A loop avoidance mechanism called STP has been developed to alleviate the 3 issues above. There are two varieties of Spanning Tree Protcol, STP (802.1d) and RSTP ('Rapid' 802.1w) both work in a similar way. A Spanning Tree Algorithm examines the switched network, and, through a series of decisions (discussed below) places each port in the loop into either Forwarding or Blocking state, therefore breaking the loop. Types of port in STP: Designated Port (DP) Closest to Root i.e. All Ports on the Root Switch. Route Port (RP) One Per Switch. Blocking Port. The process the switches go through to decide which port they place in blocking or forwarding state is governed by the position of a 'Root Switch' (also known as 'Root Bridge'): To decide which switch is the root switch, each switch begins by claiming to be the Root Switch they all send out an STP messages called BPDU's (Bridge Protocol Data Unit). A fight-off happens to determine the fi...
Cisco Certified Network Associate Exam,640-802 CCNA All Answers ~100/100. Daily update