We have already talked a lot about protocol converters, and at the same time have promoted the development of routing technology. Today, network construction has penetrated into various branches of the industry, such as the rural power information network of the power industry.
Generally, the use of Ethernet switches for networking by enterprises is mainly divided into two categories. One is to use protocol converters to convert private lines into Ethernet access switches; the other is to lease bare fiber directly. Specifically, the layer 3 switches selected in the third and fourth level networks can only be configured with simple dynamic routing protocols, simple policy routing, QoS, and simple access control functions. In fact, this location has More than this, the following issues should be noted when using Ethernet switch networking.
(1) Security
Now there are more and more viruses on the Internet, and the losses caused by network viruses are also increasing. It is unthinkable that the export equipment of a network does not have a certain firewall function. Low-end and middle-end switches basically do not have firewall features, and ACL access control functions are also very poor. For routers, even the lowest-end routers support state-based ACL control, which allows users to filter and configure according to the types and characteristics of network viruses. , You can also limit the maximum number of links per IP address to prevent anomalies.
(2) Business support flexibility
Some networks need to perform asymmetric access control on the servers inside the network, that is, they only accept access requests from outside but they cannot initiate requests to the external network. This helps prevent the server from being used as a hacking tool or cause leaks. The router can judge the status of the relevant session based on the ACL configuration, so that it can only enter or exit; and the low-end switch cannot complete this service because all the message forwarding is completed within the ASCI.
(3) Network expansion and sustainable development
The industry network must connect to the local e-government network now or in the future. At this time, in addition to the security of its own network, it must also consider the interoperability issues with other related industries and governments. L2TP, GRE, NAT and other features may be required. To achieve secure access to different private networks. In some industries, the network needs to run a variety of services with different security levels, and the requirements for resources are also different. At this time, in addition to QoS, individual services may need to be encrypted or even tunneled. In fact, all these functional switches cannot be supported, nor can they be supported through upgrades; routers basically support them.
(4) Network reliability
Some projects lease the operator's 2MB or n & TImes; 2MB private line, but use a protocol converter at the access location to convert the 2MB private line into Ethernet to access the layer 3 switch. The cost of the protocol converter itself is relatively low, and the reliability design cannot be perfected, which adds a point of failure to the network. In fact, protocol converter failure is one of the most common problems in project implementation.
(5) Comprehensive cost
In some projects, the links use 10 / 100MB bare fiber to realize the vertical link, and the switch network is used. Although the cost of purchasing network equipment is reduced in this way, the link cost is much higher than that of the ordinary 2MB dedicated line. Even if the operator now offers it at a relatively low price due to promotion, the bandwidth and services that users will enjoy in the future when the link is tight Will be greatly discounted.
(6) Link service
A dedicated line is used to link the vertical organization. The dedicated line enjoys an end-to-end full-line closed service. Users can see their network status at any time without assistance from the operator. When the link fails, it can be detected by the egress network device within a few seconds and immediately start the backup link automatically. The network interruption time is in seconds, and the service is generally not interrupted. If a protocol converter or switch is used, the link state change is blocked by the protocol converter. The user can only be aware of the interruption of the service. At this time, the fault cannot be located, so the time of the network interruption will be Calculated in hours. Based on the above analysis, we can see that the router is far superior to the three-layer switch in terms of function. Considering several aspects such as network management, line conditions, and network investment, we believe that:
(1) In the case of its own transmission fiber, because the stability of the transmission link is guaranteed, the use of switch networking can save investment, but it requires corresponding investment in network security and network management.
(2) In the case of leased operator dedicated lines, the use of router networking can save a lot of post-maintenance and management costs, which has a greater advantage than the use of switch networking.
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