To my understanding, there are some limitations to mixing SONET line cards with DWDM line cards in the same ONS 15454 chassis. I believe one of the limitations had to do with the line card placement versus a OSC-M and OSC. I can't remember the draw backs of doing the above, but there was some negative.
Are there any more draw backs, limitaitons or gotchas?
Also, generally, the optical engineers I spoke to recommended never mixing the cards and keeping them in seperate chassis.
Typically you don't mix them. In MSTP there are no XC cards, so that takes care of MSPP cards in MSTP. Transponders can go in any shelf, since the shelf is just a way to talk and control the card; I believe amps and pre-amps will work (in MSPP), but you must then control the output modes by hand, and that can be tricky.
Putting MSTP into a MSPP can be done, but again, if you need OSC cards, they go where XC's are located, unless you use OSC-CSM's and that starts up a whole host of new real estate problems. So those are some of the issues you might think about.
If u can fit all ur SONET and DWDM line & common cards in same chasis and will not be upgrading for years, then its fine.
Simple drawback of mixing cards will be that ur system will not have slots, when u want to upgrade. So if u have to use 2 chasis then why not make ur life easier by using 1 for SONET and 1 for DWDM cards.
Mixing SONET/SDH and DWDM functions in the same chassis is a supported configuration on the ONS 15454 platform.
As was stated in the other posts, you would have to install the SONET/SDH crossconnect cards in the chassis in order to have the HO/LO functionality.
You are right, that there is an impact on the card placement in the chassis, however you can force the planning tool (Cisco TransportPlanner) to leave the required slots for the XC cards empty when designing the DWDM network.
The model described so far is what is commonly referred to as a "hybrid" node.