The advanced console server families (ACM5000, ACM5500 and IM4200) have models with a second Ethernet port that can be configured for OOB (out-of-band) broadband access.This provides a secure alternate path to devices at your remote sites when your primary network is impaired; and to ensure on-site infrastructure is accessible even during system or network outages.
So with two active broadband access paths to a remote IM4200; in the event you are unable to access the remote site through the primary management network (Network 1) you can still access it through the alternate broadband path (e.g. a T1 link) on Network 2.
To set this up ensure when configuring the principal Network 1 Settings (eth0) connection, the Failover field is set to None. Then configure Network 2 Settings (eth1) with the IP settings that relate to the alternate link.