Implementation of VPNs over a link state protocol controlled Ethernet network

摘要

Nodes on a link state protocol controlled Ethernet network implement a link state routing protocol such as IS-IS. Nodes assign an IP address or I-SID value per VRF and then advertise the IP addresses or I-SID values in IS-IS LSAs. When a packet is to be forwarded on the VPN, the ingress node identifies the VRF for the packet and performs an IP lookup in customer address space in the VRF to determine the next hop and the IP address or I-SID value of the VRF on the egress node. The ingress node prepends an I-SID or IP header to identify the VRFs and then creates a MAC header to allow the packet to be forwarded to the egress node on the link state protocol controlled Ethernet network. When the packet is received at the egress node, the MAC header is stripped from the packet and the appended I-SID or IP header is used to identify the egress VRF. A customer address space IP lookup is then performed in the identified VRF on the egress node using the information in the client IP header to determine how to forward the packet. Customer reachability information within a VPN may be exchanged between VRFs using iBGP, or directly by using link state protocol LSAs tagged with the relevant I-SID.

主权项

1. A method of exchanging routing information across a link state protocol controlled Ethernet network between Virtual Routing and Forwarding tables (VRFs) associated with an IP VPN, the method comprising the steps of:
implementing a link state routing protocol in a control plane on an Ethernet network, the link state routing protocol being implemented in the control plane to enable the nodes on the Ethernet network to exchange link state advertisements containing information about node adjacencies and link states of the Ethernet network, and to enable the nodes on the Ethernet network to build link state databases containing synchronized views of the topology of the link state protocol controlled Ethernet network and to control the installation of forwarding state at the Ethernet nodes; implementing a first VRF relating to an IP VPN on a first of the nodes; implementing a second VRF relating to the IP VPN on a second of the nodes; and using the link state advertisements of the link state routing protocol to implement an exchange of VPN network layer reachability information between the first VRF and second VRF.