200 301 dumps pdf

200 301 dumps pdf.1.2 Basics 25Root switch optimal selectionFigure 2-1 Typical configuration choices: using the distribution switch as the root switchThe first part of this chapter introduced a variety of different topics that are more or less related in some way to STP configuration. It begins with some STP configuration options, which naturally relate the concepts of Chapter 1 to the configuration in this chapter. The next section describes some show commands to verify the default STP configuration before modifying it. This section also gives several examples of configuring core STP features and optional STP features.Setting STP ModeChapter 1 described how 802.1DSTP works in a VLAN. In this chapter, we turn our attention to STP configuration in Cisco switches, where the first question we encounter is: Which STP do you plan to use in your LAN? To answer this question, you need to have some background knowledge.The IEEE originally adopted IEEE 802ID as the standard for STP and first released it to the public in 1990. At that time, Cisco did not sell LAN switches and virtual LANs did not exist. the result was that the STP protocol went through several large changes as switches, VLANs, and other LAN technologies were introduced.Today, Cisco LAN switches allow the use of any of the three STP modes that reflect this history. For example, the mode discussed in this chapter, Per-VLAN Spanning Tree Plus (PVST+, or PVSTP), is a Cisco proprietary enhancement to 802.1DSTP. The Per-VLAN in the name indicates its main feature: PVST+ creates a different STP topology, the Per-VLAN, which is simply not possible with 802.1D. At the same time, fast ports were introduced in PVST+.As time passed, the IEEE improved on the 802.1D standard for STP with the RSTP (802.1w) protocol. Next, Cisco adopted the standard and made another improvement and took ownership of that improvement. This improvement created another mode in Cisco switches: Rapid PVST+, or RPVST+ for short. It has all the improved features of the latest IEEE standard, Per-VLAN.This book focuses on one of these modes: PVST+. Normally, Cisco switches use PVST+ by default, but to set the switch to use this mode, use the spannin-tree mode pvst global command. There is also a way to enable RPVST+ with the spanning-tree mode rapid-pvst command, and Multiple Spanning Tree (MST) with the spanning-tree mode mst command