perfSONAR User Q&A and Other Discussion

[Mark Foster <>]

ping -M do -s 8972

the "-M do" is important in most contexts, since it says "prohibit 
fragmentation". If it's not 9000-byte clean path, you won't get a ping response.

On 9/24/2015 11:52 AM, Jason Zurawski wrote:
> Greetings;
>
> Besides the end hosts being configured for Jumbo frames, the entire broadcast 
> domain needs to be working with jumbo frames as well (e.g. the switch, and 
> devices populating it).  If something is mis-configured, the application will 
> not function.  You can test to be sure you have a clean 9000 byte path with 
> 'ping -s 8972'.
>
> Thanks;
>
> -jason
>
> Xu Chen wrote:
> > Their MTU size is also 9000.
> >
> > > On Sep 24, 2015, at 2:35 PM, Brian Jones 
> > > <
> > >  
> > > <mailto:>>
> > >  wrote:
> > >
> > > You may want to check the testing end point sides mtu size.
> > >
> > > fwiw
> > >
> > > --
> > > Brian
> > >
> > > On Thu, Sep 24, 2015 at 2:26 PM, Xu Chen 
> > > <
> > >  
> > > <mailto:>>
> > >  wrote:
> > >
> > >     Hello all,
> > >
> > >     I use 10G NIC on my perfSONAR node. When I start a tcp throughput test 
> > > from my node to another node, the throughput is 1.2 Gbps (before I use 10G 
> > > NIC, it’s 911Mbps). After I reserve the the source and destination, the 
> > > result becomes 0.4 Gbps. I use default TCP window size and MTU is 1500.  What 
> > > do I miss on the configuration (perfSONAR toolkit or NIC)?
> > >
> > >     Another problem is when I change MTU from 1500 to 9000 (ifconfig eth0 mtu 
> > > 9000 up), I met the following problem when starting a test.
> > >     bwctl: Using tool: iperf
> > >     bwctl: 26 seconds until test results available
> > >
> > >     RECEIVER START
> > >     ------------------------------------------------------------
> > >     Server listening on TCP port 5191
> > >     Binding to local address 140.221.68.2
> > >     TCP window size: 87380 Byte (default)
> > >     ------------------------------------------------------------
> > >     [ 15] local 140.221.68.2 port 5191 connected with 129.63.79.200 port 47521
> > >     Waiting for server threads to complete. Interrupt again to force quit.
> > >
> > >     bwctl: local tool did not complete in allocated time frame and was killed
> > >     What should I do so that I can use jumbo frame?
> > >
> > >     Thanks,
> > >
> > >     Chen Xu