At this time, packet filtering as a tool isn't as popular and well developed for non-IP protocols, presumably because these protocols are rarely used to communicate outside a single organization over the Internet. (The Internet is, by definition, a network of IP networks.) If you are putting a firewall between parts of your network, you may find that you need to pass non-IP protocols.

In this situation, you should be careful to evaluate what level of security you are actually getting from the filtering. Many packages that claim to support packet filtering on non-IP protocols simply mean that they can recognize non-IP packets as legal packets and allow them through, with minimal logging. For reasonable support of non-IP protocols, you should look for a package developed by people with expertise in the protocol, and you should make sure that it provides features appropriate to the protocol you're trying to filter. Products that were designed as IP routers but claim to support five or six other protocols are probably just trying to meet purchasing requirements, not to actually meet operational requirements well.