Contents
How much does it cost to change STP ports?
By changing the STP port costs with the command spanning tree [vlan vlan-id] cost cost, you can modify the STP forwarding path. You can lower a path that is currently an alternate port while making it designated, or you can raise the cost on a port that is designated to turn it into a blocking port.
What are the rules for STP configuration on switches?
After the root switch identification, the switches adhere to these rules:
- STP Rule 1—All ports of the root switch must be in forwarding mode.
- STP Rule 2—The root port must be set to forwarding mode.
What happens if two switches have the same priority?
If two or more switches have the same priority, the switch with the lowest MAC address becomes the root bridge. The reason the bridge priority value in Figure 3-8 displays 32,769 instead of the default value 32,768 is that the STA also adds the default VLAN number (VLAN 1) to the priority value.
What is STP in switch?
Spanning Tree Protocol (STP) is a Layer 2 network protocol used to prevent looping within a network topology. STP was created to avoid the problems that arise when computers exchange data on a local area network (LAN) that contains redundant paths.
What is STP path cost?
The path cost is the metric STP uses to calculate the shortest path to the elected root bridge. The path cost is based on the speed of the bridge port interface. You can confirm the path cost method being used on your Cisco switch with “show spanning-tree summary” command.
What are STP costs?
Path cost – The path cost is the metric stp uses to calculate the shortest path to elect root port to reach the root-bridge . The path cost is based on the speed of the interface of switch .
What kind of switching protocol does STP use?
STP is a Layer 2 switching protocol used by classic Ethernet [1], which ensures loop-free network topologies by always creating a single path tree structure through the network.
Why are core switches required for spanning tree?
A second cost factor is derived from the critical nature of core switches on which the entire “tree” depends. The tree network architecture means that customers are expending large amounts of money for zero business value. Core switches are required to support the access switches that connect servers, which generate business value.
Why is spanning tree more complex than STP?
Configuration and implementation of MLAG on a day-to-day basis is more complex than STP itself (note issues like peer detection, orphan ports, and MLAG primary/secondary). Scalability is poor; typically only two switches can be bonded, though eight is possible with a number of limitations. Code dependencies prevent migration and updates.
Is the Cisco Catalyst 5500 compatible with STP?
Although this document uses Cisco Catalyst 5500/5000 Switches, the spanning tree principles that the document presents are applicable to almost all devices that support STP. For the examples, this document used: