Difference Between Similar Terms and Objects

Difference Between STP and RSTP


In a computer network, the interconnection of the computers results in having more than one possible path to reach a given destination. In order to choose the best path for the packets to travel across and to prevent looping, STP or the Spanning Tree Protocol was created. STP was created in 1985 and is a very old protocol. In 2001, a new protocol named RSTP or Rapid Spanning Tree Protocol was created as a successor to STP. RSTP is far superior to STP and should be used in any network.

The addition of the word rapid should already be a hint on how RSTP improves on STP. In STP, if the topology changes either because of a new link added or a link lost, it can take anywhere between 30 to 50 seconds in order to adapt to the new topology and provide the least cost path. With RSTP, that is reduced to three hello times, which has a default value of 2 seconds for a total of 6 seconds. The ability to adapt new topologies is very advantageous especially when dealing with high volume traffic in order to avoid lost packets.

BPDUs (Bridge Packet Data Units) are used to exchange information about network topology. RSTP is able to respond to BPDUs from the direction of the root while STP cannot. This enables an RSTP bridge to provide spanning tree information to its ports. If the receiving bridge recognizes that the information it receives is superior, it will then send an agreement to the sending bridge. Because the receiving bridge already has the information, it can then bypass the typical learning/listening states of STP and directly go to the forwarding state; thereby allowing the receiving bridge to function properly much faster than in STP.

As a replacement to STP, RSTP maintains backwards compatibility so that the transition from one to the other doesn’t necessarily have to mean replacing all your hardware at once. The downside to this is that the benefits of RSTP do not appear as long as you have old STP equipment connected. RSTP equipped devices are programmed to automatically revert to STP operation if a STP only device is connected to the network.


RSTP is the successor to STP
RSTP responds much faster than STP
RSTP responds to BPDUs in both directions while STP does not
RSTP is backwards compatible with STP

Sharing is caring!

Search DifferenceBetween.net :

Email This Post Email This Post : If you like this article or our site. Please spread the word. Share it with your friends/family.

1 Comment

  1. STP vs RSTP

    in stable topology of stp only root bridge generates BPDUs where as in rstp all bridges generates BPDUs for every 2 secs(used as keep-alive msgs).

    port state in stp:

    1. Disable
    2. Blocking
    3. Listening
    4. Learning
    5. Forwarding

    port states of rstp:

    1. Discarding
    2. Learning
    3. Forwarding

    port roles of stp :

    1. Root port
    2. Designated port
    3. Nondesignated port

    rstp port role:

    1. Root port
    2. Designated port
    3. Alternate port
    4. Backup port

    stp convergence time:
    30 secs – direct link
    50 secs – indirect link

    rstp convergence :
    <=6secs by default i.e., 3*hello interval time

    flag bits used by stp:

    bit 0: TCN
    bit 7: TCA

    flag bits used in rstp:

    0: TCN
    1: proposal
    2,3: port role
    4: learning
    5: forwarding
    6: agreement
    7: TCN

Leave a Response

Please note: comment moderation is enabled and may delay your comment. There is no need to resubmit your comment.

Articles on DifferenceBetween.net are general information, and are not intended to substitute for professional advice. The information is "AS IS", "WITH ALL FAULTS". User assumes all risk of use, damage, or injury. You agree that we have no liability for any damages.

See more about : , ,
Protected by Copyscape Plagiarism Finder