Cisco Catalyst Cisco 4500 – Does Catalyst 4500x-16s Support 10/100 Network Devices?

Is a broadcast ping to the subnet from the SVI on the switch (which is low-bandwidth), and using show mac address-table dynamic out of the question?

some-switch#show mac address-table dynamic
          Mac Address Table
-------------------------------------------

Vlan    Mac Address       Type        Ports
----    -----------       --------    -----
   1    000f.257b.ba3b    DYNAMIC     Gi1/0/49
   1    0011.254f.a5be    DYNAMIC     Gi1/0/49
  56    0000.0c57.aa00    DYNAMIC     Gi1/0/49
  56    0004.0ff4.8cf4    DYNAMIC     Gi1/0/49
  56    0004.0af4.c8fb    DYNAMIC     Gi1/0/5

At this point, use your ARP table to map from mac-address to IP address.

Doing this with SNMP is possible, but somewhat painful if you need to know what port each mac-address is on... use dot1dTpFdbAddress to grab the mac-addresses, dot1dBasePortIfIndex to map to interface ifIndex and then ifName to map from ifIndex to a name you'll recognize.

SDN is a bit of an umbrella term that could mean a lot of things. To say something is "hardware ready for SDN" sounds like some marketing at best. They could be referring to OpenFlow which would have some specific hardware requirements. Cisco's onePK is mostly dependent on support within the IOS/NX-OS image, so there's a good chance it will find its way into all platforms, eventually. Until onePK goes into general release, it's hard to say definitively.