After the VPN route cross succeeds, the ingress PE device performs tunnel iteration based on the destination IPv4 address to find the appropriate tunnel. CE1 injects the route to the BGP routing table after receiving it. CE1 must advertise routes to CE2 to ensure device communication. The process is similar to the preceding process. After receiving the packet on the interface bound to a VPN instance, the ingress PE device processes the packet through the following process:.
The packet then travels across the backbone network with double MPLS labels. Each P device on the backbone network swaps the outer label of the packet. P2 receives the packet carrying double labels and sends it to the MPLS protocol module. The egress PE device then only identifies the inner label. Discovering it at the bottom of the label stack, the egress PE device pops the inner label. The packet is successfully transmitted from CE1 to CE2.
CE2 transmits the packet to the destination according to the IP forwarding process. One label per instance Each VPN instance is assigned one label. Public Network Tunnel Iteration Tunnels need to be established on the public network to transmit the traffic of private networks across a public network.
When multiple routes to the same destination are available, a PE device selects one route based on the following rules if load balancing is not configured: If a route received from a local CE device and a cross route are destined to the same destination, the route received from the local CE device is preferred.
When a packet intended for It forwards packets with the speed of Layer 2 protocols while preserving the scalability and dynamic capabilities of Layer 3. The routers using MPLS forwarding tables do not find the need to open Layer 3 headers of packets, thereby saving resources and time. Basically, LSP is a predefined path that the packet takes during transmission. Wikipedia says that a virtual private network extends a private network across a public network and enables users to send and receive data across shared or public networks as if their computing devices were directly connected to the private network.
It does so by constructing a virtual tunnel between the endpoints. Transportation of data between these ends is achieved by encapsulating an entire data packet into a datagram, thereby allowing a safe exchange of data across public or shared networks. In such a network, the service provider runs ATM or Frame Relay to provide connectivity, which typically forms the backbone network. A virtual network built on top of existing network infrastructure Underlay is called an Overlay.
This technique of overlaying a virtual network on an underlay increases the scalability of the network and supports multi-tenancy, modularity and virtualization.
They are equipped to send and receive packets with MPLS labels and take routing decisions accordingly. Customer networks run Layer 3 routing protocols internally. It is vital that P routers in the provider network do not receive a packet with just the VPN label. They are not configured to handle such a packet, thereby resulting in its drop. Devices where VPN instances are configured. Figure One label per instance. Figure One label per next hop. NOTE: One-label-per-route label distribution and one-label-per-next-hop label distribution can be flexibly switched to each other.
Benefits Using an appropriate label distribute mode saves label resources. One label per instance.
0コメント