The Frame Relay FR (Frame Relay) protocol works at the quantity link layer of the OSI reference model and is a WAN technology mainly used in operator networks
1. Basic Principles of Frame Relay
Frame Relay network provides the ability for data communication between user equipment
User equipment is called data terminal equipment DTE . The equipment that provides network access for user equipment is called the data circuit termination equipment DCE
Second, the virtual circuit
Frame relay networks use virtual circuits to connect frame relay devices at both ends of the network
Each virtual circuit is identified by a data link connection identifier DLCI
1. LMI negotiation process
The local management interface LMI protocol maintains the frame relay link status and PVC status through status query messages and status reply messages
2. Inverse ARP negotiation process
The main function of Inverse ARP is to obtain the IP address of the peer device of the virtual circuit
3. Frame Relay and Split Horizon
RTB sends RTA a routing message, but due to the split horizon mechanism, RTA cannot forward this routing message to RTC through the Serial1 / 0/0 interface that receives the routing message.
4. Frame Relay sub-interface
Configure multiple sub-interfaces on a physical interface, each sub-interface is connected to the peer router using a virtual circuit, so that the problem caused by split horizon can be solved
3. Frame Relay Configuration-Dynamic Mapping
RTB needs to be configured with the same dynamic mapping
2. Frame Relay Configuration-Static Mapping
