1-11 MSTP ConfigurationWhen configuring MSTP, go to these sections for information you are interested in:z Overviewz Introduction to STPz Introduction to RSTPz Introduction to MSTPz Configuration Task Listz Configuring the Root Bridgez Configuring Leaf Nodesz Configuring the VLAN Ignore Featurez Configuring Digest Snoopingz Configuring No Agreement Checkz Configuring Protection Functionsz Displaying and Maintaining MSTPz MSTP Configuration ExampleOverviewAs a Layer 2 management protocol, the Spanning Tree Protocol (STP) eliminates Layer 2 loops byselectively blocking redundant links in a network, and in the mean time, allows for link redundancy.Like many other protocols, STP evolves as the network grows. The later versions of STP are RapidSpanning Tree Protocol (RSTP) and Multiple Spanning Tree Protocol (MSTP). This chapter describesthe characteristics of STP, RSTP, and MSTP and the relationship among them.Introduction to STPWhy STP?The Spanning Tree Protocol (STP) was developed based on the 802.1d standard of IEEE to eliminateloops at the data link layer in a local area network (LAN). Devices running this protocol detect loops inthe network by exchanging information with one another and eliminate loops by selectively blockingcertain ports to prune the loop structure into a loop-free tree structure. This avoids proliferation andinfinite cycling of packets that would occur in a loop network and prevents decreased performance ofnetwork devices caused by duplicate packets received.In the narrow sense, STP refers to IEEE 802.1d STP; in the broad sense, STP refers to the IEEE 802.1dSTP and various enhanced spanning tree protocols derived from that protocol.Protocol Packets of STPSTP uses bridge protocol data units (BPDUs), also known as configuration messages, as its protocolpackets.
