I'm looking to use two PTP650/670 links through a common repeater site. These links will be running TDM traffic. However, no traffic needs to be dropped at the repeater site. Do I need any NIDU's at the repeater site, or can I just bridge the traffic between the the ODU's with an Ethernet cable? If I do need NIDU's at the repeater site, do I need two or can I do it with one? Again, no traffic is going to be dropped at the repeater site.
NIDU-->PIDU-->ODU 1 site A --------> ODU 2 repeater site ???? ODU 3 repeater site ---------> ODU 4 site B-->PIDU-->NIDU
You will need two NIDUs at the intermediate repeater site, interconnected using E1/T1 cables, so that part of the network will look like:
The reason for this, and many other frequently-asked questions are answered here: ptp-nidu-faq
The NIDU is a simple and effective solution to the basic task of delivering E1/T1 with low latency and very low wander over a TDD wireless link. It's not a general purpose TDM multiplexer, and can't be used to span more than one wireless link.