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

A.MD5 has been used by BGP to encrypt BGP update packets.
B.BGP uses a message-digest algorithm to authenticate BGP peers
C.A plain-text password authentication is an option of BGP authentication
D.EBGP peers authentication is faster than IBGP peers authentication
E.BGP uses public key and private key to authenticate BGP peers.

A.BE
B.AF41
C.AF21
D.EF
E.AF31

A.The RT is a BGP extended community.
B.The RT is an 8-byte field that is prefixed to an IPv4 address to make it a unique VPNv4 address.
C.When a VPN route that is learned from a CE router is injected into BGP， one or more RTs are associated with it
D.The distribution of VPN routing information is controlled through the use of VPN RTs
E.When a VPN route that is learned from a CE router is injected into BGP， there is always one RT that is associated with it.

A.rooted multipoint EVC （E-Tree）
B.point-to-point EVC （E-Line）
C.point-to-multipoint EVC （E-Tree）
D.hub spoke EVC （E-Tree）
E.multipoint-to-multipoint EVC （E-LAN）