Will URL changes cause rankings to drop?

[Whitey]

I'm a bit worried.

We are converting a site from Perl to .asp and realise that we have messed up some of our originating URL's by not having consistancy.

Levels 1 thru 4 are fine. They all end in "/" so conversion via rewrite techniques are fine. But at level 5 we are going to halve the no. of URL's [ which will eventually improve the overall site's strength ], however, here's the BIG worry :

Level 5 URL's end in .htm . I don't think we can replicate this extention in .asp. Can we?

So if we 301 them from .htm to "/" [ or .asp which i suppose we wouldn't do ] how can we avoid a ranking drop, since all Level 5 URL's will need to be reindexed and re -ranked. Has anyone managed this successfully without loosing rankings?

[tedster]

You can instruct the IIS server to send .htm files to the .NET ASP parser - then you don't need to change urls, which as you know, will most likely cause troubles for a while.

As for the technical details, there are MANY such discussions in our Microsoft IIS forum [webmasterworld.com] - do a site search and you'll have quite a reading assignment. Here's one thread that popped up for me with some instructions:

Parsing .html pages as .asp [webmasterworld.com]