1. Do we really need to know mac address of a PC to ping it?
You do. MAC address is the lower (or last) level (or step) of networking. Ip address are used to find out if you are on the same network as your target, so the OS can determine if it has to send to an intermediate router or if it can send directly to the target. If the OS know it is on the same network, it does an ARP request to find out "who" the client is, otherwise it does an ARP request to find out "who" is the router. Network card can't communicate with anything but MAC address. Ip and hostname address are handled by the OS, but ultimatly, the network card need the physical address (MAC address) of the target to talk.
2. When i tried to ping the Board(which has the mac address problem) it is possible via a Hub (Inspite of the problems stated above) but not via a Router.
Now this is strange... It may be caused by various cause.
First of all, the difference between a hub and a router is that the Hub is only a "check point" that concentrate the electric signal on a network. It doesn't try to find out where the packet (I assume you know what a packet is
) is going. In fact, any packet send to a hub is sent back to each and every port; it's exactly like your cable was suddently divised into several cables. A hub is a dumb device. No CPU, no OS, it's just pure circuitry.
On the other hand, router does try to find out where a packet should go. Router are "routing" the packet to it's destination. If you send a packet to a router, the OS in the router will find out to which port it should go and send it back _only_ to this port. On course, as I said in "1-", it need the MAC address to do so. Modern router also include some feature like DHCP server and firewalling. So a router is in fact an "intelligent" device.
Bcoz the mac addresss is looking like 00:00:00:00:ff:ff and unable to do ARPING
can i come to the conclusion that the problem is only with MAC address.
Can it be due to any other problem?
Well, hard to say. It's very unclear why you can't ping throught the router but that you can throught the hub. My guess about it would be that your router is doing some filtering on MAC to prevent "illegal" MAC address on your inner network (and obliviously 00:00:00:00:ff:ff is giving him some problem). Or maybe the 00:00:00:00:ff:ff is just forbidden by <something> (standard, rfc, micro$oft or whatever) your router is respecting but not Linux ? Or maybe your Linux computer doesn't answer correctly to the ARP request (maybe it answer the real MAC address instead of the buggy one??). It's really hard to say and it would need some time to figure this out. If you want to try, you could use program like "tcpdump", "ethereal" or "iptraf" to listen to networking packet. Or (easier) just change your MAC and check if it works
In any case, you can't say that ARPING is failing because your MAC is wrong, but you can't say otherwise either. I agree it is quite suspect but it could be something else (buggy router? broken driver? interstellar aliens sending telepatic crap on your network?), who know.
For now try the fix I gave you earlier, if it fails, maybe a search on google could give you some hints...