What is a difference between Predefined NAT and Bulk port allocation ?

[Yanes ABDELLI]

In order to track subscribers, I need to know the difference between the BPA (Bulk port allocation) and the Predefined NAT in IOS XR.

The BPA is not available in a Predifined NAT, so how can I set a range of ports for each subscriber with the corresponding Public IP address.

Thank you.

[Nitin Pabbi]

Hi,

BPA is used for reducing logs generation by providing single predefined port for a range of ports in a sequences.

ex: 1-10 contiguous ports  will be assigned with single per-allocated port from 1-10 range of ports.

this logic help in reduce logging.

on the other hand Pr-defined NAT is a feature which maps private address to port/s and inturn to satellite public IP addresses. feature BPA cant be use with pr-defined NAT.

<<<<<< BPA is not available in a Predifined NAT, so how can I set a range of ports for each subscriber with the corresponding Public IP address.

You can;t set such port range because port range is picked randomly based on inherited algorithm in pre-defined NAT feature. 

You can use below CLI to know the mapping details :-

show cgn nat44 nat1 mapping inside-address inside-vrf Inside_1 start-addr <> end-addr <>

Thanks

Nitin Pabbi

[Yanes ABDELLI]

Thank you very much for your reply :D