How STP Works 45
How RSTP Differs to
STP
RSTP works in a similar way to STP, but it includes additional information
in the BPDUs. This information allows each bridge to confirm that it has
taken action to prevent loops from forming when it wants to enable a
link to a neighbouring bridge. This allows adjacent bridges connected via
point-to-point links to enable a link without having to wait to ensure all
other bridges in the network have had time to react to the change.
So the main benefit of RSTP is that the configuration decision is made
locally rather than network-wide which is why RSTP can carry out
automatic configuration and restore a link faster than STP.
STP Example Figure 10
shows a LAN that has STP enabled. The LAN has three
segments, and each segment is connected using two possible links.
Figure 10 Port costs in a network
■ Bridge A has the lowest Bridge Identifier in the network, and has
therefore been selected as the Root Bridge.
dua1730-0bAA03.book Page 45 Monday, July 11, 2005 11:14 AM
To Next Page
Loading...
