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MikroTik App
 
brianlewis
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Packet Loss to Ethernet Interface

Sat Feb 05, 2005 1:03 am

I am trying to diagnose an issue we are having with a new router we built to serve as our main router for our 25mbps traffic network.
We have a Celeron 2.8ghz, 512mb, 128mb flash drive, Intel 865 Chipset
Marvell Gigabit interface (LAN) and 3Com 3c509b Interface (WAN) using software Mikrotik v2.8.23

Cox provides us a 100mbps full duplex connection. We have that feed via a regular CAT5E cable from the Cox Switch to our Mikrotik Router 3Com 3c509b interface.

We are currently pulling 7mbps from the internet and pushing out 2.3mbps

Router is running at 10-15% utilization

No Firewall Rules, No Queues except for the BRIDGE we have setup handling EOIP to our old location which we are moving servers from and need setup to allow us to easily change ip addresses over on our own time schedule.

The problem is that from the internet, if we do a continuous ping to our Mikrotik 3Com 3c509b interface ip we get some packet loss, about 5-10%. If we run the same ping to the wan ip of the cox switch, we get no packet loss, so basically the Mikrotik router is missing a beat when it comes to responding to these packet requests.

This in turn has us worried because when we are using Remote Desktop or Telnet/SSH we notice a pause or two at times when talking to the servers behind the Mikrotik from the Internet.

Anyone have any ideas on what might be causing the Mikrotik software to miss a beat at times?
 
UniKyrn
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Sat Feb 05, 2005 2:37 am

Make sure the duplex setting for the port is correct. We discovered the hard way with our upstream link that even though we force the config to 100/full, every time we reboot the router we have to login, switch it to half and then switch it back to full duplex to actually get it set to that mode. What you would think were the saved settings that would be configured each reboot don't actually work. A call from our upstream confirmed that we were seeing a very high error rate on our line until we forced the setting each time, then the error rate dropped to almost nothing. The fact that a MT doesn't report error stats on the ethernet port was another blackmark, we'd have found the problem much sooner otherwise.

This was using one of the 4 port ethernet cards they support, I don't remember if it's the 44 or 24 model.
 
brianlewis
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Location: Irvine, CA

Sat Feb 05, 2005 9:15 am

You nailed it! The 3com and Intel nics I tested both did not auto negotiate properly. In Mikrotik it did not have Full Duplex Green, yet the Allied Cox Switch had a green light for full duplex! I unchecked auto negotiate and Mikrotik Full Duplex turned green and now packet loss is history!
 
the_time
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Sat Feb 05, 2005 12:08 pm

We haf the same problem just disable auto-negation and everything work perfect.
 
UniKyrn
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Sat Feb 05, 2005 6:05 pm

Disabling auto negotiate and forcing the mode corrects the issue, the bug is that the forced mode won't initialize that way if you reboot the router. That's why I have to remember to go in and manually force the mode ever time we reboot it, at least using one of the four port ethernet cards. Maybe the drivers for some of the other cards work correctly, but the 4 port cards are broken.

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