[rbridge] A question about (R)STP and routing protocol

[Suping Zhai]

hi,
I am confronted with some questions when reading the Rbridge protocol related draft and hope someone can help me with details.
What's the essential difference between (R)STP and routing protocol(e.g. IS-IS)? 
How dose the routing protocol(e.g. IS-IS) can optimize the routing path while (R)STP can't? 
Can we optimize the (R)STP protocol itself to reach that goal? If that's the case, then I think that all RBridge WG works can be substituted. And I have seen some work been done in IEEE802.1aq which is on the way to the per bridge MSTP road. But what I imagine is that should we get a comparable simple and untangled solution for the bridge network routing path?

TIA.

Best Regards,
zhaisuping at huawei.com
Huawei Technologies Co., Ltd.
Tel: +86-10-82836882
Fax: +86-10-82836020
2006-02-23