Christoph sent me an interesting question a few days ago:
I played a bit arround with 2 Cisco 1803 and I found MPLS related configurations commands in IOS 12.4(15)T (Advanced Enterprise) on this box. MPLS was not listed as a included fearture in the Cisco Feature Navigator for this image and some searching at cisco.com took me to a 2 year old document telling me that MPLS isn't supported on this series. Some more searching took me back to the Cisco Feature Navigator which lists MPLS as feature for the Cisco 1805 router (which uses the same IOS image, afaik).
So, I'm a bit confused now if MPLS is really working / supported on the low-end Cisco ISR 1800 fixed series?
MPLS was mostly available but never supported on low-end platforms (including Cisco 2600). In those days I've taken some heat for reusing existing 2600-based labs to teach Cisco-internal MPLS courses (since we were teaching the students to configure unsupported devices :).
Anyhow, the "not supported" means exactly that: it may be available (well, it is), it may work (it actually does), but if it's broken (and I've seen at least one low-end-platform-specific bug in the early days) you can't complain.
Is anyone aware whether the official support for the MPLS on 1800 series has changed? If so, please share your information with us.
If you need to offer a production-grade service to your customers, don't use unsupported equipment; if you need a solution for your personal needs or you're building a lab, go ahead.