With the telcom example I've provided above there is no generic OS used for that - the protocol (e.g. TCP, IP or even HTTP) is (pre-)processed within the hardware and not further up in the OS.
Generally Linux / Unix (carrier grade / HA) is used within such environments as the OS. Context switches (user land / kernel) are some of the most expensive operations so they are to be avoided as often as possible.
What you're pointing to are features you generally find in RTOS (real-time OS) solutions - and these kind of cards / platforms allow using them. Look up the Trillium platform from CCPU for example how such a stack / system is layered - they use Wind River PNE-LE (Linux edition for network equipment) for the HA & non-HA protocols.
