Communication Protocols – Lab 7

Rapid Spanning Tree Protocol and Ether-Channel

In this Lab, the students learn about how to optimize STP using Rapid Spanning Tree Protocol (RSTP) and ether-channel.

RSTP is IEEE 802.1W standard that is developed as an evolution of STP that provides faster spanning-tree convergence after topology change occurs. The basic STP takes about 30 seconds to be converged, while the RSTP need less than 1 second.

Ether-channel is Cisco proprietary protocol used to aggregate between 2 to 8 links in Cisco switches. The open standard version for ether-channel is IEEE 802.3ad. The main advantage to use ether-channel is the optimization use of bandwidth. By default, the STP will block any redundant links that create a loop on the network. Fortunately, using the ether-channel it is possible to aggregate the redundant links and treated them as one logical interface with the bandwidth equal to the sum of bandwidth of all aggregated links.