perfSONAR User Q&A and Other Discussion

[Andreas Demetriou <>]

Hi Szymon,

 

Thanks for your reply.

 

So I’m just trying to intrepret these results and not sure how reliable they, whether it’s the network link or hardware dropping UDP packets.

Below I have run the “netstat -suna” which shows the UDP errors on a perfsonar node that is currently experiencing packet loss.

 

 

 

I just trying to understand the relevancy and significance of the results.

Could it be that the UDP buffer size is not big enough?

Or the hardware itself is skewing the results?

 

Regards,

 

Andreas Demetriou| Placement Network Engineer

 

Gigaclear plc, Windrush Court, Abingdon, Oxfordshire, OX14 1SY

M: 07976649731 T: 01865591142 W: www.gigaclear.com

Gigaclear plc is registered in England and Wales with company number 07476617

 

From: Szymon Trocha [mailto:]
Sent: 11 May 2017 15:46
To: Andreas Demetriou <>
Cc:
Subject: Re: [perfsonar-user] Ping vs owping

 

W dniu 10.05.2017 o 18:00, Andreas Demetriou pisze:

Hi,

 

Just a question about the difference between ping and owping.

 

So if I have owamp running between two nodes (node A & B), Node A has opened an owamp seesion to Node B. Now node A is experiencing packet loss to Node B but return has no packet loss.

But when running a normal ping from node A to node B there is no packet.

 

What I’m trying to ask is; can you tell me why I’m seeing packet loss using owamp and no packet loss with just a normal ping?

 

 

Hi Andreas,

ping and owamp are two different tools. owamp uses a train of small and evenly spaced groupings of UDP (not ICMP) packets while default ping is a packet every second.  This may reveal a different network behaviour you observe.

regards,

-- 

Szymon Trocha

Poznań Supercomputing & Networking Center

Tel. +48 618582022 ::: http://noc.pcss.pl