Hi,

1.What is the use of MST?

          MST is used when you want to have separate instances of STP for different Vlans or set of Vlans.

                    e.g.      MST 0 = Vlan 1,2,3,4

                                MST 1 = Vlan 5,6,7

They maintain different set of blocked and forwarding ports per MST instance, so if one trunk port may be blocked for MST 0 while it could be forwarding for MST 1.

2.Difference B/W MST and CST and RSTP?

          CST is one STP domain for all Vlans ( so called as Common Spanning Tree protocol)

3.Other than Convergence, is there any advantage for RSTP over STP?

          You have luxury of using Uplinkfast and Backbone fast with RSTP

4.Which protocol  i have to prefer if other end will be D-Link Switch?

     RSTP, PVST, RPVST+, MST all are backward compatible with STP.

so if you run STP on Dlink and RPVST on Cisco switch, its backward compatible but the Dlink will block port for every Vlan and will have single STP domain while Cisco can have different STP domain as configured

HTH

Hitesh Vinzoda

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