Why I can connect WAN Interface between Node A as I used 10GE SFP LR and Node B as I used 10GE SFP ER . distance between Node A to B is 8 KM
If it was my network, I would change it so they had the same transceiver type. My reasoning is that it makes for an easier network to troubleshoot in the future; especially if I needed to speak with Cisco TAC.
The optical receive levels are comfortably within each modules specifications, so the network should be stable and run clean as is.
My only concern on the actual power levels you provided would be at the receive end at Node B. I would have expected a fiber link loss in the 2 to 3dB range (8km @ .25dB loss/km + connector/splice loss); instead, this link is showing 10dB loss (+1dB TX power @ Node A minus -9dB @ Node B). Could be the fiber link has connectors (instead of splices) in the outside plant; or has dirty connectors or an fiber bend. Were these losses measured with an optical test set or through querying the SFPs?
Hope this helps!
Using 10GE LR on one end and 10GE ER on the other should work as long as the optical receive levels on each end fall within the specs of the SFP module. Most optical receivers used in SFPs are wideband: meaning they are able to receive a wavelength in either the 1310 and 1550nm windows. Although this is the case, many manufacturers will not gaurantee the performance of the link with mixed modules; mainly due to the additional test cases required to qualify the performance across many SFP suppliers. Also, it can make future link troubleshooting more confusing to the technicians.
I would recommend checking the optical receive levels on both links to see where it falls in the SFP's receiver window: to make sure the power level is not at the edge of the receiver's operating window.
Hope this helps!