Given the network constraints with a Layer 3 MTU of 8900, the recommended MTU setting for the ASA C250 when used with iSCSI on ESXi 8 would be to match this constraint, setting the MTU to 8900 bytes. ...Given the network constraints with a Layer 3 MTU of 8900, the recommended MTU setting for the ASA C250 when used with iSCSI on ESXi 8 would be to match this constraint, setting the MTU to 8900 bytes. However, due to the additional overhead from TCP/IP and iSCSI headers, it necessary to set the MTU slightly below the maximum to ensure there is enough room for this overhead.