After analyzing the network layer and service characteristics of metro area transportation network

this article proposes a topology and statistic multiplex controlled manner which is appropriated for metro area network access layer.Moreover

this article proposes a solution to implement service protection on access layer with ring plus centenarian topology where centralized controlled statistic multiplex PON is adopted.With this solution and WDM

the PON is not only featured with the service protection

but also with the feature of larger capacity and lower cost

which could better satisfy the requirement of the service development of access layer of IP-oriented transportation network.