> For the complete documentation index, see [llms.txt](https://mudassirs46.gitbook.io/network-fundamentals/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mudassirs46.gitbook.io/network-fundamentals/port-roles-in-rstp.md). # Port Roles in RSTP ### Port Roles in [RSTP](https://app.gitbook.com/@mudassirs46/s/network-fundamentals/~/drafts/-MRZ8l67L5MHnaQIEh9W/rstp-rapid-spanning-tree) | Port Role | Function | | ------------------- | ----------------------------------------------------------------------------------------------------------------------------------- | | **Root Port** | Same as STP's Root Port (Port with least Cost to reach the RB. Or else Least BID, Least Port Priority, Least Port Number) | | **Alternate Port** | Backup Root port if Root Port fails (same as Blocking Port (in discarding State)) | | **Designated Port** | Same as STP's Designated Port (Port with lowest Cost to reach the RB. Or else Lowest BID, Lowest Port Priority, Lowest Port Number) | | **Backup Port** | Backup Designated port if Designated Port fails (in discarding State) | | **Disabled Port** | Same as STP's Port (Administratively disabled) | | **Edge Port** | Ports connected to End devices (where STP is disabled generally) | #### Alternate Port: * Blocked ports are marked as Alternate Ports which are basically Backup Root Port. * If Root Port fails, this Alternate port becomes the RP immediately (generally in 1 sec) skipping the Listening & the Learning State. **Backup Port:** * The backup port role is only needed in the designs that are little unlikely today (E.g. A Switch connected to a HUB with 2 ports (in same Collision Domain) & HUB is connected to an End device). One from amongst these 2 ports will be Designated port and another port will be blocked marked as a backup port. ## Reference: * CCNA 200-301 OCG, Volume 1, Pg. 229-233 - Wendell Odom. * RST Notes *