14 replies to this topic

[lesmondo]

Hi, I've been playing with N+ at home plugged into my ADSL router/modem (Billion 7800G) and it works just fine. However, today I took the board into work and had a strange issue when connected to our network. Plugging the N+ into our network - which I believe is some flavour of a cisco gigabit switch - causes the network adapter on the N+ to appear to continually reset. By this I mean the three n/w leds turn on, one blinks a few times then all three turn off for a couple of seconds. This repeats. Originally I was using HttpWebRequest to retrieve some data from a webserver on my PC. This code wass hanging on the GetResponse call. After simplifying the code, I've ended up with a main that only calls Thread.sleep in a loop. The network still appears to reset endlessly. I'm using a static IP and firmware 4.2. Curiously, about 1 in 100 resets, the board functions fine and I can ping it and make socket connections back to the server running on my PC. But for the other 99 times, the board is not pingable. I've brought the board home again tonight, changed the static IP to one on my network and the board works fine. So I'm wondering is it something to do with the networking hardware at work? Thanks

[oofki]

Hi,

I've been playing with N+ at home plugged into my ADSL router/modem (Billion 7800G) and it works just fine. However, today I took the board into work and had a strange issue when connected to our network.

Plugging the N+ into our network - which I believe is some flavour of a cisco gigabit switch - causes the network adapter on the N+ to appear to continually reset. By this I mean the three n/w leds turn on, one blinks a few times then all three turn off for a couple of seconds. This repeats.

Originally I was using HttpWebRequest to retrieve some data from a webserver on my PC. This code wass hanging on the GetResponse call. After simplifying the code, I've ended up with a main that only calls Thread.sleep in a loop. The network still appears to reset endlessly.

I'm using a static IP and firmware 4.2.

Curiously, about 1 in 100 resets, the board functions fine and I can ping it and make socket connections back to the server running on my PC. But for the other 99 times, the board is not pingable.


I've brought the board home again tonight, changed the static IP to one on my network and the board works fine. So I'm wondering is it something to do with the networking hardware at work?


Thanks

Can you post the code you are using?

[lesmondo]

Can you post the code you are using?

Sure. It's basically:

main() { while(true) { Thread.sleep(5000); } }

I thought it was something to do with my code so simplified and simplified until I ended up with that. If you erase the app using mfdeploy so that there's no running program it still does the reset thing.

After reading this, http://forums.netdui...in-the-network/ it looks like I'm seeing the same issue - the link going up and down repeatedly.

[oofki]

Sure. It's basically:

main() { while(true) { Thread.sleep(5000); } }

I thought it was something to do with my code so simplified and simplified until I ended up with that. If you erase the app using mfdeploy so that there's no running program it still does the reset thing.

After reading this, http://forums.netdui...in-the-network/ it looks like I'm seeing the same issue - the link going up and down repeatedly.

I'm no expert, I'm just starting to learn too, but I think it's because you only have one thread and you are blocking it for 5 seconds at a time.

Try this: main() { while(true) { int i = 0; } }

[Chris Walker]

Hi oofki, The Thread.Sleep function simply puts the main thread to sleep...you can have background threads running (including networking) without any issue. Chris

[lesmondo]

Hi oofki,

The Thread.Sleep function simply puts the main thread to sleep...you can have background threads running (including networking) without any issue.

Chris

Thanks Chris, like I said this was my simple as possible test case. Any ideas as to why the network would be resetting like this?

[Chris Walker]

Hi lesmondo,

Thanks Chris, like I said this was my simple as possible test case. Any ideas as to why the network would be resetting like this?

If other devices work on this router, I'm guessing that it's a glitch in the lwIP open source networking stack.

Could you please post a bug report ("work item/issue") on this over at netmf.codeplex.com? The .NET MF 4.2 release is almost ready to ship...so this is the last chance to get critical bug reports in. [Otherwise, it could be a year before the issue is addressed in an official release.]

Also...do you have a copy of Wireshark? It would be really helpful to see a copy of the network traffic...see what is arriving at the Netduino Plus and what is going out...

Chris

[lesmondo]

Hi lesmondo,

If other devices work on this router, I'm guessing that it's a glitch in the lwIP open source networking stack.

Could you please post a bug report ("work item/issue") on this over at netmf.codeplex.com? The .NET MF 4.2 release is almost ready to ship...so this is the last chance to get critical bug reports in. [Otherwise, it could be a year before the issue is addressed in an official release.]

Also...do you have a copy of Wireshark? It would be really helpful to see a copy of the network traffic...see what is arriving at the Netduino Plus and what is going out...

Chris

Hi Chris,

I'll raise a bug report. Unfortunately since our network is switched I don't think I'll be able to capture the N+ packets - my PC doesn't see them.

Les

[Inquisitor]

Hi Chris,

I'll raise a bug report. Unfortunately since our network is switched I don't think I'll be able to capture the N+ packets - my PC doesn't see them.

Les

Although your corporation might frown on it (some will)...
At my day job (an extremely large, security conscious corporation) we run on a gigabit switch network, some of us developers who need to use Wire Shark occasionally will also have a dumb, gigabit hub in our office… plugging in network, Netduino and your PC should allow you to “see” what’s going on between your N+ and the (anti-social ) company switch.

[lesmondo]

Although your corporation might frown on it (some will)...
At my day job (an extremely large, security conscious corporation) we run on a gigabit switch network, some of us developers who need to use Wire Shark occasionally will also have a dumb, gigabit hub in our office… plugging in network, Netduino and your PC should allow you to “see” what’s going on between your N+ and the (anti-social ) company switch.

Shhh..... they might hear you That's what I'm hunting around for now. I'm also thinking that if it is the cisco switch/N+ combo that's the problem, maybe putting a cheap hub between the two might fix it.

[Inquisitor]

Shhh..... they might hear you That's what I'm hunting around for now. I'm also thinking that if it is the cisco switch/N+ combo that's the problem, maybe putting a cheap hub between the two might fix it.

Yeah! I hate that Heisenberg thing.

[lesmondo]

Hi All, I've managed to get one of our networking gurus to do some wiresharking and it appears that it's the Cisco Discovery Protocol packet(s) that are causing the N+ network to reset. The N+ negotiates at 100mb full dup, the switch sends CDP, then N+ network resets. This repeats. I have the capture but since this contains site specific info, it's probably best if I don't attach them here. Does this sound like a MF problem or a N+ hardware problem? Thanks Les

[Chris Walker]

Hi Les, If it's a packet, then it's almost definitely a .NET MF firmware (or lwIP network stack) issue. Unless the packet is accompanied by a voltage spike or something that is Chris

[ColinR]

If it's a packet, then it's almost definitely a .NET MF firmware (or lwIP network stack) issue.

Les, are you able to anonymise the capture data (without jeopardising it) so that a bug report can be submitted on CodePlex including the capture?

[lesmondo]

Les, are you able to anonymise the capture data (without jeopardising it) so that a bug report can be submitted on CodePlex including the capture?

Update: I bought a cheap 10/100 switch from ebay and that's fixed the problem