TE1
TE2
NT1
NT2
第1题:
阅读以下说明,回答【问题1】~【问题4】,将解答填入空白处。
【说明】某小型单位的网络图如图5所示,Cisco路由器有ISDN模块,单位通过ISDN连接Internet。ISDN是指近年来供最终用户使用的一套数字服务,包括电话网络的数字化,以便ISP能够在现有的电话线路上以一个最终用户接口提供给最终用户多种服务。ISDN用更高速的数字设备代替传统的老式电话业务POTS设备和配线系统。
ISDN的接口可以是PRI或BRI。ISDN的信道有两种类型:B和D。B信道主要是用来运送数据的工具,每个B信道拥有最大可达64kb/s的吞吐量,主要用于电路交换的数据通信,也可用于基于包交换的数据通信。D信道用来传输请求ISDN交换的信令。实际上, D信道提供一个到电信提供商中心局的本地回答,也可用于传送基于包交换的数据(如 X.25)。BRI是最典型的ISDN连接,并且是路由器上的一个本地ISDN接口,基本带宽是 2B+D。
在ISDN的BRI安装中,NT1(NT2)是一个重要的小设备,NT1类似于串行连接中用到的CSU/DSU,它是终接本地回路的设备(其实NT1就是一个将电话2线变4线的设备)。NT1至少有2个接口:一个S/T接口和一个U接口。S/T接口连到路由器的BRI接口上;U接口连接到ISP提供的插座上。许多具有BRI功能的Cisco路由器都有一个集成的NT1接口。这些接口都有一个BRIU标签,如果底板上没有这个特性,则接口会标BRIS/T,从而需要一个外部的NT1。这个本地的ISDN接口就是路由器的TE1接口。TE1终端适配卡专用于连接ISDN。
以下是路由器部分的配置清单:
Router(config) ISDN switch-type basic-5ess
Router(config) interface BRI0
Router(config-if) ip add 192.168.10.1 255.255.255.0
Router(config-if) encapsulation PPP
Router(config-if) dialer idle-time out 1 80
Router(config-if) dialer mapip 192.168.10.2 07314433018 (1)
Router(config-if) dialer-group1
Router(config) dialer-list protocol ip permit
ISDN分哪几层? NT2(网络终端连接设备)提供哪两种交换功能?
第2题:
A. It is used with the OSPF priority values to determine which OSPF router will become the DR or BOR in a point-to-point network
B. It is used with the OSPF priority values to determine which interface will be used to form a neighbor relationship with another OSPF router
C. It is used with the OSPF priority values to determine which router will become the DR or BOR in a multi access network
D. It is used to determine which interfaces will send Hello packets to neighboring OSPF routers
第3题:
[说明]
下面是某路由器的部分配置信息,解释部分语句的含义。
[配置路由器信息]
Current configuration:
!
hostname router1
isdn switch-type basic-net3 (1)
!
interface Ethernet0
ip address 10.0.0.1 255.255.255.0
ip nat inside (2)
!
interface bri 0
ip address negotiated (3)
ip nat outside
encapsulation PPP
PPP authentication pap callin (4)
PPP multlink (5)
dialer-group 1
dialer string 2633
PPP pap sent-username 263 password 263 (6)
ip route 0.0.0.0 0.0.0.0 bri 0
access-list 2 permit any (7)
dialer-list 1 protocol ip permit (8)
ip nat inside source list 2 interface bri 0 overload (9)
……
End
第4题:
A. Nothing. The router is already suitable.
B. A BRI WAN interface in the router.
C. An external NT1 to terminate the local loop.
D. A TA/NT1 device on the router.
第5题:
A.TE1
B.NT-2
C.TA
D.TE2
E.NT-1
第6题:
A. TE1
B. TE2
C. TA
D. NT1
E. NT2
第7题:
At a branch location, TestKing.com has deployed a non modular router that is equipped with two serial interfaces and two Ethernet interfaces.What additional equipment must be used to allow the branch office to connect to the central office by using an ISDN service?()
A. a serial cable with a V.35 to RJ45 adapter
B. a CSU/DSU
C. an external ISDN TA and NT1
D. The non-modular router cannot connect to an ISDN service. The network administrator must purchase a modular router with an ISDN BRI-U card.
第8题:
A.mark
B.color
C.filter
D.discard
第9题:
A.NT2
B.NT1
C.TE
D.TA
E.TE1
第10题:
You have just obtained a modular Cisco router with 2 serial connections and a BRI/U interface. What other physical piece of hardware is required in order to establish an ISDN connection?()