A late collision occurs when two devices transmit at the same time, but due to cabling errors (most commonly, excessive network segment length or repeaters between devices) neither detects a collision. The reason this happens is because the time to propagate the signal from one end of the network to another is longer than the time to put the entire packet on the network, so the two devices that cause the late collision never see that the other?s sending until after it puts the entire packet on the network. The transmitter after the first "slot time" of 64 byte times detects late collisions. They are only detected during transmissions of packets longer than 64 bytes. Its detection is exactly the same as for a normal collision; it just happens "too late." Typical causes of late collisions are segment cable lengths in excess of the maximum permitted for the cable type, faulty connectors or improper cabling, excessive numbers of repeaters between network devices, and defective Ethernet transceivers or controllers. Another bad thing about late collisions is that they occur for small packets also, but cannot be detected by the transmitter. A network suffering a measurable rate of late collisions (on large packets) is also suffering lost small packets. The higher protocols do not cope well with such losses. Well, they cope, but at much reduced speed. A 1% packet loss is enough to reduce the speed of NFS by 90% with the default retransmission timers. That?s a 10X amplification of the problem. Finally, Ethernet controllers do not retransmit packets lost to late collisions
We have 3 identical switches configured by someone else and would like to claim some of the Gigabit ports(G1/G2/G3/G4) for use on servers. When we try to change the wiring and configuration, we run in to connectivity issues. Attached is a des...
This is actually a pretty cool feature, i didn't even know it existed until I was looking for a solution to advertise a subnet (prefix in BGP talk), only if a certain condition existed. This is exactly what conditional advertisements does
j ai une question j ai achete un routeur cisco 887VA-k9 , je le configuré avec la configuration ci- dessous
si je le lier avec mon pc portable sur l un de ses ports directement ça marche toute est bien ( la connexion internet + m...