单项选择题
VLAN Tagging, also known as Frame Tagging, is a method developed by Cisco to help identify packets travelling through trunk links. When an Ethernet frame traverses a trunk link, a special VLAN tag is added to the frame and sent across the trunk link .How does ERS use the VLAN tag?（）
A. provide service internetworking B. support transparency for Layer 2 frames C. indicate destination as a connection identifier D. map to the DLCI in service internetworking
单项选择题 When is the site-to-site remote access model appropriate? （）
单项选择题 Which of these statements best describes VPLS?（）
多项选择题 Which two benefits does VoFR provide?（）
