While LFS is capable of mounting network file systems such as NFS, these are not mounted by the mountfs init script. The tools needed to mount these systems may not be available on the root partition and the network file systems need to be mounted after the networking is activated. These file systems also need to be unmounted before the network goes down.
Install the /etc/rc.d/init.d/netfs network mount script included with the blfs-bootscripts-5.1 package.
make install-netfs