Hello Nitay
In IPv4, DHCP always builds the binding table, without the use of DHCP snooping. When you enable DHCP snooping, it will build the DHCP snooping binding table. These are two different tables. The first is used by DHCP to simply list the IP address leases that have been given out to particular hosts. You can view this table using the show ip dhcp binding
command like so:
Router#show ip dhcp binding
Bindings from all pools not associated with VRF:
IP address Client-ID/ Lease expiration Type
Hardware address/
User name
10.16.173.0 24d9.2141.0ddd Jan 12 2013 03:42 AM Automatic
10.16.173.18 24d9.214a.6dd3 Jan 12 2013 04:59 AM Automatic
10.16.173.21 24d9.214a.eee9 Jan 12 2013 03:49 AM Automatic
10.16.173.24 24d9.214a.13d6 Jan 12 2013 03:12 AM Automatic
This table includes IP lease, the corresponding MAC address of the host, the lease expiration and the type.
Now the DHCP snooping binding table is different. This table keeps track of DHCP addresses and includes information such as VLAN number and interface information. The important thing here is the interface info maintained by the table. Information on this table can be seen using several commands such as:
SW1#show ip dhcp snooping
<--output ommitted -->
Interface Trusted Rate limit (pps)
------------------------ ------- ----------------
FastEthernet0/1 no 10
FastEthernet0/2 yes unlimited
and…
SW1#show ip dhcp snooping binding
MacAddress IpAddress Lease(sec) Type VLAN Interface
------------------ --------------- ---------- ------------- ---- --------------------
00:0C:29:28:5C:6C 192.168.1.1 85655 dhcp-snooping 1 FastEthernet0/1
I know I went into a lot of detail, but I just want to be clear. Now when it comes to IPv6, DHCPv6 creates a binding table that corresponds IPv6 addresses to MAC addresses just like DHCP does. This is a fundamental part of how DHCPv6 works. But, DHCPv6 Guard, unlike DHCP snooping, does not build a DHCP snooping binding table.
I hope this has been helpful!
Laz