Hi Ankur,

I would like to know, what should I concern about when configuring MSTP Mode?? it gets me confused alittle bit!!! Have u implemented it before?? And is there any restriction that i should concern about? My last point, if numbers of vlans pointed to a single MST is unlimited, then there is no point of using 65 MST cause I can map all my vlans supported on the switch to a single MST!!!

Does the above make sense or not??

Let me know your Thoughts.

I thank u ankur in advance,

Hi Friend,

I have never implemented MSTP so cannot give u deep insight about the same.

Yes you can have all vlans in same MSTP instance but then it will bahave like a CST which is common spanning tree instance for all vlans for me which will bring all the disadvantages which you get in CST.

Let Bobby or come Cisco TAC engineer answer this in detail.

Regards,

Ankur

Hi there,

As Ankur replied, using MST (MIST) brings the concept of CST into the design.. One of the differences which makes MIST better is the ability to have several instances (65 as stated).

The problem with a CST is that all of your VLAN's must behave similar.. that is, you can't block just one and one VLAN off a trunk if you expect to have redundancy intact. In MIST you can consider each instance a separate CST, so you'll have to design your LAN with a maximum of 65 different spreadout's.. This should be enough for your needs...

You should read this document thoroughly *before* you attempt using MISTP:

http://www.cisco.com/en/US/tech/tk389/tk621/technologies_white_paper09186a0080094cfc.shtml

Did it help? If so, please rate it.

Hi guys,

I thank u both for your inputs, it's so helpfull, I just have one last question, what is a CST??

Thank you,

HI

CST means common spanning tree.it is ieee implementation.in CST u have a single instance of STP for all u r VLANS unlike PVST which has a seprate instance for evry VLAN.

Thanks

Mahmood

Hi Mahmood,

Thanks for ur input, its quite helpful.