CCNA RnS Article #33: How STP & RSTP Relate?

CCNA RnS Article #33: STP & RSTP Relation

In this article, we are going to cover how STP & RSTP relate. From time to time evolution happens in technology and new features are developed to take full advantage of the technology. 

CCNA RnS Article #33: How STP & RSTP Relate?
Fig 1.1- Spanning Tree topology

The same rule suits well for STP with the introduction of the Rapid Spanning Tree Protocol.

Related: All about RSTP- Rapid Spanning Tree Protocol with Configuration

802.1w (RSTP) standard was amended to 802.1d in 2001 this was the first standardized RSTP. After some time, new features were added to the standards as well, and IEEE replaced STP with RSTP in the revised 802.1D standard in 2004. Finally, in 2011, IEEE moved all RSTP standard information to the revised 802.1Q standard. So, if you want to read the RSTP standard, you need to refer IEEE 802.1Q standard document which is for Trunking.

To start with let’s try to understand what is common in STP and RSTP. This is required, as RSTP is based on STP and an understanding of STP is an added advantage. If you want to read about STP, please refer to earlier articles on STP.

Both RSTP and STP elect the root switch and the selection is based on the same rules as covered in the STP article

Both RSTP and STP select root ports to forward traffic or to reach to root switch. Root port election too follows the same rule of STP.

Both RSTP and STP select the designated ports on each LAN segment with the same rules

With these similarities, it is possible for RSTP & STP to work on the same network without any problem. I mean switches that support STP ruse STP and RSTP can run RSTP without any complaint. If that is so friendly between them then what is needed to develop RSTP? The answer is an improvement in convergence time from 50 seconds to a minimum of 6 seconds.  

Now we understand what the relationship between STP & RSTP is, we’ll be looking at the various RSTP concepts in the next article. I hope you find this informative.

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