RCP Monitoring for Exchange 2010

I am trying to get my head around the best way to monitor the RPC service on an Exchange 2010 CAS.

I am running 10.2.2 and originally followed the Exchange 2010 deployment guide (http://www.f5.com/pdf/deployment-gu...010-dg.pdf) to deploy RPC/MAPI services -- this creates a TCP type monitor with TCP 135 as an Alias Service Port.

When we tried disabling RPC services on the CAS, port 135 would still be listening and therefore marked the pool members up so that's no good.

We later discovered that disabling the RPC service on the CAS only really shuts port TCP 443 down while port TCP 135 is still left listening.

The way I see it I have 2 options:

1) create a TCP monitor on port 443

2) create an HTTPS monitor and send RPC calls over HTTPS

And here lies the issue, neither of those options seems ideal - if IIS goes down I don't want the RPC pool members to be marked down just because IIS has gone down.

Has anyone come across a better way of monitor JUST the Exchange RPC service, perhaps via an external monitor?

Thanks,

Claud