How to use multiple vro protocols in a network

Why are we always talking about router protocols? For the construction of a network, the use of the router protocol is directly related to the various performance and indicators of the network. So this is very important. With the complexity of the network structure, the use of a single Router Protocol can no longer meet the needs. Therefore, there will be a variety of router protocols in a network, so how to diversify the router protocols? There are many ways to implement multiple vro protocols in a network. Sometimes, these vro protocols do not even know the existence of other protocols (called "Night ships "), there is no information exchange between them. This is usually the case in complex transplantation. Another extreme situation is completely dynamic, for example, after "mutual redistribution" is configured, the "Optimal Method" is located between the two cases "｡

In my last introduction, I discussed the use of Intranet gateway and external Gateway (IGP and EGP) at the same time. In this article, I will focus on the interaction of these router protocols, the following describes in detail how to implement these vro protocols ｡

At the beginning, you must clearly understand what you want to achieve, because these two identical Router Protocol sets have two completely different usage methods. The difference depends on whether your network is a switching network. That is to say, do you want to allow data packets from both the source and target addresses to pass through your network? If you are an Internet Service Provider (ISP), the answer is probably "yes ", if you are a formal enterprise, the answer is usually "no". The answer to this question will guide you in design principles on ease of management. Specifically, IP subnets released through the exchange network are usually very active, and it is unrealistic to configure each IP router statically. On the other hand, the enterprise's network may be greatly changed internally, however, their address space does not change frequently ｡

For enterprise network administrators, this option usually comes down to whether it is easy to configure mutual redistribution between their intranet gateway and external gateway, and to control the network through the access list, or is it easy to use network declarations to configure the Intranet gateway and external gateway. Generally, you do not select Network declarations because the network declarations are static. This is indeed true, however, the access list of the driver route chart is also static, so mutual redistribution is no longer dynamic. Mutual redistribution in the enterprise network is usually not a good method ｡

In the network declaration, although the command itself is static, the network Declaration is very simple and easy to understand, so it can lead to very definite behavior, without having to guess what your network will do. But many network administrators are not aware that network declarations are dynamic to some extent, because even if you make a declaration, the route will not be published unless it already exists in the routing table (that is, the router has an IGP path, or Static Routing or connected interfaces), so if the IGP route goes out, then the BGP Route goes out ｡

Even so, another popular option is one-way redistribution. This is useful when you have multiple paths to exit the network, however, you need to make a good balance between dynamic and controllability. Finally, remember that using two vro protocols helps you make informed decisions at EGP, instead of sending 120,000 routes to your IGP. filter as many routes as possible and the default items are often not perfect ｡