We have implemented DHCP snooping Binding on our Csico 3750 Switch for one of our User VLAN. I have noticed that I get the entries for most of the machines in the DHCP Snooping Binding Table , but some machines the entry does not appear.
I have checked these PC and they are not assigned static IP to the machne , as well as the config of the PC is same
I am sorry but I do not see how disabling the insertion of the DHCP Option 82 may resolve the original issue. Moreover, the DHCP Snooping benefits greatly from the insertion of the option-82 and I personally strongly discourage from deactivating it.
I recommend verifying the following:
In which VLAN are the ports whose clients do not get recorded in the DHCP Snooping database? Is the DHCP Snooping activated for this particular VLAN using the command ip dhcp snooping vlan X?
Are these ports treated as DHCP Snooping untrusted ports? They must not be configured with the command ip dhcp snooping trust
Are the stations connected to these ports guaranteedly getting their IP address via DHCP? Can it be confirmed using a packet sniffer on those stations, say, Wireshark?
If none of these suggestions helps then debugging the DHCP Snooping may be helpful. These commands can be used for DHCP Snooping debugging:
debug ip dhcp snooping event
debug ip dhcp snooping packet
Note that the debugging shall be preferably done in periods of low traffic, as it is CPU-intensive and may disrupt the proper operation of your networking device under higher loads.
We have the same problem, but with IP phones only. Workstations get IP and are added to DHCP Snooping Binding. But IP phones and workstations connected to network through switch of phone sometimes haven't been added to DHCP Snooping Binding. I can't understand why. I have restarted port and phones was added to the table, I restarted switch and phones which were in the DHCP Snooping Binding Table - disappeared, and vice versa. We would like to implement Dynamic ARP Inspection, but we can't... May be somebody have solved such problem and can give a hint.
Hi everyone, I would like to thank you in advance for any help you can provide a newcomer like myself!
Im studying the 100-105 book by Odom and am currently on the topic of Port security. I purchased a used 2960 and I'm trying to follow a...
While deploying a number of 18xx/2802/3802 model access points (APs), which run AP-COS as their operating platform. It can be observed on some occasions that while many of their access points were able to join the fabric WLC withou...
I am going to design and build an LAN network under a tunnel underground with long distance between the switches.
I will have 2 Catalyst switches and 8 Industrial IE3000, and they will be connected with fiber.
For now I am planning on use Layer-2 s...