IP Over SDH与IP Over ATM比较，以下说法正确的是（）

A . 网络体系结构复杂 B . 传输效率低 C . 不适应于多业务 D . 网络体系结构复杂和传输效率低

A . SDH帧格式 B . GE以太网帧格式 C . PDH帧格式 D . SDH帧格式或GE以太网帧格式

A . A voice packet is sent via multiple fixed-length cells; a portion of the last cell is padding, requiring more bandwidth. B . ADSL typically uses PPPoE encapsulation, which adds additional overhead to each voice packet. C . A voice packet is sent via multiple fixed-length cells; each cell has about 10% Layer-2 header overhead.  D . IPSec requires additional overhead for the header and hash.  E . ADSL carrier band requires additional bits to be carried over the wire to the DSL Access Concentrator.

A . 79xx IP phones do not automatically mark voice packets with non-zero DSCP values. B . 79xx IP phones do not mark protocol packets such as DHCP, DNS, or TFTP with non-zero DSCP values. C . 79xx IP phones do not mark voice packets with optimal DSCP values. D . 79xx IP phones use a custom protocol to communicate CDP information to the switch.

A . 正确 B . 错误

A . switchport priority extend trust   B . mls qos trust C . switchport priority extend cos 7   D . auto qos voip cisco-phone

A .  Packets can arrive out of order. B .  Packets must take the same path to the destination. C .  Once packets are received at the destination router， the router performs sampling to ensure the quality of the voice traffic. D .  Packets can experience varying delays across the network. E .  Packets containing voice samples are sequentially numbered by default， allowing for reordering upon arrival at the terminal router along the path.

A . 正确 B . 错误

A . termination devices need routable addresses inside the VPN B . termination devices need not routable addresses inside the VPN C . IGP routing protocols will update their routing tables over anIPsec VPN D . addressing designs need to allow for summarizatio

A . WDM B . OA C . OTU D . POS

A . RIPv1 B . RIPv2 C . EIGRP D . OSPF

A .  Some network attributes are runtime attributes that can be changed at any time. Others are loadtime attributes that must be set before the netinet kernel extension is loaded and be placed in the /etc/rc.net or /etc/rc.bsdnet file. This parameter cannot be done on the fly， since a reboot is required. B .  Add to the /etc/rc.net file or if a Berkelye-style network configuration， /etc/rc.bsdnet， and issue the command： no -a ipforwarding=1 to start ipforwarding immediately. C .  Add to the /etc/rc.net file or if a Berkeley-style network configuration， /etc/rc.bsdnet， and issue the command： no -o ipforwarding=0 to start ipforwarding immediately. D .  Add to the /etc/rc.net file or if a Berkeley-style network configuration， /etc/rc.bsdnet， and issue the command： no -o ipforwarding=1 to start ipforwarding immediately.

A . 正确 B . 错误

A . MPLS B . ATM C . MSTP D . MTPS

A . 正确 B . 错误

A . LCAS B . PPP C . HDLC D . GFP

Network managers have long awaited practical voice-over-IP(VOIP)solutions. VOIP promises(71)network management and decreases costs by(72)a company's telephony and data infrastructures into one network. And a VOIP solution implemented at a company' s head -quarters with far -reaching branch offices can(73)tremendous amounts of(74)in long distance phone bills, provided that solution delivers POTS -like voice(75)over the Internet. A．complicated B．useful C．ease D．orderly

A．A.PPP和HDLC B．B.PPP和SDH C．C.HDLC和SDH D．D.IP和PPP

A.RIPv1 B.RIPv2 C.EIGRP D.OSPF