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New Member

stp vs rstp

Hi all , Is the main difference here just that rstp uses a backup/alternate port ? and what is the diff between alternate and backup port ?

Cisco Employee

Re: stp vs rstp


There are some more differences between the STP and RSTP.RSTP has only 3 states where as STP has five states.RSTP Convergence time is very less as compared to STP. Please go through the link below for more understanding on the diffrence and various ports:


-amit singh

Re: stp vs rstp

Hello carl,

see if the below terminologies help you :

Alternate port:

The alternative port is a switch port that offers an alternative path toward the root bridge. the alternative port assumes a discarding state in a stable, active topology. an alternative port is present on nondesignated switches and makes a transition to a designated port if the current designated path fails.

backup port

the backup port is an additional switch port on the designated switch with a redundant link to the segment for which the switch is designated. A backup port has a higher port ID than the designated port on the designated switch. the backup port assumes the discarding state in a stable, active topology.

Got this from a web page in CCO !!!


New Member

Re: stp vs rstp

RSTP is design to improve the convergence.

Like its waits for three missed Hell instead of 10

it transtion from disable state to learning bypassing listening stage

Its provide Back DP.

RSTP uses following three link type

Shared: connected to hub

edge : connected to computer

point-to-point connected to switch.


New Member

Re: stp vs rstp

Alternate Port is like Cisco Uplink fast keep track the alternate port to the root if root port goes down.

Backup port role is to provide backup to Designated port, if a switch is connected to a segment with more than one port.