I have created a simple topology with routers and computers and I ping from computer A to computer B . Firstly, computer A send ARP request to gateway of A and then got reply. Mac and ip of gateway is addes to arp table of computer A. Then ICMP packet is send ( let's say to router X) . Later, I got reply on computer A from computer B , which comes from router Y, but mac and ip of router Y isn't added to arp table of computer A.
Is it right behaviour or I misconfigured something ?
Ping Reply and ARP Table – Network Troubleshooting
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Your reasoning is the wrong way. TCP/IP handles the layers top down, not bottom up.
PC A will first do a lookup in the routing table and decide that the only way to reach PC B is via the router specified in that routing table.
If the MAC address of the router is unknown it will send an ARP request to figure out which MAC address corresponds to the gateway IP.
Then the frame (containing the IP packet) will be sent to the MAC address of the router which will do a lookup in its routing table to see on which interface PC B is connected or via which next hop it should be routed. Assuming PC B is connected to another interface of the router the router will do a lookup (and if needed an ARP request) to figure out the MAC address of PC B and then forward the frame.
GLBP doesn't use gratuituous ARP. When someone asks which MAC does the virtual IP have, the AVG will reply saying "This IP is at this MAC", using the field "Sender MAC Address", which is invisible to the switch's CAM table. The source address is still the AVG MAC.
EDIT: I said it wrong. The IP address requested is actually the Sender, the Target address is the address of the host that sent the arp request in the first place. I'll just upload here an example of ARP Request and Reply and when I get home I'll simulate on GNS so you can see how it really works and not just an example capture.
Cadant device asks which is the MAC for x.x.128.77 and if anyone has the answer, please direct it to x.x.128.164.
Oracle device then replies with a broadcast saying that x.x.128.77 is himself, at the MAC 00:14:4f:fb:c3:16, at the sender MAC address. The target is x.x.128.164, who was the one requesting.
If this was the case of a GLBP host, it would state the virtual MAC in the sender MAC address field. It's called Proxy ARP. Just hold tight, I'll upload the actual GLBP capture in about 10 hours.
GLBP Capture:
R2 is the AVG, R1 the AVF:
HOST 192.168.0.200 asked for the MAC of 192.168.0.1, the GLBP VIP. He received an answer from C001.3270.0000, which is the real MAC of the interface fa0/0 from R2, stating that 192.168.0.1 was located at 0007.B400.0101, one of the virtual MAC .
Later on, HOST 192.168.0.201 asked for the MAC of 192.168.0.1 and received an answer from the same C001.3270.0000 saying that this IP was with the MAC 0007.B400.0102, the other virtual MAC. Wireshark even throws a yellow line saying that "Hey, lookout, this IP is in use by another host".
When issuing "show glbp" from both routers, the AVG output have a little more detailing, including how many times it answered and ARP request with this or that virtual MAC address. You can see the MAC and IP addresses of the interfaces in "Group Members", present in both outputs.
Best Answer
Network devices can only see MAC addresses of devices on the local network (broadcast domain, actually.) ARP traffic is broadcasted and not routed. When your Computer A is trying to communicate with Computer B on a different network, it doesn't need to know the MAC address of B. It only needs to know how to route to that IP address and the MAC address of the local router.