Ten questions about Routing technology by IELAB NETWORK
Dear friends, the next question may be a bit difficult, are you ready?
- What does the dynamic routing protocol do?
This time let’s solve the first more difficult problem-routing protocol. I believe that beginner students will always have more or less problems with the learning of routing protocol. Now, let’s do it a little bit.
First of all, what are the most important functions of routing protocols? —–Of course, it is necessary to be able to calculate routing information!
Therefore, for each routing protocol, how to calculate routing information, what method to use for calculation, that is, the algorithm adopted by the routing protocol, the parameters selected by the metric, and how to calculate it, are ten minutes important. Different routing protocols also mean different ideas for solving problems. Naturally, the parameters selected for the metric used to judge the path are also different.
What is the second basic function of the routing protocol? —- Ability to collect routing information, and to transmit routing information or LSA. So, what is the second aspect of the routing protocol that needs attention? It is the interaction of data, including the content involved: who interacts with whom, how to interact, and what to use. This problem generally corresponds to the way that neighbors exchange data and the type of data packet interaction between different routing protocols. DV-type routing protocols generally exchange routing information, while LS-type routing protocols are special, interacting with LSA or LSP, and ultimately, the interaction forms LSDB, which is a database. Eventually, LS routing protocols such as OSPF and ISIS will run corresponding algorithms based on LSDB to calculate the final routing information. This is what we mean by “measure neighbor database” in our formula
The last more important content of the routing protocol is what we call loop protection and update security. General routing protocols support MD5 authentication and the principle of loop protection. In the DV routing protocol, the horizontal split and the LS routing protocol pass itself. The algorithm calculates an acyclic tree structure and produces the final calculation result. This is what it means to update security and loops.
- What is DV routing protocol?
Distance vector routing protocol, that is, DV routing protocol. A distinctive feature is: the rumored routing protocol and the limitation of the number of hops. The so-called number of hops is to limit the number of nodes experienced during the transfer process and the transfer range.
Taking RIP as an example, the transmission range is limited to 15 hops, which is not suitable for large-scale networks. In a large-scale network environment, this type of protocol will generate a large amount of traffic when learning routes and maintaining routes, and consumes too much bandwidth. And the routing information is passed during the interaction.
- What is LS routing protocol?
Link state routing protocol, that is, LS routing protocol. Different from the DV routing protocol, it transmits LSA or LSP. The SPF algorithm used by itself is based on a loop, which can fundamentally solve the loop problem. However, due to its complexity, the router requires more CPU resources. It can discover broken links or newly connected routers in a shorter time, making the convergence time of the protocol shorter than that of the distance vector routing protocol.
- When is the route re-advertisement performed?
What is route redistribution, we have previously explained. General route import will not cause routing loops. So when will the routing protocol be introduced? It is generally configured on routers that are responsible for learning routes from one autonomous system and then broadcasting to another autonomous system. In addition, in new and old networks or networks where devices from different manufacturers are mixed and matched, it may be necessary to introduce or re-release routes. However, the two-way re-release itself will cause routing feedback, loops, and sub-optimal paths. Therefore, a strong understanding of routing control is required to solve two-way re-release. During the deployment process, we should try to avoid designing the network as a two-point two-way or multi-point two-way re-release structure.
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