Application of IBGP Routing Protocol in different network structures

The use of routes greatly expands the performance of the network. Next, we will analyze some characteristics of the IBGP routing protocol. Through the introduction of this article, we can understand the routing features in this regard. With the development of the network, ISP needs to connect to the INTERNET through multiple lines through different network providers to ensure network reliability. At this time, BGP is truly useful. In this case, the network usually has the following structures. II ,. The two network structures look similar. The network structure only adds a vro to eliminate the possibility of single point of failure (spof) generated by the router R1, but they are completely different when deploying BGP routes.

In, you only need to configure BGP on R1 and use R1 as the default gateway of other routers in the network, and use the route parameter Weight provided by the BGP routing protocol, adjust the distribution of Intranet traffic on two lines. In this way, lines can be backed up to each other and traffic distribution can be effectively adjusted.

Several Network Structures

In the figure, there are two routers with external routes. Generally, to ensure route consistency within the domain, you need to establish an IBGP connection between the routers R1 and R2 so that they can establish a consistent BGP Route table. In this process, you can also use the Local-Preference route parameter provided by the BGP routing protocol to optimize the route selection to control the distribution of data traffic on the route. However, there are two simple methods to tell other routers in the Network how to tell these external routes:

1. When the network structure is relatively simple, the network has no distribution layer, and the core layer is directly connected to the access layer. At this time, the access layer router cannot transmit a large amount of user data while meeting the performance requirements required to enable BGP. In this case, the Network Access Router is divided into groups only based on the traffic distribution. Different Groups Direct the default gateway to different border gateway routers.

This design can only be used as a temporary solution with imperfect network structure and low equipment performance. It cannot be used as a permanent solution. Because it often requires human intervention to re-divide the router group based on network traffic changes. Otherwise, the load on one vro is too heavy and the other is light, therefore, you cannot use device resources effectively. This design will face more problems when the number of interconnected lines increases.

2. The best way is to first establish and improve the network structure. The network structure should have the core layer, distribution layer and access layer. Use the IBGP routing protocol to inject external routes into the distributed layer routers, which are routers R3 and R4. Then, the distribution layer router is used as the default gateway of the access layer router in a certain region, and the load leading to the outside is evenly distributed to the routers of each distribution layer, reducing the pressure on a specific router.

This design is the final choice of ISP with increasingly complete network structure and expanding network scale.

Recently, CISCO has proposed a new idea of deploying BGP routing protocol from another perspective, using IBGP as the internal routing protocol to exchange routing information of users in the network. And enable the IBGP routing protocol on the access layer router of the network, and distribute the static routes pointing to the user to IBGP. This is mainly because the BGP routing protocol only updates the changed routes when the routes change. It does not re-calculate the SPF database like OSPF and ISIS. Therefore, BGP is used to reduce the convergence time and improve the network stability. However, when using this method, you should pay attention to the BGP requirements on the performance of the router. Avoid injecting external routes into the access layer router, resulting in a reduction in the working performance of the router.

To sum up, we briefly discuss how to deploy the BGP routing protocol on the ISP network. In fact, the key and advantage of BGP applications lies in its ability to control route information, so as to control and allocate data traffic. This is a very complicated task. It depends on the specific situation. I will not talk about it in this article. However, it is important to note that it is not feasible to rely solely on BGP methods to meet different practical needs. It must also work with the interconnection partners to achieve this purpose, because many parameters in BGP need to be agreed by both parties to take effect.