IP交换是一种利用交换硬件快速传送IP分组的技术。一台IP交换机由(35)3部分组成。IP交换机初始化后为每一个物理连接建立一个默认的(36)，相邻的IP交换机通过这些默认通道交换路由信息和数据分组。为了进行第3层路由选择，IP交换控制器必须根据(37)等信息对网络数据流进行分类并加上数据流描述符。

(159)

(158)

(157)

For each blank, choose the best answer from the four choices and write down on the answer sheet.

(71)is a one-way function that takes an arbitrarily long piece of plaintext and from it computes a fixed-length bit string.

(72)is a protocol that most USENET machines now use it to allow news articles to propagate from one machine to another over a reliable connection.

(73)is an approach preferred by cable TV providers. In this solution the fiber terminates at an optoelectrical converter and the final segment is a shared coaxial cable.

(74)is a device used to connect two separate network that use different communication protocol.

(75)is a digital-to-digital polar encoding method in which the signal level is always either positive or negative.

(156)

(153)

(154)

(152)

帧中继网的虚电路建立在()

(151)