What is the correct procedure for a VLAN pool to assign terminals to VLANs.

The Next_Hop attribute in BGP records the next hop of a route. Similar to the next hop in an IGP, the Next_Hop attribute in BGP must be the IP address of a peer interface.
Four routers run IS-IS and have established adjacencies. The area IDs and router levels are marked in the following figure. R1 and R2 are connected through a PPP link, and R3 is the DIS. Which of the following statements are true?

Compared with RSTP, which of the following port roles are added to MSTP?