tailieunhanh - syngress sniffer pro network optimization troubleshooting handbook phần 2

khi tôi được gọi đến để điều tra một sự xâm nhập tại một trường đại học lớn. Một người nào đó phát hiện ra một cracker mật khẩu chạy trên một trong những máy chủ của họ, mà kết quả trong công ty bảo hiểm bảo mật lớn bay tôi vào mạng riêng của trường đại học là một mớ hỗn độn | 38 Chapter 1 Introduction to Sniffer Pro frames. Although retiming frame delivery slows overall network performance it is often preferable to data loss. If an active hub receives a weak signal it regenerates the signal before broadcasting it. Some active hubs also provide additional diagnostic capabilities. Note Intelligent hubs offer remote management capabilities by implementing SNMP. This enables network engineers to remotely monitor network traffic and performance thereby helping to troubleshoot network ports. Intelligent hubs are also known as manageable hubs. Designing Planning. Ethernet Cabling Considerations. There are many restrictions on how Ethernet is cabled. To begin with there are these distance limitations 10Base2 Maximum of 185 meters. 10BaseT Maximum of 100 meters. 100BaseTX Maximum of 100 meters. 100BaseFX Maximum of 412 meters half duplex or 2000 meters full duplex . 1000BaseLX MMF Maximum of 316 meters half duplex or 550 meters full duplex . 1000BaseLX SMF Maximum of 316 meters half duplex or 5000 meters full duplex . 1000BaseSX Maximum of 316 meters half duplex or 550 meters full duplex . There are also limitations on the number of repeaters and cable segments allowed between any two stations on the network. There cannot be more than five repeated segments nor more than four repeaters between any two Ethernet stations. This limitation is commonly referred to as the 5-4-3 rule 5 segments 4 repeaters 3 populated segments . In Continued Introduction to Sniffer Pro Chapter 1 39 other words any possible path between two stations cannot pass through more than four repeaters or hubs nor more than three populated cable segments. It is important to note that there is also a maximum number of network devices that can be placed on an unrepeated cable segment. In 10Base2 there can only be 30 devices per unrepeated segment with a minimum distance of half a meter between T-connectors. In .