question into routing in ccnp r&s to mr/keith bogart












hello my sir


 


iam into your lecture :-

33 - Basic Switch Configuration & Verification  Part 3

 


as you say into this example  that R2 will send broadcast arp msg to r1


 to know his own mac address


but into brodcast it`s FFFF.FFFF.FFFF


NOW AS YOU SEE INTO THIS EXAMPLE WHY R2 SEND 0000.0000.0000


 (AS YOU SEE INTO RED


MARK) NOT SEND IT FFFF.FFFF.FFFF? WHY HE`S DOING THAT?


 


ALSO INTO GRATITUOUS ARP PROTOCOL , YOU SAY THAT


 R2 SEND REPLY BROADCAST


MESSAG WITHOUT ANY REQ ? WHY R2 DO THAT?


 


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answer from mr/keith bogart

 




Hi Mohammed,
 
Your question is a great example of why I always recommend that people obtain actual packet captures (Sniffer traces) to really understand how protocols work.
 
In the output of “debug arp” that you’ve provided, I can understand how you’d mistakenly assume that the 0000.0000.0000 represents the destination MAC address of the ARP Request…but it does not.  That part of the output is actually showing you a field within the ARP packet called the, “Target MAC Address” field.
 
See below from an ARP Request packet capture:
 
 



image











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