what is the difference between cisco catalyst and nexus switches?Cisco Nexus and SAN Switches both are same?Cisco MDS and SAN Switches both are same?

Hi,We have configured the ssh configuration in our ASA firewall, We are able to access the asa firewall through ssh from intranet using outside interface public ip but not able to access the same through public network, even i tried (SSH 0.0.0.0 0.0....

why we didn't call frame instead of packet at l3 level which device are using MAC address ?