Ping stress (>=990 bytes)

Gene Smith gds at
Mon Aug 18 19:42:55 UTC 2008

Keith Robertson wrote:
> Gene Smith wrote:
>> Another question on dropped packets. I am able to ping (even flood ping) 
>> up to a length of 980 bytes with no loss. When I go over this my tcp/ip 
>> stack seem to go bad. Regular pings (56 bytes) sometimes don't respond, 
>> or responds with a huge amount of data (1022 bytes). Is there a maximum 
>> ping length in rtems?  I see no bad stats in netdemo. My (newly made) 
>> driver has buffers for 1536 bytes.
>> Wondering if others can ping the rtems stack with >=990 bytes?
> On rtems 4.8.1 (and earlier as well), I can successfully ping rtems 
> devices with packets of 65507 bytes (the icmp max).  It takes longer, 
> but it works fine.
> This is on the powerpc/virtex bsp.
> Keith

Thanks for verifying this. Had a problem in the driver where the send 
length wasn't being initialized right. Also, needed to allocate more 
receive/xmit buffers in the driver to receive/send 65507 byte frames. So 
now I can ping with -s 65507. Looks pretty good!


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