单项选择题
BGP is an inter-autonomous system routing protocol;
it is designed to be used between multiple autonomous______.BGP assumes that
routing within an autonomous system is done by an intra-autonomous system
routing protocol. BGP does not make any assumptions about intra-autonomous
system______protocols employed by the various autonomous systems. Specifically,
BGP does not require all autonomous systems to run the same intra-autonomous
system routing protocol.
BGP is a real inter-autonomous system
routing protocol. It imposes no constraints on the underlying Internet topology.
The information exchanged via BGP is sufficient to construct a graph of
autonomous systems connectivity from which routing loops may be pruned and some
routing______decisions at the autonomous system level may be enforced.
The key feature of the protocol is the notion of Path Attributes. This
feature provides BGP with flexibility and extensibility. Path______are
partitioned into well-known and optional. The provision for optional attributes
allows experimentation that may involve a group of BGP______without affecting
the rest of the Internet. New optional attributes can be added to the protocol
in much the same fashion as new options are added to the Telnet protocol, for
instance.MSTP(基于SDH的多业务传送平台)是一种重要的广域网技术，在我国可采用的工作机制可概述为______。
A.路由设备的以太接口划分出若干的逻辑子接口，PTN设备将不同分支路由设备的捆绑T1/T3/E1/E3电路上的数据帧映射至不同的子接口
B.路由设备和传输设备的以太接口都工作在VLAN
Trunk模式，传输设备将不同分支路由设备的捆绑E1/E3/E4电路上的数据帧映射至不同的VLAN中
C.路由设备的以太接口划分出若干的逻辑子接口，传输设备将不同分支路由设备的捆绑T1/T4/E1/E4电路上的数据帧映射至不同的子接口
D.路由设备和PTN设备的以太接口都工作在VLAN
Trunk模式，DXC设备将不同分支路由设备的捆绑T1/T3/E1/E3电路上的数据帧映射至不同的VLAN中
