When an MPLS Layer 2 VPN runs in the hub-and-spoke model， where is QoS implemented？（）

多项选择题Allsecuredomainrouters（SDRs）havesharedattributeandresources.WhichthreeresourcesaresharedallSDRs？（）

A.privilege-level configuration
B.fabric cards
C.SNMP traps
D.admin- level configuration
E.exec- level configuration

单项选择题WhichstatementaboutVPLSistrue？（）

A.All CE devices emulate a bridge
B.All provider devices emulate a bridge
C.Hierarchical VPLS reduces signaling overhead
D.Each PE device emulates a bridge
E.Each CE device emulates a bridge

单项选择题Whatmethodofstreaminglivevideoistheleasttaxingonbandwidthinalargeenterpriseenvironment？（）

A.TCP
B.UDP
C.HTTP
D.Multicast

单项选择题WhichstatementisFALSEconcerningConcatenation？（）

A.It allows ITCM to send multiple upstream packets in one single large burst.
B.It reduces upstream data throughput.
C.It can be enabled/disabled from CMTS on per upstream port basis if desired
D.Concatenation activity on an interface can be checked by the show controller counters command

单项选择题Inopticaltransmissionsystems，chirpedlasersareusedforthepurposeof：（）.

A.Turning the laser to a specific ITU channel
B.Keeping the signal wavelength "locked" to a specific technology
C.Suppressing FWM and SBS non-linear effects
D.None ofthe above