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New Member

RSTP Port States

Hi,

Can anybody clarify the port states in RSTP.

Discarding, Learning & Forwarding.

Does the port state move to 'Blocking' after it finds a redundant link or 'Discarding'

Regards,

Pratik

3 REPLIES

Re: RSTP Port States

Hello Pratik,

a good review of port roles can be found f.e. at

http://www.cisco.com/en/US/products/hw/switches/ps628/products_configuration_guide_chapter09186a00800d84bc.html#1034652

and a description of the "Sequence of Events During Rapid Convergence", which includes what port state can follow which other port state can be found at

http://www.cisco.com/en/US/products/hw/switches/ps628/products_configuration_guide_chapter09186a00800d84bc.html#10743

Hope this helps! Please rate all posts.

Regards, Martin

New Member

Re: RSTP Port States

Hi Martin,

Thanks for replying. I have both the documents you have mentioned. My query is that what is the state called after ports are synced & redundant link has been found. Is it a discarding port or still called blocking port in RSTP (PVRST)

Thanks,

Pratik

Re: RSTP Port States

That's a terminology issue. Up to 802.1D-1998, STP used to only have some port state: listening, learning, forwarding or blocking. As of RSTP, the protocol now includes not only states (learning, forwarding and discarding) and roles (designated, root, alternate, backup (and master for MST)).

Basically, the state have been simplified: listening and blocking are now just "discarding". These three mean exactly the same from an operational point of view. It's just that we kept the old naming in our implementation. So you can still see the difference between listening and blocking, which is of little use in fact;-)

Regards,

Francois

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