Friday 24 August 2012

What is Hardware type in ARP header ?

If You see ARP frame in Wireshark, you will notice "Hardware type" a two byte field , value given as 0x0001 ( Ethernet ). What are other hardware types defined for ARP ? Did you had any time to think about it ?

We have few more hardware types defined for ARP , and here Ethernet refers to10 Mb Ethernet.  If you go through RFC 826 the ARP RFC , they are always talking about 10 Mb Ethernet , so for Ethernet protocol the hardware type is fixed as 1 ( Ethernet 10 Mb).

Why we did not change the hardware type when Fast Ethernet or Gig Ethernet came ? Not sure . Let me know if you know the answer.

What about "Hardware type" for Wireless ARP packets between 802.11 a/b/g/n AP or station?

Well the hardware type is  1  ( Wrong or is it a Bug !) Dont have enough expertise to comment on this , so no comments on this too....Let me know if you know any reason for it . Check in Wireshark/Omniipeek for wireless packets , if you dont trust me.

Anyway you should never trust anyone if you a tester , but test it, verify it and then give your comments !!!

Back to main topic what are different hardware types defined for ARP? Here is the list , and it is defined in RFC 1060.


Hardware Type (hrd)

      Type   Description                                 
      ----   -----------                                 
        1    Ethernet (10Mb)                                  
        2    Experimental Ethernet (3Mb)                      
        3    Amateur Radio AX.25                             
        4    Proteon ProNET Token Ring                        
        5    Chaos                                            
        6    IEEE 802 Networks                                
        7    ARCNET                                           
        8    Hyperchannel                                     
        9    Lanstar                                           
       10    Autonet Short Address                          
       11    LocalTalk                                       
       12    LocalNet (IBM PCNet or SYTEK LocalNET)