Ongoing maintenance is a fact of life.
NOTE Spanning Tree Protocol is covered in further detail in Interconnecting Cisco
Networking Devices Part 2 (ICND2).
192 Chapter 2: Ethernet LANs
Using a Layered Approach
Switches operate at multiple layers of the Open Systems Interconnection (OSI) model. At
Layer 1 of the OSI model, switches provide an interface to the physical media. At Layer 2
of the OSI model, they provide switching of frames based on MAC addresses. Therefore,
switch problems generally are seen as Layer 1 and Layer 2 issues. Some Layer 3 issues
could also result, regarding IP connectivity to the switch for management purposes. The
following sections describe using a layered approach to identify common switched network
issues.
Identifying and Resolving Media Issues
Media issues are common. It is a fact of life that wiring gets damaged. These are some
examples of everyday situations that can cause media issues:
?– In an environment using Category 3 wiring, maintenance installs a new air
conditioning system that introduces new electromagnetic interference (EMI) sources
into the environment.
?– In an environment using Category 5 wiring, cabling is run too close to an elevator
motor.
?– Poor cable management puts a strain on RJ-45 connectors, causing one or more wires
to break.
Pages:
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284