Ask Your Question

Question about ARP protocol

asked 2020-03-10 06:03:43 +0000

agneta1234 gravatar image

Question about ARP protocol. In this video (from 0:25). Can someone explain why in 15th and 16th frame there is ARP protocol again, asking for MAC address, if that node already knows the MAC address (from the first and second frame) and it's even in the destination? Is it something with aging or second node just wants to check first nodes MAC address (is it still the same)?

edit retag flag offensive close merge delete

2 Answers

Sort by ยป oldest newest most voted

answered 2020-03-11 14:10:03 +0000

hugo.vanderkooij gravatar image

It's a choice. Historiclly it was common to learn ARP as soon as you got a packet. As everyting what you need is in the SYN packet as soon as it arrives there is no point to ask for it it return a SYN/ACK packet.

Historically this make a lot of send if you have a lot of systems in 1 collision domain. But times have changed and so is the size of the average collision domain. So now you (sometimes) see both ends do ARP request for just a single TCP connection.

I understand this migh look akward but that is the way I have seen ARP packet change over the years.

edit flag offensive delete link more

answered 2020-03-10 12:41:49 +0000

Chuckc gravatar image

updated 2020-03-10 12:44:18 +0000

It's difficult to see with all the 1's in the IP address.
Packets #1 and #2 are probably the ".11" node asking where the ".1" node before sending a ping.

Packet #15 and #16 are ".1" asking where ".11" is in order to send a ping response.
(Guessing that is ping traffic based on the rest of the packets in the list.)

#1: Who has Tell
#2: is at 08:00:27:e9:b4:2f

#15 Who has Tell
#16: is at 08:00:27:ef:bf:5e

If the nodes are on a /24 network the ping traffic is probably going through to reach

edit flag offensive delete link more

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

Question Tools


Asked: 2020-03-10 06:03:43 +0000

Seen: 613 times

Last updated: Mar 11 '20