BGP Maintenance Analysis of lingke Router

All PE routers in the mpls vpn Network maintain only the ipv4 routing information required for direct connection to the VPN, this feature is implemented by inputting only specific VPN-IPv4 routes that are related to the RT configuration in the VRF, however, this implementation produces a problem, all BGP routes are maintained in the MP-BGP routing table of the PE router, even if some routes are not used in any VRF, in terms of PE router memory, it is also a significant waste of resources to advertise such information to PE routers that do not use it across backbone networks. Www.2cto.com
1. MP-BGP through some mechanisms to avoid appeal problems, PE router on the automatic routing filtering, because the PE router may receive some routing information they do not need, therefore, we hope to filter the MP-IBGP route update received by the PE router at the entrance, and the automatic route filtering feature meets the filtering requirements. 2. When the rt value of the MP-IBGP route received by the PE router does not match the VRF configured in any PE, the PE router will discard it, to reduce the amount of information that the PE needs to store in memory, all PE routers enable this feature by default, without any additional configuration to enable it.
3. the PE router acts as a route reflector for other PE routers at the same time, or the PE router acts as a peer of the MP-EBGP to exchange cross-domain VPN Information, We need to disable this feature, use the command: no bpg default router-filter BGP Route refresh. Because the automatic route filtering feature is enabled on the PE router, when the configuration of the PE router changes, for example, if a new VRF is added or the existing VRF is deleted, the PE router's requirements for VPN routing may not be met in a timely manner. 4. BGP provides a routing refresh mechanism. When this feature is used, after a short period of time after the configuration is changed, the PE router will ask his MP-IBGP neighbor to re-Send the route update to get the lost VPN-IPv4 information, at the same time, we can also use this function, use the command clear ip bgp * vpnv4 unicast in, manually refresh the VPN route information. After you type this command, the router will send a route refresh request to all PE neighbors. Www.2cto.com
5. Route refresh and Automatic route filtering (AFR) can reduce the number of route information to be maintained by the PE router, but useless route information will still be transmitted in the network, instead, it is discarded only after arriving at a specific PE router. To avoid waste of network resources, BGP provides the open-source IP address library feature to notify its neighbors of its inbound route filters, this allows unnecessary routing information to be filtered out before arriving at the receiver PE router. The OPEN message is used to exchange the OPEN message in the session creation phase of the two PE routers. 6. Separate the MP-IBGP session between PE routers each PE router only needs to receive the route of the VPN of their service, therefore, we can drag different PE routers into an independent MP-IBGP Cluster Based on the VPN service object, the PE router in the same cluster to establish a full mesh MP-IBGP session.
7. Route reflectors and consortium in large networks, full mesh BGP sessions impose great limitations on network scalability, and the number of intra-domain MP-IBGP sessions can be reduced through route reflectors and consortium. 8. Configure an RT list on the route reflectors to specify a specific VPN route. configure a route reflector group so that the route reflectors can use the open packet forwarding rule to advertise its inbound route filters, in this way, the PE client router will not send useless routes to the route reflectors. The above is a brief introduction to the BGP maintenance mechanism of the lingke router. We recommend that you read this article. This article is from