单项选择题
Once the TCP connection is established, which message type initiates the BGP peering process?（）
A. Open B. Active C. Update D. Keepalive E. Notification
多项选择题 What are two purposes of the AS_PATH attribute?（）
单项选择题 What is the first step in BGP route selection?（）
单项选择题 Two Level 2 routers are exchanging Hello packets with different Area IDs. What occurs between these routers?（）
