Today want to know about the arp protocol, encountered a problem,

I'll find a lot of data, the arp broadcast, destination Ethernet address should be 0, 1 is why I grab bag

CodePudding user response:

Arp protocol is cut in radio, of course, is 1

CodePudding user response:

The purpose of zero is not the original address, broadcast mode address must be 1

CodePudding user response:

Just started to learn when I was told that there was a address is the broadcast address,,, 255.255.255.255

CodePudding user response:

ARP destination address is the broadcast address

CodePudding user response:

You said your specific experiment, the target MAC is all zeros

CodePudding user response:

reference 5 floor jsjsboy reply:

you said your specific experiment, the target MAC is indeed all 0

I caught, it is a Gratuitous ARP, ARP without cause, destination IP address for itself,
Can be used to detect duplicate address

CodePudding user response:

I also try to catch up, but invincible arp is all 0.

CodePudding user response:

Free arp packet source IP and destination IP is oneself, the source MAC address for their MAC, destination MAC all is zero, because it to detect in the LAN IP conflict, equivalent to ask everyone: I want to use the IP address, there are others in use? The arp request is in the case of a known IP address to end, because need to carry on the layer 2 encapsulation destination MAC address, thus the source host in the network q: MAC address is the IP address is XXXX? Because it does not know the destination MAC and set the destination MAC made 1 (MAC address all 1 said in the broadcast), let all hosts receive the request within the local area network (LAN), but after receiving the request will be their own IP address and destination IP address in the message, if not consistent, do not respond, but also according to the source IP address and source MAC address of the packet to find native arp table, if there is no corresponding items in the table will be the corresponding item to join this machine in the arp table; If the destination IP is the same as the native, respond to this message, source IP for the machine IP source MAC for the native MAC, purpose IP for the request host IP, MAC is, after you receive the request to the host, adding the corresponding item in the arp table, you can proceed to the layer 2 encapsulation

CodePudding user response:

The building Lord, you found the problem cause? Can share? I recently in the study of gratuitous arp, the information from the Internet to find in the picture, most of them are all zero, there are two is all 1, I'm very curious about this question,
Couldn't resist teasing: this building is a two read the problem of the building Lord, 9 were blind force force,

CodePudding user response:

The arp message was really weird, don't you construct a message ah

CodePudding user response:

Free ARP is all F general network equipment, PC free ARP to 0, all

CodePudding user response:

The difference is that the request if the destination IP address and source IP address!