4.1　General Principles

4.1.1　Single module fiber shall be used in optical transmission network.

4.1.2　The configuration of the number of fibers in optical cables shall fully consider the network redundancy requirements，the future system type expected，the number of transmission systems，network reliability，development of new services，structure of optical cables，resource sharing of optical fibers and other factors.

4.1.3　Fiber in optical cables shall pass the full screening for tension that should be no less than 0.69GPa.Based on the applications，optical fibers should be selected according to the following principles：

1　Optical cables for long distance networks should adopt G.652 or G.655 optical fibers.

2　Optical cables for local networks should adopt G.652 optical fibers.

3　Optical fibers for access networks should adopt G.652 optical fibers whilst G.657 optical fibers should be adopted to meet special microbend need.

4.1.4　The capacity of cables shall be based on selection of appropriate cables，considering the distribution of users and user demand along with the nominal series of cables in order to fully leverage the pair utilization rate.

4.1.5　Multi-core cables shall be adopted for duct primary cables of cable line network in order to increase the number of pairs in one duct.