STP ports
STP ports
Hello everyone. I have a few questions regarding STP port states and data transmission through these ports. We're discussing two neighbor switches, S1 and S2, connected via a single cable in their f0/1 ports—each serving as the root port. The f0/5 ports are designated for specific functions. If S1 needs to send data to S2, but f0/5 of S1 lacks a connection to S2, how does the data transfer occur? I believe it's not happening through the root ports themselves, as they aren't meant for data exchange. They're just for establishing connections. Thank you for your attention!
You clarified your understanding of STP ports states. Based on your explanation, it seems each port in the STP configuration will eventually send data through the connected cable, whether it's a root or forwarding port. It’s similar to how data flows in a switch—first reaching the forwarding port, then the root port, and finally the next hop. That makes sense. An example with switches, ports, states, cabling would really help solidify this.
Review the STP phases and choose the root bridge accordingly. Once the setup is complete (45 seconds is the standard for STP), you can begin transmitting traffic. This is why enabling portfast on edge ports and using RSTP helps avoid the usual STP steps before data flow, preventing DHCP timeouts and allowing immediate forwarding. The path data delivery depends on the network layout, which can change based on incoming connections and whether L3 interfaces are present. In a triangle topology with Switch1, Switch2, and Switch3:
- Standard STP (802.1d) applies, no advanced features like 802.1w.
- Switch1 is designated as root due to priority settings.
- Switch2 and Switch3 become designated switches.
- Switch3 blocks one side while the other is a designated port.
If Switch1 fails, STP will reconfigure and switch states. This process may take 30 to 50 seconds for convergence, depending on STP timers and the topology.
They're attempting to mislead you, keep in mind the ports will match the slower speed; even though they're Gigabit ports, the connection remains fast Ethernet and charges the 19 cost.