China, some network troubles arrange and check, it is often more relaxed to solve because of having very obvious phenomena; But there is a trouble very strange of some networks, ping tests obviously everything is normal, but the transmission speed of the network is unusually slow, as to this kind of special trouble phenomenon, we must want, set out, rank, consult, could orientate the trouble reason, solve the trouble phenomenon in an all-round way a bit more. Look, I surf the Net unstable trouble phenomenon one once, through many to rank, consult a bit, in an all-round way, unexpectedly find this trouble is not enough to cause because of the memory capacity of the router, because this kind of trouble factor seldom appears, it is very apt to take more detours during the process of arranging and checking this trouble, this text reduces the exclusion course of this trouble out now, exchange for every friend’s reference!
A unit subsidiary of mine, include these departments of technology department, engineering department, banking department, sales department altogether, probably there are about 20 of ordinary computers in each department, all ordinary exchangers of BayNet brand through each department of these computers are connected to CISCO router of the LAN, each department has one’s own independent sub network of work, they can’t visit each other each other, the ordinary computer can only share, exchange in the same sub network of work; However, unit file server, printing server, Web server,etc., all connect to the router port directly, all computers of the department can visit directly, and they still can visit Internet network through the router. In order to guarantee operation safety of LAN network, the network administrator of the subsidiary is still between router and Internet network, erect heaven and melt the letter hardware fire wall, to control and monitor the whole unit behavior of access to netwoks safely.
At ordinary times, ordinary computers in each department can surf the Net normally, and these computers are in Intranet of each department, can share, exchange and visit each other; Meanwhile, because of the need of work, Web server which the Internet user of each department will nearly visit the company every day, inquire, download some internal information of the company from it. However, recently, the network administrator has found the users of each department are while visiting Web server or Internet networked, will often present the unstable phenomenon of surfing the Net, that is to say that it is very fast to sometimes surfs the Net, it is very slow to surf the Net sometimes, will even appear and can surf the Net for a moment, trouble phenomenon that can’t surf the Net for a moment.
Arrange the trouble of checking
Because this kind of trouble phenomenon exists in each department, the network administrator estimates this kind of phenomenon does not have any relation with the systematic one’s own establishment of ordinary customer end mostly, what factors the Net surfing stability influencing the whole LAN there is that on earth? The network administrator has pondered again to the trouble phenomenon that analyzes, think few laws can be followed when this trouble takes place, it surf the Net have the slow when having quickly,network can at can have had sometimes,irregular troubles such phenomenon is caused by network virus in the LAN probably, in fact a lot of network troubles made of virus are displaying so and having no law. Unstable trouble factor that the virus of the network really causes surfing the Net that if confirm, it is unusual that then the virus of the network will probably cause the flow of port data of some important communication in the network; According to such analysis, the network administrator decides to enter router backstage supporter’s system of the LAN by the log-in of super terminal procedure first, then utilize this systematic scanning attached to diagnose the function, find the flow of data of each exchange port is not very large in the LAN, it means the virus of the network has not led to the fact the bottleneck phenomenon takes place in the data transmission of the important port. Even so, the network administrator worries a bit, require the staff members of each department, the network virus logging in in the LAN immediately defends the server, install and upgrade the antivirus software of network, utilize it to carry on virus once and check to the computer system of one’s own department that kill operating, but such efforts does not make result any, it seems LAN surf the Net unstable trouble phenomenon with virus of the network have nothing to do.
Consider the network administrator has already scanned the flow situation of each exchange port before, have not seen that there is an unusual situation, it means that there is a port bottleneck phenomenon of important data in the LAN, that is to say that the unstable trouble phenomenon and port bottleneck factor do not matter either to surf the Net. Meanwhile, the important flow of data of exchanging the port is normal in size, reflected too that there is radio storms or network cycle phenomenon in the LAN, because these phenomena exist, we should can see that exchanging output broadcast Bao Da of the port importantly littly should increase constantly, but there is not the fact, this means it is caused that unstable trouble of surfing the Net is not broadcast the storm or network cycle phenomenon by the network.
