<P> The above rules describe one way of determining what spanning tree will be computed by the algorithm , but the rules as written require knowledge of the entire network . The bridges have to determine the root bridge and compute the port roles ( root , designated , or blocked ) with only the information that they have . To ensure that each bridge has enough information , the bridges use special data frames called Bridge Protocol Data Units ( BPDUs ) to exchange information about bridge IDs and root path costs . </P>
<P> The above rules describe one way of determining what spanning tree will be computed by the algorithm , but the rules as written require knowledge of the entire network . The bridges have to determine the root bridge and compute the port roles ( root , designated , or blocked ) with only the information that they have . To ensure that each bridge has enough information , the bridges use special data frames called Bridge Protocol Data Units ( BPDUs ) to exchange information about bridge IDs and root path costs . </P>
which are the port roles in stp protocol
which are the port roles in stp protocol
root designated blocked
root designated blocked