c3845 with NM-1A-OC3-POM needs a 10db attenuator to work with Nortel Passport Card 2pOC3SmAtm2

We had a cisco 3845 router for which we ordered NM-1A-OC3-POM for our connectivity with Nortel Passport.

Our Nortel Passport interfaces with service providers MUX to provide L2 connectivity over ATM/FR.

Now we realised that the Nortel Passport card was a LR (Long Reach one) whereas the SFP for c3845 (POM) that we ordered was a IR (Intermediate Reach).

Thus either we had to replace the card on the passport or the SFP on the C3845.
Both were difficult to do. Considering not readily available in India and the high price.

Luckily when we approached Cisco TAC and provided them details with Nortel passport's Power Details, the TAC confirmed that the Passport was transmitting too high a power for c3845 IR SFP to handle and hence was loading it.

Thus Cisco TAC recommended we use a 10db attenuator to circumvent the power problem.
Once we did that, our Links came UP.

Thus next time you try doing inter vendor operability, pls ensure that:-
1) You consult the vendors before placing the orders.
2) Review the Technical Specifications

unfortunately we didn't do the above and had to suffer at least 1 month of delay to get the circuits up.

I paste below the Snippet of the various outputs from the c3845

Cisco IOS Software, 3800 Software (C3845-ENTSERVICESK9-M), Version 12.4(5a), RELEASE SOFTWARE (fc3)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2006 by Cisco Systems, Inc.
Compiled Sat 14-Jan-06 02:38 by alnguyen


ATM OC3-POM (SMIR) Port adapter, 1 port
Product (FRU) Number : NM-1A-OC3-POM

interface ATM2/0
description : Connect to Nortel Passport
no ip address
no ip redirects
no ip proxy-arp
atm sonet stm-1
no atm ilmi-keepalive
end

Nortel Passport Chassis:-
nortel passport 7480

Nortel Passport Card Used:-
Card type:- 2pOC3SmAtm2 and productCode NTNQ66AA-21