Question

Use the following questions to guide your discussion:

What represents an effective troubleshooting routine for switches?

What elements of switch operation need to be checked to implement troubleshooting?

What tools can assist with switch troubleshooting?

Answer 1

Answer :

There are many ways to troubleshoot a switch. As the features of switches grow, the possible things that can break also increase. If you develop an approach or test plan for troubleshooting, you are better off in the long run than if you just try a hit-and-miss approach. Here are some general suggestions to make your troubleshooting more effective:

• For the more complex situations, have an accurate physical and logical map of your network. A physical map shows how the devices and cables are connected. A logical map shows what segments (VLANs) exist in your network and which routers provide routing services to these segments. A spanning tree map is highly useful to troubleshoot complex issues. Because of the ability of a switch to create different segments with the implementation of VLANs, the physical connections alone do not tell the whole story; one has to know how the switches are configured to determine which segments (VLANs) exist and to know how they are logically connected.

• Have a plan. Some problems and solutions are obvious; some are not. The symptoms that you see in your network can be the result of problems in another area or layer. Before you jump to conclusions, try to verify in a structured way what works and what does not. Since networks can be complex, it is helpful to isolate possible problem domains. One way to do this is to use the OSI seven-layer model. For example: check the physical connections involved (layer 1); check connectivity issues within the VLAN (layer 2), and check connectivity issues across different VLANs (layer 3), etc. If there is a correct configuration on the switch, many of the problems you encounter are related to physical layer issues (physical ports and cabling). Today, switches are involved in layer-three and four issues, which incorporate intelligence to switch packets based on information derived from routers, or actually have routers that live inside the switch (layer-three or layer-four switching).

• Do not assume a component works without checking it first. This can save you a lot of wasted time. For example, if a PC is not able to log in to a server across your network, there are many things that can be wrong. Do not skip the basic things and assume that something works; someone can have changed something and not told you. It only takes a minute to check some of the basic things (for example, that the ports involved are connected to the right place and are active), which could save you many wasted hours.

What elements of switch operation need to be checked to implement troubleshooting:

PORT Functions:

If the port does not work, nothing works! Ports are the foundation of your switching network. Some ports have special significance because of their location in the network and the amount of traffic they carry. These ports include connections to other switches, routers, and servers. These ports can be more complicated to troubleshoot because they often take advantage of special features like trunking . The rest of the ports are significant, as well, because they connect the actual users of the network.

Hardware Issue : it might be possible that there is some kind of hardware issues which is causing some kind of connectivity problems.

tools can assist with switch troubleshooting?

Using Router Diagnostic Commands

routers provide numerous integrated commands to assist you in monitoring and troubleshooting your internetwork. The following sections describe the basic use of these commands:

•The show commands help monitor installation behavior and normal network behavior, as well as isolate problem areas.

•The debug commands assist in the isolation of protocol and configuration problems.

•The ping commands help determine connectivity between devices on your network.

•The trace commands provide a method of determining the route by which packets reach their destination from one device to another.

What tools can assist with switch troubleshooting?