A few basic questions on network connectivity for ATM machines to a bank network.
All ATM machines are connected to the main bank branch through MPLS. Now, they want a backup link through ISDN.
I am proposing a 3845 with an ISDN network module on main branch end and 1841 with ISDN BRI S/T-V3 on ATM end.
The following are my questions:
1. If there are 10 ATM MPLS links, do i need 10 ATM backup IDSN connections? Or do i need just 5 ATM ISDN connections (if i use just one BRI channel per MPLS link)?
2. On the main branch end, i need to know how practical is it to have 1 ISDN backup link for every ATM connected to it?
I believe that 2 ISDN backup links should be practically sufficient for 5 MPLS primary links. There are very less chances that all 5 MPLS links go down at the same time. Right? So even 2 ATM backups should be fine in my opinion. But if i am wrong in my understanding, please let me know?
3. If we go for 1 ISDN BRI Network module (NM-4B-U), then we can theoretically go for a max of 4 x NM-4B-U on a 3845 router. Right? Or is it possible to mix NM-4B-U and NM-8B-U together in one router?
4. Is it practical to encrypt data between the ATM and the main branch? Or it does not make sense as the ATM by itself encrypts data? If encryption makes sense, then should i also encrypt the data between ISDN links too?
5. Are there any issues using ISDN U-Based Network modules or is it better to stick with ISDN S/T- based network modules?
Thanks and Regards