Design and configuration realization of Campus network dual-outlet

Campus network is the infrastructure of information construction in colleges and universities, and is an important platform for information and modernization of teaching and research management. The campus network of most colleges and universities has a few years ' history since it was first built. When first built, it is generally rented a DDN line connected to the Chinese education and Research computer network (CERNET). Because the Chinese educational Research network differs from the general telecom-level operation network, there is no very abundant line and equipment redundancy, it is possible to have a single point of failure, which has certain influence on the stable operation of the campus network. At the same time, through cernet access to other common network such as chinanet, gbnet speed slow. With the increase of users of campus network and the deployment of various network applications based on campus networks, it is required that the export of campus network has higher network bandwidth, the original single cernet export has not been satisfied, and it is necessary to enlarge the bandwidth further, Through the local network service provider (ISP) to open up the second export connected to the Internet is a better solution, many schools have adopted a network of education and Telecommunications (or unicom, railcom, etc.) the second export of dual export program, can retain education network resources, while increasing the bandwidth, Increases the speed with which Internet resources are accessed.

Each school uses different technology to achieve dual exports, but basically the idea is the same: access to education network resources and mail flow Education network export, for users to access the Internet, take the second exit. In this way, on the one hand, improve the campus network of export redundancy, increase the stability of the campus network, on the other hand, also solve the campus network to visit the slow speed of the problem, at the same time, effectively reduce the education network of International traffic, reduce network operating costs.

The second outlet from the connection mode, you can use DDN line, ISDN, ADSL and other technologies, can be selected according to the requirements, in this article will not be discussed.

First, dual export solutions

On the basis of the original Cernet access link, our school has opened a second export through telecommunications. And the increase of campus network export lines, theoretically improve the network bandwidth, but if not adjust the original network system structure, its effect can not be reflected. For this program, we have the following requirements:

(1) Client IP address settings are not affected, that is, do not have to reset the address can be normal access to the Internet;

(2) When the client visits the website of Educational Research Network, export line cernet, visit other sites, take China Telecom line export.

(3) Solve the problem that the users of external public network visit the homepage of our school campus network too slowly.

(4) The mail in the campus network goes cernet line.

(5) As much as possible to save the campus network adjustment, transformation of investment.

Cisco Catalyst 6509 Switch is the core of our campus network switch, SSR1 is the education Network access equipment, SSR2 is the second export of telecommunications access equipment through the Cisco Catalyst 6509 switch To configure static routes and policy routes, All traffic to the authorized server and mail is SSR1 to the education network, and all other traffic is SSR2 to the telecom outlet. At the same time, NAT technology is used on the SSR2, so that the limited IP address can satisfy the demand of the concurrent access of the campus network, and the safety factor is also improved correspondingly.