Incomplete MAC in ARP table

[adkozera]

EDIT: Hi, the issue was resolved, i was using DHCP snooping and it was not working just fine, I reconfigurated it and it works perfectly now. Thanks for all the replies!

Hi,

I am having a problem with "Incomplete MAC" address in my ARP table in Cisco Packet Tracer.
I have no idea what caused it because it worked just fine last week.

I am using DHCP on sub-interface on VLAN 4 for my Student PCs, the issue is not DHCP server, its ready to send out DHCP Pack.

Internet | 192.168.0.2 | - | Incomplete ARPA | GigabitEthernet0/0.4

Configuration for my router:

ip dhcp pool Student

network 192.168.0.0 255.255.255.0

default-router 192.168.0.254

dns-server 8.8.8.8

interface GigabitEthernet0/0.4

encapsulation dot1Q 4

ip address 192.168.0.254 255.255.255.0

Any help will be appreciated,

Adrian

[Flavio Miranda]

@adkozera 

 What is connected on the interface igabitEthernet0/0.4 ?

ARP incomplete can be caused by layer2 connectivity issue. Considering a PacketTracer and considering it was working before, you can try to close the project and open again. It can be a fail on the software.

[adkozera]

Hello Mr. Miranda,
I tried several times closing and re-opening packet tracer, however it doesnt seem to fix the issue.

Interface G0/0.4 is for Student PCs that are connected through MLS to my classroom Switch where the PC is located.

[Flavio Miranda]

I am assuming Student PCs is not a PC right? It is a router´s interface?  You should be using "encapsulation dot1Q 4" only if you are doing router on a stick topology. Which I am failing to identify looking the print. 

[adkozera]

G0/0.4 is a sub-interface for IVR-ROS, it's in the same subnet as my DHCP Server which is for my Student PC VLAN.

[Flavio Miranda]

Got. 

 I would try to reload the Router then. 

[M02@rt37 · Accepted solution]

Hello @adkozera 

Please ensure that the student PC is correctly configured to obtain an IP address via DHCP. If the PC hasn’t received an IP address yet, it would not respond to the ARP request, causing the "Incomplete MAC" status.