The All-New Switch Book: The Complete Guide to LAN Switching Technology, Second Edition

5.3. Rapid Spanning Tree Protocol

The Rapid Spanning Tree Protocol (RSTP) is a transformation of the Spanning Tree Protocol and is the one that is being implemented in most LANs today. Both standards are compatible with one another within a catenet; however, the improved performance intended by the RSTP may not apply in these mixed catenets.

Not only is RSTP backward compatible with Legacy bridges that are using STP, but the nice thing about RSTP is that it is also easy to configure. Most of the parameters are the same, which makes it easy from a Network Design perspective.

RSTP is amendment IEEE 802.1w to the 802.1D standard.

5.3.1. RSTP State of the Port Address

We are happy to report that the state of the ports has changed in RSTP. (Thought we would start off this section in a professional and friendly manner.) Take a look back at Figure 5-2. No longer do we concern ourselves with the five port states in STP: Forwarding, Learning, Listening, Blocking, or Disabled. The ports states Blocking, Disabled, and Listening have been merged to a single port state: Discarding. Table 5-3 compares them.

Table 5.3. RSTP Port State Behavior

RSTP (802.1D) IN PORT STATE	STP (802.1D) EQUIVALENT	LEARN MAC ADDRESSES	INCLUDE PORT ACTIVE TOPOLOGY
Discarding	Disabled	No	No
Discarding	Blocking	No	No
Discarding	Listening	No	Yes
Learning	Learning	Yes	Yes
Forwarding	Forwarding	Yes	Yes

It is safe to say that the state of any ...