"Exchange" vs "routing" (2)    Switching is an important function to avoid the exchange cycle, which is involved in the STP (Spanning Tree Protocol, tree branches agreement). Tree branches function of the agreement is to avoid the network switches in the data frame transmission cycle. As in the figure below, if the network is redundant links, Spanning Tree Protocol is to elect Gen Switch (Route Bridge), then determine Taiwan and Africa each root root switches to switch between the path, finally, all the links on this path into home transponders (Forward) state. Redundancy Switch is a link between the rest of the link, home to occlusion (Block) state. Another important function is to switch VLAN (Virtual LAN, virtual LAN). VLAN There are three major benefits : Port segregation. Even in the same exchange, the port is not different VLAN communication. A physical switch can be used as a more logical switch. Network security. Different VLAN can direct communications to eliminate the radio insecurity. Flexible management. No need for users to change their own network and line ports, only the software configuration on it. VLAN port, or MAC address can be divided. Sometimes, we need to maintain a network switches are configured VLAN consistency. This requires interaction between VTP switches (VLAN Trunk Protocol, the backbone of the agreement VLAN) exchange VLAN information. VTP agreement only in the key port (Trunk Port), or switch between running the port.     Routing Router is the network connection device, it is important to choose the road. This function is the core of intelligent routers, it is managers from the configuration and the number of routing algorithm. The dynamic routing algorithm is divided into static routing is a special route, which is set by the administrator manual. Although the manual routing configuration can make all the normal operation of the network, but will also have some limitations. Network topology changes, would not automatically lead to changes in static routing, network managers must be involved. Routing is a default static routing, as well as set up by the administrator. The network has not found a goal in the routing table when the router and sent the information to the default router (gateway of last resort). The dynamic algorithm, as its name implies, is derived from Automatic Path Routing, it is often said that the RIP, OSPF, etc. are dynamic algorithm in 1974. Routing algorithm also can be divided into two DV and LS. DV (Distance Distance Vector) routing algorithm, the current path for the information transmitted to the adjacent router, adjacent routers will be adding its own routing table information. And LS (Link State, link status) algorithm to link state of all information to the router, the receiving routers use this information to build network topology, using graph theory and the Shortest Path First routing algorithm decision. By contrast, distance vector algorithm is relatively simple and link state algorithms are more complex and have more occupied by the CPU and memory. However, because the link is the state's own calculation algorithm, routing cycle is not so easy. DV algorithm is a typical representative of the RIP, OSPF and LS is the representative agreement. Four of the most common routing protocols, RIP, IGRP, OSPF and EIGRP. RIP (Routing Information Protocols, Routing Information Protocol) is the most widely used and the distance vector protocol, it is by Xerox (Xerox) in the development of the 1970s. At that time, the RIP is XNS (Xerox Network Service, Xerox Network Services), part of the cluster agreement. TCP version of the RIP is the improved version of Xerox agreement. RIP is the greatest feature of both Principle or distribution method is very simple. RIP routing calculation based on hops, and the regular updates sent to the neighbor routers. CISCO IGRP is the exclusive agreement, the Cisco routers to achieve. It also falls distance vector types of agreement, and RIP are common in many places, such as radio, etc. updated. RIP, and the biggest difference in its performance measurement, load balancing and other aspects. The Weighted IGRP support multi-path load balancing, network bandwidth can be more reasonable to use. In addition, only with the use of hops as a measure based RIP, IGRP to use a variety of parameters, which constitute a composite of the degree of money, and these factors may include : bandwidth, delay, load, reliability and MTU (maximum transmission unit), and so on and so forth. The OSPF protocol is the development of the late 1980s and early 1990s to become industry standards, is a typical example of the link status agreement. The main features include : OSPF support VLSM (Variable Length Subnet the cover?), Rapid convergence, bandwidth occupancy rate low and so on. OSPF protocol between the neighbors exchanged link status information for the routers to establish link state database (LSD), followed by routers based on the information in the database using SPF (Shortest Path First, Shortest Path First) routing algorithm, the choice of path bandwidth is the principal basis. IGRP EIGRP is the enhanced version, it is Cisco's proprietary routing protocol. Used to update the proliferation EIGRP (DUAL) algorithm, to the extent that it and similar distance vector algorithm, but with a much