After getting rid of the port bottleneck factor, cycle factor of the network, broadcasting the storm factor and network virus factor tentatively, the network trouble can’t be dispelled, network administrator’s extremely annoyance that this let. Referring to and surfing the Net the unstable trouble in the past, the network administrator may be regarded as the insecure factor of network link subconsciously, but now he does not suspect on the factor of connecting of the network by any chance, because the unstable trouble of this kind of Net surfing nearly will appear in the sub network of work of each department, it is insecure in network link since not really is it,then either can not LAN more last phenomena insecure at the same time all computers.
May network equipment one’s own performance unstable, cause, surf the Net unstable phenomenon? Associate it with summer, because some apparatus does not dispel the heat bad, cause oneself working performance drop, often surf the Net and lose the line or slow phenomenon of pace, infer it may be that a router or exchanger in the LAN is overheated for this network administrator, cause one’s own working performance to be unstable. Then, the network administrator comes to the computer lab of the company immediately, has observed the signal lamp states of the router, exchanger first, find everything normal, while touching the surface temperature of the apparatus with hands, not aware either that there is any unusual phenomenon.
On condition that have no alternative, the network administrator decides the system of fire wall that log-in enters the LAN, look over some operation status informations among them, see what doubtful place it is. Let him feel very unexpected thing appears, the network administrator sees unexpectedly it is the communication traces of 0.0.0.0 host computers to record a lot of IP addresses in the LAN fire wall, what kind of host computer address is that 0.0.0.0 on earth? Search for through surfing the Net, the network administrator finds this address is that Windows system describes the address of all unknown IP, including the address that the network card apparatus is obtained through dhcp way, IP address of pppoe, and other IP addresses that not this machine appoint; In addition, 0.0.0.0 addresses represent the whole a network, it can help the router to send the way and is undertaken by ones that can’t inquire in the form. If set up the route of the whole a network, the way is undertaken by ones that can’t inquire in the form to the route that will all send the whole a network. Through the description above, the network administrator thinks this address is actually an address not existing, then on earth what factor let Extranet carry on communication with a host computer not existing at all in the LAN ceaselessly? If it is really that Extranet and 0.0.0.0 addresses are carrying on communication constantly, then the data of Extranet are chartered how to enter in the LAN, because the fire wall in the unit LAN has already set up, prevent those from using host computer of the obvious false address to carry on communication?
Solve the trouble
Further looked over the record of fire wall, the network administrator sees that has not operated any communication in 0.0.0.0 addresses, has it been intercepted by the fire wall that they are true? It will be that the LAN has been attacked illegally, attack and wrap up it after entering Intranet, disguise their IP addresses into 0.0.0.0 addresses? But the fact situation is, that IP address has not operated any communication for the host computer of 0.0.0.0, then to attack the bag illegally even trying to attack Intranet, have not succeeded either, thus the unstable phenomenon that it will not even cause and surf the Net; For this reason, the network administrator concludes that there is not thing which Extranet attacks, 0.0.0.0 addresses must come from the inside of LAN, then how on earth was this impossible IP address produced? Surf the Net and consult relevant information again, when the network administrator finds memory capacity of some important network equipment is not enough, may abandon some data and a pack of information in communication, cause some Net surfing contents to be unable to put together effectively, it is apt to produce some 0.0.0.0 addresses at this moment.
Analyze, the network administrator infers 0.0.0.0 addresses will probably come from Intranet according to theory described above, and this address will not probably be enough to cause because of the exchanger in the LAN or memory capacity of router. The unstable trouble exists in each department because of surfing the Net, the network administrator estimates the question is lain in on the relevant router apparatus with sub network of a job mostly, then plan to enter router backstage supporter’s system of the LAN through the log-in of long-range connection way this time, in Telnet, the network administrator feels the log-in pace is obviously obtuse, it seems the apparatus of the router has really gone wrong. Later, he used Console to control the line to connect to router backstage supporter’s system directly, while looking over its memory’s performance, find the memory of this apparatus is really insufficient in capacity, very obvious in surfing the Net the peak, the memory capacity of the router shows even more insufficiently, the incoming road is unable to transmit the information of the data normally naturally by the device if so, this is exactly an unstable reason of surfing the Net in each department too.
After finding the trouble reason, the network administrator restarts a router system immediately, find the Net surfing state of each department has returned to normal again immediately, while controlling the memory capacity of the router again at this moment, find this memory occupancy become heavy constantly too, seem that really solve the problem, need to upgrade the apparatus of the router, otherwise after a while, and also has restarted the router system.