The test of SP CCIE V5.0 has begun, but Cisco announced that it will continue to close CCIE test rooms around the world in May. We can’t predict how long this will last. But there is one thing for sure that the test of SP CCIE will have the content of MPLS l3vpn. If you don’t understand it, you can understand it after reading the following content
MPLS L3 VPN is perhaps the most widely used MPLS. The popularity of MPLS is also related to the wide deployment of MPLS L3 VPN. What is MPLS L3 VPN?
VPN (virtual private network): virtual private network. Different from the physical private network, the virtual private network makes users not need the special physical circuit, but carry out the propagation of private network services on the public infrastructure, so as to achieve the function of the private network.
L3 VPN: a VPN implementation mode, which is built on the L3 network, or it transmits L3 packets.
MPLS L3 VPN: L3 VPN is built on the MPLS network.
MPLS l3vpn is a PE based l3vpn technology in the VPN solution of service provider. It uses BGP to publish VPN route on the backbone network of service provider, and uses MPLS to forward VPN message on the backbone network of service provider. MPLS l3vpn has flexible networking mode, good scalability, and can easily support MPLS QoS and MPLS TE, so it has been used more and more.
MPLS l3vpn model consists of three parts: CE, PE and P.
CE (customer edge) device: user network edge device, with interface directly connected to sp (service provider). CE can be a router or switch, or a host. CE “senses” the existence of VPN and does not need to support MPLS.
PE (provider edge) Router: the service provider edge router is the edge device of the service provider network, which is directly connected to the CE of users. In MPLS network, all the processing of VPN takes place on PE.
P (provider) Router: the backbone router in the service provider network, which is not directly connected to CE. P device only needs to have basic MPLS forwarding capability.
The division of CE and PE is mainly based on the management scope of SP and user, and CE and PE are the boundaries of the management scope of both. CE device is usually a router. When CE establishes an adjacency relationship with PE directly connected, CE publishes VPN route of this site to PE, and learns the route of remote VPN from PE. BGP / IGP is used to exchange route information between CE and PE, and static route can also be used. After PE learns VPN routing information from CE, it exchanges VPN routing information with other PE through BGP. The PE router only maintains the routing information of the VPN directly connected to it, and does not maintain all VPN routes in the service provider network. P router only maintains the route to PE, and does not need to know any VPN routing information.
In the basic MPLS l3vpn network, the issuance of VPN routing information involves CE and PE. P router only maintains the routing of the backbone network, and does not need to know any VPN routing information. PE router only maintains the route information of VPN directly connected to it, not all VPN routes. Therefore, MPLS l3vpn network has good scalability. The publishing process of VPN routing information includes three parts: local CE to entry PE, entry PE to exit PE, and exit PE to remote CE. After the completion of these three parts, reachable routes will be established between local CE and remote CE, and VPN private network routing information can be published on the backbone network.
1. Routing information exchange from local CE to entry PE
After CE establishes an adjacency relationship with the PE directly connected, the VPN route of this site will be published to PE. Static routing, rip, OSPF, IS-IS, or ebgp can be used between CE and PE. No matter which routing protocol is used, CE publishes standard IPv4 routing to PE.
2. Routing information exchange from entry PE to exit PE
After PE learns VPN routing information from CE, it adds RD and VPN target attributes to these standard IPv4 routes to form vpn-ipv4 routes and store them in VPN instances created for CE. The entry PE publishes the vpn-ipv4 route to the exit PE through MP-BGP. According to the export target attribute of vpn-ipv4 route and the import target attribute of VPN instance maintained by itself, the export PE decides whether to add the route to the route table of VPN instance. IGP is used between PE to ensure internal connectivity.
3. Routing information exchange from export PE to remote CE
There are many ways for remote CE to learn VPN routing from export PE, including static routing, rip, OSPF, IS-IS and ebgp, which are the same as the routing information exchange between local CE and import PE.
It’s very important to study this content and prepare for CCIE. The price of our SP CCIE is the most favorable before Cisco does not open the examination center. We think it will be the best opportunity for all written examinations and lab purchases at this time. Because it’s a discount that has never been offered.
IE-LAB provides valid materials(accurate dumps) to help you pass your CCIE. For the written, we have valid workbooks that cover all real exam questions. You can easily pass the exam, usually 7 days’ preparation in enough. For the Lab exam, we will offer valid workbooks（real exam）, rack which is the same as real exam, one to one support, professional tutor and timely update.
This article is exclusively published by James from IELAB.NETWORK and cannot be reproduced without permission.
visit us: http://ielab.network