Abstract: P2P streaming media application must realize NAT traversal.The UPUN algorithm is recommended in this paper to increase the success rate of NAT traversal，which is the combination of UPnP and STUN.This paper also presents the algorithm of Port-Adding Sample Estimation（PASE） and Peer Auxiliary-Relay（PAR） to improve traditional methods used in symmetric NAT traversal and the situations which both side peers are behind NATs.Experiments show that the algorithms achieve good performance.

Key words: NAT（Network Address Translation） traversal, UPnP, STUN, sample estimation, auxiliary-relay

摘要： NAT穿越是P2P（Peer-to-Peer）流媒体应用必须要解决的问题，目前已有的单一穿越方法由于各自的局限性造成穿越成功率不高。为此提出UPUN方法，将UPnP和STUN有效结合以提高穿越成功率；同时针对对称NAT的穿越以及通信节点都位于NAT后情况下的穿越提出端口添加样本估计算法PASE和外网节点辅助中继算法PAR，以改进现有算法的不足。实验证明了方法的有效性。

关键词: NAT（网络地址转换）穿越, 通用即插即用, NAT的UDP简单穿越, 样本估计, 辅助中继