A.the number of subscribers that will be serviced currently and in the future because this affects the number of required PPPoA sessions
B.The types of applications that the NSP offers to the end subscriber
C.The capacity of ATM and Frame Relay interworking on the NSP
D.in the case of more than one user， whether all users need to reach the same final destination orservice，or they all have different service destinations
E.Whether the service provider or the final service destination is providing the IP address to the CPE of the subscriber

A.after the Layer 3 header and before the Layer 2 payload
B.after the Layer 3 header and before the Layer 4 payload
C.after the Layer 2 header and before the Layer 1 payload
D.after the Layer 1 header and before the Layer 2 payload
E.after the Layer 2 header and before the Layer 3 payload

A.EBGP sessions between confederation sub ASs do not modify the next-hop attribute.
B.By default， iBGP sessions change the next-hop attribute learned from eBGP peers to self address.
C.By default， the next-hop attribute is not changed when a prefix is reflected by the route reflector
D.EBGP sessions between confederation sub ASs change the next-hop attribute to peer address.
E.By default， iBGP sessions preserve the next-hop attribute learned from eBGP peers.

A.IP protocol 50
B.TCP port 51
C.UDP port 50
D.IP protocol 51
E.UDP port 51
F.TCP port 50

A.the protocol used to determine the authentication method
B.the protocol used to identify the data in the Information field
C.the protocol used to carry the PPP frame
D.the protocol used to decode the FCS field
E.the protocol used to detect the number of padding bytes

A.TCP port
B.authentication
C.IP DF bit
D.retransmit retries
E.sequencing
F.hostname

A.cluster ID
B.Weight
C.MED
D.local preference
E.aggregate

A.Graceful restart allows session information recovery without disruption to the network.
B.A node can perform a graceful restart to help a neighbor recover its state. The label bindings are kepton state information， which helps the failed node recover faster and does notaffect the current for wardtraffic.
C.Graceful restart allows a node to recover state from its neighbor when there is no RP or before thedevice undergoes SSO.
D.Graceful restart does not allow session information recovery.
E.During a graceful restart， the router removes any stale prefixes after a timer for stale entries expires

A.cell loss priority （CLP）
B.discard eligibility （DE）
C.head error control （HEC）
D.generic flow control （GFC）
E.forward explicit congestion notification （FECN）

A.Layer 2 access link QoS design
B.enterprise-to-service-provider mapping models
C.Layer 3 link access QoS design
D.service provider service level agreements
E.Layer 2 link access load balancing