Atsushi Kara Takahiro Suzuki Kenta Takahashi Masayuki Yoshikaw A DoS-Vulnerability Analysis of L2TP-VPN. 397-402 2004 conf/IEEEcit/2004 CIT http://csdl.computer.org/comp/proceedings/cit/2004/2216/00/22160397abs.htm db/conf/IEEEcit/IEEEcit2004.html#KaraSTY04