In the Ethernet access application, the correct statement about the deployment of the access point AN and the aggregation equipment AGG at the edge of the operator's access network is ____ .

The four routers R1 , R2 , R3, and R4 are connected in sequence, and Loopback0 interfaces are created on R1 and R4 , and the interface addresses are 1.1.1.1 and 4.4.4.4 respectively.The four devices are configured with static routing protocols to ensure Loopback0 of R1 and R4 .The address is reachable, and a GRE Tunnel is established between R1 and R4 .Check the tunnel interface information on R1 as follows:
[R1]displa interface Tunnel O
Tunnelo current state: UP
Tunnelo current statle: UP
Line protocol current state: UP
Description: Tunnel 0 Interface
The Maximum transmit Unit is 1476
Internet Addess is 10.1.1 .1/30 Primar.
Encapsulation isTUNNEL aggregation ID not set
Tunnel source l.1.1.1 destination 4.4.4.4
Tunnel keeepalive disable
Tunnel protocol/transport GRE/IP.
GRE key disable
Checksumming of GRE packets disabled
Last 300 seconds input:.2 btes/secl 0 packet/sec.
Last 300 seconds output:..2 bytes/sec , 0 packets/sec.
15packets input 840bytes.
0 input error
27packets output , 1248btes
0 0utput error
At this time, if the interrupt R2 and R3 link between, the following statement is correct ____

When a PPP frame is encapsulated by adding an L2TP header, it will be marked with the correct Tunnel ID and Session ID to identify its tunnel and session attributes.The Tunnel ID ( tunnel identifier ) in the L2TP header is assigned by ____ , and the Session ID ( session identifier ) is assigned by ____ .

The process of LDP session establishment is ______ .

The following functions of the convergence layer are ____ .( Choose one or more )