Manufacturer Usage Description (MUD) is proposed to enhance the security of IoT devices. However, MUD-enabled IoT networks are still prone to volumetric attacks because MUDs cannot perform rate-limiting. The existing solutions lack accurate detection of volumetric attacks in MUD-enabled IoT networks. This letter proposes MUDshield: a switch-native security framework to detect and mitigate volumetric attacks in MUD-enabled IoT networks. Initially, MUDshield calculates the flow features from incoming IoT traffic flows. Subsequently, it performs the in-network classification to detect attack traffic flows and perform appropriate action to mitigate the attack. The solution has achieved 99.97% classification accuracy with 7.32% CPU usage.