The BGP protocol is carried by _______, and its port is _______.

ND protocol packets are encapsulated by _______.

The networking is shown in the figure, RTA and RTB are route reflectors, RTC and RTD are route reflector clients, and RTC and RTD need to learn BGP routes from each other. How should I plan?

Company XZ required to build its network according to a modular enterprise network architecture. XZ Company has 1 R&D base in Shenzhen and Xi'an each; one office building in Beijing and Shanghai; offices with more than 50 people in 23 provincial capital cities; small offices with no more than 8 people in 200 small and medium-sized cities; More than 200 marketing and technical staff are typically traveling at any one time. XZ Company strictly prohibits employees from using the company network to access non-work related websites. According to these circumstances, the network module that XZ company should have is ________.

As shown in the figure, RTA establishes an eBGP neighbor relationship with RTB and RTC respectively, and both RTB and RTC advertise a route N to RTA.
As shown in the figure, if you want RTA to give priority to the route advertised by RTB, and the route advertised by RTC as a backup, you need _____.