- Radius does not support transmission level security and hence in roaming case it is more susceptible to attacks .
- For roaming, intermediate proxy server is required for chaining purpose, Radius does not provide explicit support for proxies.
- Radius does not provide data object security mechanism, hence if any untrusted proxies has altered message attributes, then radius is not able to detect it.
Because of these problems, Radius cannot be used for roaming. All these problems can be overcame by Diameter protocol, hence diameter is used.
