the in-band interface does not get an IP. The DHCP reply packets have been traced and it is seen that they reach the NNI port but do not reach the host CPU interface and hence the host in-band CPU interface does not get an IP.
The DHCP Request packets do traverse from in-band host CPU interface to NNI port successfully in the upstream. The issue seems to be only in the downstream.
When this issue happens, if the OLT is rebooted things start working fine again.
Currently we are working with a workaround to reboot the OLT if the in-band interface does not get an IP within a configured timeout value.