PVST/PVST+/RPVST/RPVST+

I wonder what is the difference between PVST/PVST+/RPVST/RPVST+

when I check spanning tree mode on the switch, I do not see the "+" sign
SW1(config)#spanning-tree mode ?
  mst         Multiple spanning tree mode
  pvst        Per-Vlan spanning tree mode
  rapid-pvst  Per-Vlan rapid spanning tree mode
Any clarifications will be helpful

Thank you
jskfanAsked:
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benhansonCommented:
MST is a more generic standard, but viewed as somewhat unwieldy by some.  PVST and RPVST are very similar but RPVST has faster convergence timing, meaning a spanning tree learn cycle can happen more quickly.  If you are in an all Cisco environment, use RPVST.  To the best of my knowledge, Cisco just does the + at this point(PVST+, RPVST+) and it pretty much denotes compatibility with IEEE standard PVST/RPVST/802.1w/802.1d.  So it says rapid-past but really means RPVST+, unless of course you are running a really ancient switch, (pre 12.1, or 2900XL/3500XL series)

Overall though, the biggest thing is to have all of your switches using the same flavor of spanning tree.
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Don JohnstonInstructorCommented:
Cisco hasn't supported true PVST in a long time.  It's all PVST+ or RPVST+ now.  So even though it doesn't show the "+", that's what it's running.
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jskfanAuthor Commented:
Thank you Guys !!
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