1. There are four dynamic routing protocols:
1. RIP (Routing Information Protocol).
2. OSPF (Open Shortest Path First).
3. ISIS (Intermediate System to Intermediate System).
4. BGP (Border Gateway Protocol).
two. What is RIP
Introduction to
RIP RIP is the abbreviation of Routing Information Protocol (Routing Information Protocol), it is a relatively simple Interior Gateway Protocol (Interior Gateway Protocol).
1. The basic principle of
RIP RIP is a protocol based on the Distance-Vector algorithm. It uses Hop Count as a metric to measure the distance to the destination address.
In a RIP network, by default, the number of hops from a device to the network directly connected to it is 0, the number of hops from a network reachable through a device is 1, and the rest can be deduced by analogy. In other words, the metric value is equal to the number of devices from the local network to the destination network. To limit the convergence time, RIP specifies that the metric value is an integer between 0 and 15. The number of hops greater than or equal to 16 is defined as infinity, that is, the destination network or host is unreachable. Due to this limitation, it is impossible for RIP to be used in large networks.
three. What is OSPF
OSPF is a link state routing protocol based on SPF algorithm.
The above picture shows the working process of the OSPF protocol when a new router is added to an OSPF area. If you can describe this picture in great detail, you can basically master the working process of the OSPF protocol.
First of all, everyone must be clear that a router running the OSPF protocol will eventually store three tables: neighbor table, topology table, and routing table. The following uses the process of generating these three tables as a clue to analyze what changes have taken place in the router during this process, so as to illustrate the working process of the OSPF protocol.
4. What is the ISIS
intermediate system to the intermediate system? IS-IS running in CLNP and IP networks is called integrated ISIS. Based on the
data link layer and multicast update, the multicast MAC is 0180-C200-0014 and 0180-C200-0015.
IS-IS and OSPF have many similarities and differences, but I feel that the difference is not too great. Some people say IS-IS is simpler, but I think IS-IS is orthodox. Of course, this varies from person to person. . . . . .
First, briefly describe the similarities between OSPF and IS-IS:
1. Both maintain an LSDB and use the SPF algorithm to calculate the optimal path to the target network.
2. Both use hello packets to establish and maintain adjacency relationships
. 3. Both are used for The concept of constructing a hierarchical network area
4. All are classless routing protocols
5. In a broadcast-type multiple access network, a designated router needs to be selected
6. Support authentication
5. What is BGP?
BGP is the abbreviation of Border Gateway Protocol, which is a routing protocol used to connect independent systems on the Internet. BGP is mainly used for interconnection between Internet AS (autonomous systems). The main function of BGP is to control the propagation of routes and select the best route. Compared with the traditional dual-IP dual-wire technology, the computer room using BGP technology can select the optimal path for the server's upstream route and downstream route, so it can truly realize high-speed single-IP high-speed access, and BGP has redundant backup, Eliminate the characteristics of loops, when one line has a problem, it will automatically switch to other normal lines.
The BGP computer room solves the problem of north-south intercommunication between users to a certain extent, improves the user's access speed, and achieves the effect of single-IP dual-line using the BGP protocol. The solution is to directly map the IP of one line to the IP of the other line through the BGP protocol. When visitors browse your website, they will automatically select the line with the fastest access speed according to the actual situation, so that users of all operators can Achieve the best access speed.
1. The server only needs to set an IP address, and the best access route is determined by the backbone router on the network according to the route hop count and other technical indicators, and will not occupy any system resources of the server. Both the upstream route and the downstream route of the server can choose the optimal path, so it can truly realize high-speed single-IP high-speed access.
2. Because the BGP protocol itself has the characteristics of redundancy backup and elimination of loops, when IDC service providers have multiple BGP interconnection lines, they can realize mutual backup of routes. When one line fails, the route will automatically switch to other lines.
3. Using BGP protocol can also make the network have strong scalability. IDC network can be interconnected with other operators, and single IP multiple lines can be easily realized, so that users of all interconnected operators can access quickly. This is incomparable with dual IP dual lines.
