A.the FXS interface allows an analog connection to be directed at the public switched telephone network （PSTN’s） central office
B.the FXS interface connect directly to a standard telephone， fax machine， or sililar device and supplies ring， voltage， and dial tone
C.the FXS interface connect directly to an IP phone and supplies ring， voltage， and dial tone
D.the FXS interface connect directly to ISDN voice channels

A.the Cisco WCS is designed to support 1500 Cisco WLAN controllers and up to 50 APs
B.the Cisco WCS runs on a dedicated network device such as the Cisco 2700 network appliance
C.the Cisco WCS runs on various windows and Linux platforms
D.the Cisco WCS screen displays four main menu sheet tab consisting of Monitor， Configure， Security， and Alam
E.the Cisco WCS uses the SNMP protocol to communicate with the controllers

A.Asynchronous Transfer Mode （ATM）
B.data-link switching （DLSw）
C.Route Processor Redundancy （RPR）
D.Frame Relay （FR） 
E.Metro Ethernet
F.Multiprotocol Label Switching （MPLS）

A.a class can be identified as a single application， multiple applications with similar service needs，or be based on the source or destination IP address
B.a drawback of the DiffServ field in the MAC header to mark frames into behavior aggregates （BAs）
C.DiffServ uses the DiffServ field in the MAC header to mark frames into behavior
D.the DiffServ field occupies the same eight bits of the MAC header that were previously used for the ToS field
E.the first six high-order bits of the DiffServ field are used to identify the Resource Reservation Protocol （RSVP） value
F.the primary goal of DiffServ is scalability

A.FECN
B.LLQ
C.WRED
D.LFI
E.CRTP
F.CBWFQ