Hi Ammavan,
The following URLs are good for MSTP and RSTP.
MSTP: http://www.cisco.com/warp/customer/473/146.html
RSTP: http://www.cisco.com/warp/customer/473/147.html
RSTP is an evolution of 802.1d spanning tree protocol. The logical topology that the network converges to with RSTP/MSTP is the same as what the network would converge to with 802.1d. However, there are several changes in the RSTP protocol including a new BPDU format, port role changes, how switches handle the BPDUs etc. The above link gives more details on each of these changes.
RSTP builds just one logical topology for all vlans. However with the Cisco implementation, similar to PVST+, RSTP is implemented as R-PVST+. What this means is that we will run a separate RSTP instance for each vlan. Hence we can load balance in this way.
MSTP is built on top of RSTP. One key difference is that MSTP allows you to group a set of vlans into a particular instance. Hence if you have a thousand vlans, you can group half of the vlan into instance 1 and the other half in instance 2. Hence there will be two instances of spanning tree running in the network then.
Hope this is not too confusing. Please read the above links and if you have any questions, please write in and I will try and explain more in detail.
regards
-Alok
