OK guys , i found some info on this in the

"Integrating the Cisco Catalyst Blade Switch 3020 for the HP c-Class BladeSystem into the Cisco Data Center Network Architecture" Design Guide on Cisco site. But additional info i always welcome

Out-of-Band Management

OOB management is the practice of dedicating an interface on the managed device for carrying management traffic. It is also the recommended management method for blade systems. OOB management isolates the management and data traffic and provides a more secure environment.

The Cisco Catalyst Blade Switch 3020 contains an additional Fast Ethernet port, which connects to the HP c-Class BladeSystem Onboard Administrator, providing OOB management using the insight manager interface. The user may also use this path to access the CLI functions of the switch, transfer SNMP information, and upload software images and configuration files. This path is independent of the switch fabric. This Fast Ethernet port defaults to a Dynamic Host Configuration Protocol (DHCP) client from a DHCP server either as part of the Onboard Administrator or external on the network attached to the enclosure. The user can also set a static IP address for the Fast Ethernet port.

By default, the Cisco Catalyst Blade Switch 3020 provides no routing functions and can have only one default gateway defined. Even though the Fa0 interface is called “routed”, it cannot route user traffic. Therefore, if you enable multiple SVIs or enable the Fast Ethernet port, you will not be able to access all these interfaces from other subnets. The recent migration (12.2(22)SE) of the Cisco Catalyst Blade Switch 3020 from the LANBase image to IP Base provides basic Layer 3 routing (RIP and Static Routing and EIRGP Stub).