normal and eats up so little bandwidth it does not matter.

Not sure where everyone got the impression that I thought this was affecting my bandwidth. Don't think I ever voiced that concern. I was investigating issues with my ISP connectivity and saw how much traffic the Apple TV was showing in the logs, googled it to find this thread -- and figured I'd post my logs.

I have indeed already submitted a bug report on this. No need to tell me how small these packets are a third time, thanks.

I'm seeing similar behavior with the two ATVs that I have. The Ethernet port is toggling state roughly once per minute on one ATV and about half as often on the other ATV. Each time this happens the switch has to negotiate speed, perform STP check, update ARP and MAC tables, verify VLAN (port mobility), and then move on to the layer 3 stuff like DHCP. This behavior, the intervals in particular, don't make sense, something isn't right about the routine.

09:14:51 2016: 21:39 INTERFACE(6) Data: 1/29: link DOWN

09:14:53 2016: 21:41 INTERFACE(6) Data: 1/29: link UP

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09:16:06 2016: 22:54 INTERFACE(6) Data: 1/29: link UP

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09:18:32 2016: 25:21 INTERFACE(6) Data: 1/29: link UP

09:18:56 2016: 25:44 INTERFACE(6) Data: 1/29: link DOWN

09:18:58 2016: 25:46 INTERFACE(6) Data: 1/29: link UP

09:19:42 2016: 26:31 INTERFACE(6) Data: 1/29: link DOWN

09:19:45 2016: 26:33 INTERFACE(6) Data: 1/29: link UP

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09:20:58 2016: 27:47 INTERFACE(6) Data: 1/29: link UP

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09:22:10 2016: 28:59 INTERFACE(6) Data: 1/29: link UP

09:23:21 2016: 30:10 INTERFACE(6) Data: 1/29: link DOWN

09:23:23 2016: 30:12 INTERFACE(6) Data: 1/29: link UP

09:24:34 2016: 31:22 INTERFACE(6) Data: 1/29: link DOWN

09:24:36 2016: 31:25 INTERFACE(6) Data: 1/29: link UP

09:27:15 2016: 34:03 INTERFACE(6) Data: 1/29: link DOWN

09:27:17 2016: 34:05 INTERFACE(6) Data: 1/29: link UP

09:28:27 2016: 35:16 INTERFACE(6) Data: 1/29: link DOWN

09:28:30 2016: 35:18 INTERFACE(6) Data: 1/29: link UP

09:28:51 2016: 35:39 INTERFACE(6) Data: 1/29: link DOWN

09:28:53 2016: 35:41 INTERFACE(6) Data: 1/29: link UP

09:29:41 2016: 36:30 INTERFACE(6) Data: 1/29: link DOWN

09:29:43 2016: 36:32 INTERFACE(6) Data: 1/29: link UP

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09:30:56 2016: 37:45 INTERFACE(6) Data: 1/29: link UP

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09:32:09 2016: 38:58 INTERFACE(6) Data: 1/29: link UP

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09:33:22 2016: 40:10 INTERFACE(6) Data: 1/29: link UP

09:34:32 2016: 41:21 INTERFACE(6) Data: 1/29: link DOWN

Willie Strickland wrote:

I Have a dedicated IP address on the LAN for my AppleTV 2. Have you tried that?

I've done that with fixed reserved addresses configured on my router and I'm still seeing this DHCP spam.

It's as if the AppleTV is ignoring the IP Address Lease Time (option 51). You're not supposed to renew a lease until you're at least 50% through the lease's lifetime.

Brian Cook4 wrote:

Once per minute is not a flood, if it was thousands of time per minute I would agree that is a flood and a major issue. Once a minute is nothing. If you put tcpdump on pretty much any device you will see a constant stream of seeming needless management traffic. I would guess it is related to supporting their screwed up Bonjour protocol but who knows. What ever the reason that is the way it works and it is not likely to change, and it is not hurting anything.

You're splitting hairs. The point is that it's not RFC conformant.

DHCP is a trivial protocol which has been around for a long time and it's well understood (I wrote RFC-1048 twenty-eight years ago).

There's no excuse for getting it wrong, especially not for a company the size of Apple with the resources to test this adequately and fix known (and widely reported) bugs.

Such behavior also doesn't scale well. What if you've got a DHCP server using an inefficient database representation (like a flat text file) which it has to open and read each time that it gets a request, and it's got hundreds of entries? Routers (especially CPE routers) tend to be budget boxes with a BOM of about $75 or less... and hence don't have a lot of cycles to spare beyond basic packet forwarding or filtering.

Having them do something 1440 times a day that they should be doing once a day or less is just plain broken anti-social behavior.

Mario MG wrote:

FYI, Apple TV 4 does not have this problem. I have 2 3s, and 2 4s, only the 3s exhibit this problem. The ATV 4s are way better so once we replace the problem solved. Apple is not likely to fix this on the ATV 3.

Well, it's a software issue and Apple will continue to release software for the ATV2 and 3, if they want to generate revenue from legacy users (which tend to be the "early adopters" and "true believers" that you don't want to alienate).

I don't see why they would add functionality to software releases yet not fix known (and documented) bugs... Their brand's justification for the significantly higher prices (compared to the competition occupying the same market space) has always been "you get what you pay for".

Except when you don't.

I don't see why they would add functionality to software releases yet not fix known (and documented) bugs...

A few things to keep in mind:

1) We don't know if they've been able to reproduce the issue. As I mentioned almost a year back, I have three 3rd gen ATVs, all hardwired, and none exhibit the bug. The DHCP implementation isn't brain dead but may have a bug in a particular set of circumstances. It might not even be that DHCP is the problem (see #3 below).

2) All bugs get prioritized and the reality, especially with a huge customer base, is some never rise to the point where they get fixed. As someone who has been in the trenches, I can see how other issues (including new features which promise added revenue) could take priority over this problem.

3) The one post a while back is interesting (Jan 12, 2016 from ElectronArt). If I'm reading it correctly, the link to the router or switch connected to the ATV is going down and back up again. In that is happening, it appears to be an Ethernet issue with maintaining the link and DHCP is actually doing the right thing in that case by requesting an IP address on each link up. The problem could be in the hardware at either end or the cable. It would be interesting to know if anyone else seeing this problem also sees the link up/down happening.