fattylewis
Posts: 6
Joined: Wed Dec 05, 2012 10:23 pm

PI2 ethernet packet loss

Fri Jul 03, 2015 2:20 pm

Hi all,

Im struggling to troubleshoot an issue im seeing with my PI2.

Im constantly seeing packet loss. The PI is connected to a known working Netgear GS724T 24 port Gigabit switch. Using a known working port and testing with several known working cables.

Interestingly this only seems to be a "receive" issue, as while im getting packet loss pinging the pi, the pi is pinging out to the internet absolutely fine. I have re-imaged it several times to eliminate config error made by me, ive replaced the PSU twice, Ive used several different switch ports (all of which had working devices in them previously), i have used several cables (again, coming from working devices, also crimped my own to be sure). But this packet loss will not go away.

A few interesting facts:
  • The packet loss doesnt occur the same time from each device (logs below)

    The packet loss doesnt show when connected to my upstream router (images of setup below)
Pings from 2 different devices showing different amount of packet loss:

From my ldap server, this is a VM hosted on an esxi box connected directly to the switch:

Code: Select all

jon@ldap:~$ ping 192.168.0.218 -q -c 100
PING 192.168.0.218 (192.168.0.218) 56(84) bytes of data.

--- 192.168.0.218 ping statistics ---
100 packets transmitted, 85 received, 15% packet loss, time 99000ms
rtt min/avg/max/mdev = 0.265/0.300/0.726/0.050 ms
From my laptop, connected to a wireless access point which is then connected directly to my switch:

Code: Select all

jon@jon-debian-laptop:~$ ping 192.168.0.218 -q -c 100
PING 192.168.0.218 (192.168.0.218) 56(84) bytes of data.

--- 192.168.0.218 ping statistics ---
100 packets transmitted, 70 received, 30% packet loss, time 99239ms
rtt min/avg/max/mdev = 0.752/1.357/16.579/2.089 ms
Setup which shows no packet loss:
http://i.imgur.com/LS3Y3zM.png

Setup which shows packet loss:
http://i.imgur.com/4PNF3hr.png

PI2 Details:

Code: Select all

pi@raspberrypi /etc $ cat debian_version 
7.8

Code: Select all

pi@raspberrypi /etc $ uname -a
Linux raspberrypi 4.0.7-v7+ #801 SMP PREEMPT Tue Jun 30 18:38:23 BST 2015 armv7l GNU/Linux
I'm really not sure where else to go to troubleshoot this?!

myoung008
Posts: 55
Joined: Mon Mar 18, 2013 9:56 pm

Re: PI2 ethernet packet loss

Fri Jul 03, 2015 5:27 pm

I would start with the settings on the Netgear switch. If there isn't something obvious, I'd start by locking the port to 100Mbit, Full Duplex, MDI. I'm guessing here but it seems like it may be continuously trying to renegotiate to gigabit speeds or something like that.

fattylewis
Posts: 6
Joined: Wed Dec 05, 2012 10:23 pm

Re: PI2 ethernet packet loss

Fri Jul 03, 2015 7:38 pm

myoung008 wrote:I would start with the settings on the Netgear switch. If there isn't something obvious, I'd start by locking the port to 100Mbit, Full Duplex, MDI. I'm guessing here but it seems like it may be continuously trying to renegotiate to gigabit speeds or something like that.
Nice thinking but no joy. Tried disabling auto neg on both and both to 100FD. I even went as far as trying it on 10HD.

myoung008
Posts: 55
Joined: Mon Mar 18, 2013 9:56 pm

Re: PI2 ethernet packet loss

Fri Jul 03, 2015 7:59 pm

My network topology is similar to yours, only a switch connected to the main router and everything else (including more switches for other parts of the house) coming off that. I don't have any issues with pings to/from any host to/from any other.

I'm using a mix of "dumb" switches and a TP-Link TL-SG1024DE "Smart" switch. Just plugged in the smart switch and have a ping going through it as well as two dumb switches right now, no packet loss.

Maybe time for a new switch?

By the way, that's NOT a recommendation for this particular TP-Link switch, Their next level switch is only slightly more expensive and much better.

fattylewis
Posts: 6
Joined: Wed Dec 05, 2012 10:23 pm

Re: PI2 ethernet packet loss

Fri Jul 03, 2015 8:10 pm

myoung008 wrote:My network topology is similar to yours, only a switch connected to the main router and everything else (including more switches for other parts of the house) coming off that. I don't have any issues with pings to/from any host to/from any other.

I'm using a mix of "dumb" switches and a TP-Link TL-SG1024DE "Smart" switch. Just plugged in the smart switch and have a ping going through it as well as two dumb switches right now, no packet loss.

Maybe time for a new switch?

By the way, that's NOT a recommendation for this particular TP-Link switch, Their next level switch is only slightly more expensive and much better.
Hmm i hope its not the switch as its only about 2 months old. I have about 18 other devices coming off this switch (structured cabing going to most rooms in the house) as well as a couple of bonded interfaces for servers and none exhibit this behaviour.

I've got a couple of dumb switches knock around and also an old cisco 24port 10/100 switch that ill test with tomorrow.

fattylewis
Posts: 6
Joined: Wed Dec 05, 2012 10:23 pm

Re: PI2 ethernet packet loss

Sat Jul 04, 2015 11:14 am

Just a super quick update. I am beginning to think this is nothing to do with the pi itself and im actually even more confused.

I've just spun up a new virtual machine on my esxi host, this new VM is showing the packet loss...pinging another VM on the exact same host at the exact same time does not show this behaviour?! Im so confused now.

myoung008
Posts: 55
Joined: Mon Mar 18, 2013 9:56 pm

Re: PI2 ethernet packet loss

Sat Jul 04, 2015 3:41 pm

I'd try pinging between several of your local hosts not on the ESXi box to see if you can tie it to that one machine. If so, then it's probably in the network config for the hypervisor/VMs on that box. I'm afraid I won't be of much help there, I've not used any VMWare product in about 10 years.

fattylewis
Posts: 6
Joined: Wed Dec 05, 2012 10:23 pm

Re: PI2 ethernet packet loss

Sat Jul 04, 2015 5:45 pm

myoung008 wrote:I'd try pinging between several of your local hosts not on the ESXi box to see if you can tie it to that one machine. If so, then it's probably in the network config for the hypervisor/VMs on that box. I'm afraid I won't be of much help there, I've not used any VMWare product in about 10 years.
This is getting weird. Built another VM using centos, works fine. Rebuilt pi using fedora arm remix....works fine. 2000 pings, 0% packet loss. Im going to try an older version of Raspbian on my pi later to see if it something thats been updated, but i would assume someone else would see this aswell?

myoung008
Posts: 55
Joined: Mon Mar 18, 2013 9:56 pm

Re: PI2 ethernet packet loss

Sat Jul 04, 2015 5:52 pm

I don't recall having any packet loss to speak of on any version of the Raspbian, or any other Pi distro for that matter. I've not seen many users having that issue, either.

fattylewis
Posts: 6
Joined: Wed Dec 05, 2012 10:23 pm

Re: PI2 ethernet packet loss

Sat Jul 04, 2015 5:53 pm

myoung008 wrote:I don't recall having any packet loss to speak of on any version of the Raspbian, or any other Pi distro for that matter. I've not seen many users having that issue, either.
Same here, i need to do some more investigating i think.

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