With the development of the network and the improvement of the tmn requirement , exchange system outputs more and more data . the file transfer system based on x . 25 link ca n ' t meet this requirement 隨著網(wǎng)絡(luò)的發(fā)展,網(wǎng)絡(luò)管理要求的提高使得交換系統(tǒng)向外輸出的數(shù)據(jù)量大幅度增加,所以使得建立在x . 25鏈路基礎(chǔ)上的文件傳送系統(tǒng)無法滿足這些要求。