Types of Dynamic Routing Protocols

The routing protocol is used to exchange routing information between routers. With the continuous development of network technology, the more complex the network, and the emergence of new routing protocols. Through the routing protocol, the router can dynamically share information about the remote network. The routing protocol can determine the optimal path to each network, and then add the path to the routing table. The dynamic routing protocol can automatically detect remote networks. As long as the network topology changes, the routers exchange route information with each other, you can also find the backup path when the current network connection fails. What are dynamic routing protocols?

(1) RIP Routing Protocol

The RIP Protocol was originally designed for the Xerox parc common protocol of the Xerox network system and is a common Routing Protocol in the Internet. RIP uses the distance vector algorithm, that is, the router selects routes based on distance, which is also called the distance vector protocol. The router collects all the different paths that can reach the destination, and stores the path information about the minimum number of sites to reach each destination. All other information except the Optimal Path to the destination is discarded. At the same time, the router also uses the RIP Protocol to notify neighboring routers of the route information. In this way, the correct routing information gradually spreads to the entire network.

RIP is widely used, which is simple, reliable, and easy to configure. However, RIP is only applicable to a small homogeneous network, because it allows a maximum of 15 sites, any more than 15 sites are marked as inaccessible. In addition, the route information broadcast once every 30 s by RIP is also one of the important reasons for the network broadcast storm.

(2) OSPF Routing Protocol

0SPF is a link-based routing protocol. Each router needs to send link status broadcast information to all other routers in the same management domain. All interface information, all measurements, and other variables are included in the OSPF link status broadcast. A vro with 0SPF must first collect the relevant link status information and calculate the shortest path to each node based on certain algorithms. The Distance Vector-based routing protocol only sends route update information to its neighboring routers.

Different from RIP, OSPF divides an autonomous domain into zones. There are two types of routes to be selected: when the source and destination are in the same zone, the intra-zone routes are used; when the source and destination are in different regions, the interval routing is used. This greatly reduces network overhead and increases Network stability. When a vro in a region fails, the normal operation of vrouters in other regions in the autonomous region is not affected, which also facilitates network management and maintenance.

(3) BGP and BGP4 routing protocols

BGP is an external gateway protocol designed for TCP/IP Internet. It is used between multiple autonomous domains. It is neither based on pure link state algorithms nor pure distance vector algorithms. Its main function is to exchange network accessibility information with BGP of other autonomous domains. Each autonomous domain can run different internal gateway protocols. The bgp update information includes the paired information of the network number/autonomous domain path. The autonomous domain path includes the autonomous domain string that must pass through a specific network. The update information is transmitted over TCP to ensure the transmission reliability.

BGP is still evolving to meet the growing needs of the Internet. In the latest BGP4, similar routes can also be merged into one route.

(4) IGRP and VPN protocols

The earlier IGRP protocol was invented by Cisco and is a dynamic routing protocol based on the distance vector algorithm. The Enhanced Interior Gateway Routing Protocol is an Enhanced version of the IGRP Protocol. It belongs to the dynamic Internal Gateway Routing Protocol and still uses the vector-distance algorithm. However, its implementation is much better than IGRP, and its convergence characteristics and operation efficiency are significantly higher than IGRP.

Its Convergence feature is based on the DUAL (Distributed Update Algorithm) Algorithm. The DUAL algorithm makes it impossible to form a loop in route computing. Its convergence time can rival any other existing routing protocols.

The main differences between Enhanced IGRP and other route selection protocols include: Fast Convergence, support for variable-length Subnet Mask (Subnet Mask), local update, and multi-network layer protocol. The router that executes the Enhanced IGRP stores all its adjacent Route tables so that it can quickly take advantage of various alternative Routes ). If there is no proper path, Enhanced IGRP queries its neighbor to obtain the required path. The Enhanced IGRP query is terminated until a proper path is found. Otherwise, the query continues.

The network type of any subnet mask is used to aggregate all the route entries in the network. This reduces the transmission of route information and saves bandwidth. In addition, you can configure the VPN protocol to support route aggregation on the bitwise border router of any interface.

No periodic update is performed on the network. When the path measurement standard changes, Enhanced IGRP only sends the Partial Updates information. The transmission of partial update information is automatically limited, so that only the routers that need the information are updated. Based on the above two types of performance, Enhanced IGRP consumes much less bandwidth than IGRP.

With the enhanced internal gateway routing selection protocol, a vro maintains a copy of its route table of the neighboring vro. If it cannot find a route to its destination from these tables, it asks its neighboring routers for a route and they take turns asking about their neighboring routers until they find a route. To keep all routers in the neighboring vro status, each vro periodically issues a "handshake" packet. A router that does not receive the "handshake" packet within a certain period of time is considered invalid.

Static Routing is a route table manually set by the network administrator. The advantage of Static Routing is fast network addressing, which is suitable for network systems with few changes in the network.

Dynamic Routing means that the route table is not manually set by the network administrator, but is automatically generated by the router through port address learning. Dynamic Routing is highly adaptable to network changes and is suitable for network systems with large network environment changes.

In a vro, you can configure static routes and one or more dynamic routes at the same time. The route tables they maintain are provided to the forwarder, but the table items in these route tables may conflict. This conflict can be solved by configuring the priority of each route table. Generally, static routes have the highest priority by default. When other route table items conflict with them, they are all forwarded by static routes.

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