This paper deals with bandwidth management of the upstream channel of a CATV network. The upstream channel bandwidth must be splitted between random access and reserved access. This splitting is obtained via a framing protocol. This framing may be «explicit» i.e. defined by special control signals or «implicit» i.e. defined by the reservation scheme. We describe in details four framing management schemes of the upstream channel. We then study these framing management schemes with simple analytical models.An asymptotic average access delay analysis (when the propagation is large) is provided. As a result of our models, we show that implicit framing outperforms explicit framing schemes.