shorter time and the convergence of better operability. As the expansion of IGRP, EIGRP supports a wide variety of routing protocols, such as IP, IPX, and AppleTalk, etc.. IP environment in the operation, IGRP and EIGRP smoothing can also link, as their measurement is the same. Four more are routing protocol domain routing protocol, they usually use in the internal autonomy. When the link between the self-government system, often used as BGP (Border Gateway Protocols, the border routing protocol) and EGP (External Gateway Protocols external routing protocol), the Inter-Domain Routing Protocol. Internet use in the inter-domain routing protocol BGP is fourth. Convergence routing algorithm is an important issue faced by choice. Convergence refers to the time from the network topology changes in the structure of the network are informed of all relevant path for this change, and to make corresponding changes in the time required. The shorter this time, the network changes to the entire network of smaller disturbances. Convergence routing cycle will lead to the emergence of a long time. Several areas in the above routing algorithm, the convergence of a relatively long time RIP and IGRP are ;OSPF to the minutes of magnitude shorter, dozens of convergence can ;EIGRP shortest network topology changes, a few seconds can achieve a state of convergence. EXCHANGE Campus Network Park is the traditional network switches routers plus structure. Shown in the following figure, the internal network switches for the transmission of classified VLAN to ensure the security and flexibility of the second floor, complete network routers and data transmitted between the addressable work. Usually, the performance of the road is worse than switches, routers because of the look-up table is based on transmitting software, hardware and switches can be achieved through the transponder. But in the traditional campus network, the router will not become a network bottleneck. Because 80% of the volume of data in the internal communications network, only 20% of remote access to data is done in other words, most of the information is not read after switching router. This is the traditional network model 80/20 flow. In recent years, because of the rise of Internet computing model, the application was centralized management, rather than scattered in various departments as in the past the network, network traffic model park has undergone a drastic change. The visit is a lot of long-distance network, which is to go through the router. This was called the new 20/80 flow model. Therefore, routers become network bottlenecks. To solve the technical problems, manufacturers developed a three-tier network switches, also known as Routing Switch. It is the performance of traditional switches and routers smart combination. Routing devices still trails completed, but the road was the result of the election to retain its own Routing Switch caching. Thus, a stream of data packets through a router, all subsequent data packets transmitted directly from the switch Lookup. Benefited from the hardware forwarding, wire-speed routing layer 3 switches can be done, as shown in the following figure. Many manufacturers to produce the three-tier exchange itself is a combination of switches and routers, Cisco's Routing module matching 5000,5500,6500 series of switches can achieve three functions. Thus, the park is an internal network switches, and layer 3 switches to the game, the entire campus network to adapt to the new exchange flow model, completely unlike the traditional network router bottlenecks, which has greatly enhanced the efficiency of the network. Meanwhile, routers and no unemployment, is still being used in remote connectivity, dial-up interviews occasions. In this paper, the first part of a review of the network hierarchy, followed by the traditional routing and switching on the principles cited in the park network routing and switching how to combine the advantages that best meet the users of model. Routing, exchange and the exchange of routing paper is the main three issues. Space limitations, the agreement would not go into the specific, sometimes, to understand the processes and agreements specific equipment, such as Cisco's routers and switches, the theory is helpful in understanding the network.         "Exchange" vs "routing" (2) The person is tough "Exchange" vs "routing" (2) Thanks. "Exchange" vs "routing" (2) Thx "Exchange" vs "routing" (2) "Port segregation. Even in the same exchange, the port is not different VLAN communication. "Vlan seems to be divided by other agreements visits ineffective, and not different vlan, can of ping, ftp, please give pointers "Exchange" vs "routing" (2) Xiongtai thank you! ! ! ! ! 1 "Exchange" vs "routing" (2) Thank you for your excellent suggestion that rewarding. "Exchange" vs "routing" (2) VLAN mean completely different physical isolation, no communication protocol would be useless. Landlord hard! Hard ~! Based on the second floor of the exchange MAC, routing based on a three-tier TCP, VS Why? ? ? A top A labor, Read the rest Goes --> This is not like 80/20, but the 20/80 Em02 : : China and the self. . Although somewhat understood. . But to support a roof! ! Yes, received the. Yes, I would like to thank lz. Hard --> PING通 not completely isolated [ Closed window ]