When we send packet fragments (created by packet->CreateFragment()), it occurred a problem ("assert failed. file=../src/common/packet-metadata.cc, line=436, cond="m_used != prev && m_used != next") when the receiver try to reassemble the fragment. Note that the receiver reassembles when all the fragments are here.

In the test-case patch, we modify the udp-echo-client and udp-echo-server application in order to send fragment packet for client-side and reassemble them for server-side. In fact we found this bug by implementing the IPv6 fragmentation extension.