Set the packet size of udp agent to 1400. set udpagent [new Agent/UDP] $udpagent set packetSize_ <newSize> hope this helps, manish Chen Wen-Jen wrote: > > hi... all... > > When I use UDP traffic sources, > it will fragment packets automatically. > for example, > 1400bytes -> 1000bytes + 400bytes > How to avoid this situation? > Can I change default value(1000bytes)? > thanks a lot... :)