Optional STP Features

The first major section of this chapter defines STP has standardized in IEEE standard 802.1D. STP as described in that first section has been around for about 30 years. Cisco switches today still support and use STP. And other than changes to the default cost values, the description of STP in this chapter so far works like the original STP as created all those years ago.

Even with such an amazingly long life, STP has gone through several changes over these decades, some small, some large. For instance, Cisco added proprietary features to make improvements to STP. In some cases, the IEEE added these same improvements, or something like them, to later IEEE standards, whether as a revision of the 802.1D standard or as an additional ...

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