The active LED indicates the following:

∙Orange—The Supervisor Engine is in standby.

∙Green—The Supervisor Engine is operating correctly.

Other LEDs are on the individual line modules, as shown in Figure 16.2. These LEDs indicate the status of each module. A green link light indicates a good established link. An orange or amber link light indicates a problem with the link. A red light indicates that a non−port test has failed.

Figure 16.2: The 10/100 Ethernet module LEDs.

Note A green switch port (SP) light indicates that the port is operating at 100BaseT. When the SP light is off, the port is operating in 10BaseT.

Switch Cabling

The amount of data traffic that can float down a single pipe is almost unimaginable. With the introduction of 1− and 10Gbps links as well as Fast and Gigabit EtherChannel, data can move around today’s networks at lightning speed. When gigabyte hard drives were first introduced for Intelligent Drive Electronics (IDE) drives, to copy one gigabyte to another drive took hours—even days. Now, you can send whole gigabytes over a network in mere seconds.

This higher speed adds complexity like never before. In early implementations, cable distances had greater flexibility. In today’s high−speed networks, the distance limitations should be strictly adhered to. Many times, administrators will upgrade the network interface cards on both ends of a former 10Mbps link and find that the new 100Mbps link fails to work or has an excessive number of errors, forcing the link to become unusable. This happens because exceeding the 10BaseT cable limits didn’t have the same detrimental effect as exceeding limits on 100BaseT.

You also may have a non−compatible cable type. For instance, 10BaseT will work over Category 3 twisted−pair, whereas 100BaseT requires Category 5. Table 16.2 shows the common cable limits for cabling in today’s networks.

Table 16.2: Cable distance limitations.

It’s hard to use a network sniffer on a switch the way you can in a flat topology network, because the switch isolates traffic, segments broadcast domains, and makes each port the collision domain. This isolation forces an administrator to manually connect a network sniffer to each port on a switch to monitor the traffic.

311