Intermittent Pings from clients machines
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Author:  Ovo [ Tue Feb 04, 2014 12:16 pm ]
Post subject:  Intermittent Pings from clients machines

We are using the Pro version 256 licence and about 100 clients across various locations and networks.

I'm getting intermittent ping's using NeoRouter to ping to remote clients.

I get 4-5 successful ping's and then times out then for 10-14 tries then returns.

It seems to settle down if I restart the NeoRouter service or change from UDP to Relay and back for a while.

Things I've changed in Feature.ini:-
ServerAuthBacklog=10 changed to

I thought it might be a congestion thing.

Any suggestions welcome.


Author:  kevinz [ Wed Feb 05, 2014 7:52 am ]
Post subject:  Re: Intermittent Pings from clients machines

Hi Ovo,

It looks like UDP packets got dropped somewhere.

If some traffic control get enabled, some packets, including UDP would be delayed or shaped, Since ping (icmp) is a simple protocol, it may lost packets when UDP packets lost.

2.socket buffer
OS may drop packets from socket buffer when busy. You can adjust the socket buffer size of NR client. Please take a look at the performance tuning guide of NR, ... 111_en.pdf

NR clients may create UDP P2P connection between peers. Unlike TCP, UDP is an unreliable protocol, so it's possible to lost packets. However, the applications over NR network should be able to handle it.

KevinZ - NeoRouter team

Author:  Ovo [ Wed Feb 05, 2014 1:04 pm ]
Post subject:  Re: Intermittent Pings from clients machines

Hi Kevinz

Thanks for the reply.

I'm familiar with networking and traffic types.

I guess before I start drilling down with capturing packets, I wanted to make sure this wasn't a simple configuration issue.

Can you recommend the best debugging method within NeoRouter to capture the information I need to best narrow down this issue. E.g. switches for the Log.ini file.



Author:  kevinz [ Wed Feb 05, 2014 7:14 pm ]
Post subject:  Re: Intermittent Pings from clients machines

Hi Ovo,

Assume your UDP issue can be reproduced.

Please follow the steps below to troubleshoot:

1.Change the connection settings of NR client to use "relay mode", then try ping and see if the ping is stable. If ping is stable, it means the NR server can handle the traffic properly.

2.Change to UDP P2P option to reproduce the issue. Use tcpviewer to check NR client service does create UDP connection. If you can use wireshark to monitor the NR adapter, it would be helpful. When you run ping, you should be able to see the icmp packets and see if they are dropped or delayed. You can also run a tcp app (for example: vnc) over NR and monitor the packets. If you see the TCP packets (vnc over NR) mis-ordered or re-sent, it means the UDP packets (NR) would be lost or delayed (mis-ordered).

You can modify Feature.ini file on client side to increase the buffer, then test see if any changes.

a.When create UDP connection between peers, no traffic goes through NR server.
b.When create UDP connection, it may take 1 minutes to establish the connection. Generally you may see one or two ping response, then a long ping response (if server is slow, may see timeout, as it may take more than 1s), then back to shorter and stable ping responses. It means UDP tunnel is ready and it switch to the P2P tunnel. So it will be faster than before. If you see it back to the same response after the long response, P2P tunnel may not be ready and it keep the relay mode. The long response is caused by P2P tunnel creator, but only one or two.
c.In NR Configuration Explorer or web console, please use Packet Filter feature to filter out all broadcast/ivp6 packets if you don't need, as they may slow down your server.

KevinZ - NeoRouter team

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