Hello Gowthamraj
Actually, all of the bytes found within the message are used for PIM. You will find that in the Hello packet, you have several PIM options:
These options are used by PIM to transmit specific information relative to the type of PIM message being sent. You can view all of the PIM options at this IANA reference site.
Looking at a different type of PIM message, the Join/Prune message, we see that we have other PIM options:
All of the data found within the PIM message is useful and can be examined in detail in the cloudshark capture.
I hope this has been helpful!
Laz