Users Guide

View the DHCP binding table
OS10# show ip dhcp binding
IP Address Hardware address Lease expiration Hostname
+--------------------------------------------------------------------------
11.1.1.254 00:00:12:12:12:12 Jan 27 2016 06:23:45
Total Number of Entries in the Table = 1
With a fixed host configuration, also known as manual binding, you must configure a network pool with a matching subnet. The static
host-to-MAC address mapping pool inherits the network mask from the network pool with subnet configuration, which includes the host’s
address range.
In the following example, the pool host1, which is the fixed host mapping pool, inherits the subnet and other attributes from the pool
hostnetwork, which is the DHCP client IP address pool. There is no matching network pool for host2. Therefore, the DHCP client with
the MAC address
00:0c:29:aa:22:f4 does not obtain the correct parameters.
OS10# show running-configuration interface ethernet 1/1/2
!
interface ethernet1/1/2
no shutdown
no switchport
ip address 100.1.1.1/24
flowcontrol receive off
OS10# show running-configuration ip dhcp
!
ip dhcp server
no disable
!
pool host1
host 100.1.1.34
hardware-address 00:0c:29:ee:4c:f4
!
pool hostnetwork
lease infinite
network 100.1.1.0/24
!
pool host2
host 20.1.1.34
hardware-address 00:0c:29:aa:22:f4
DHCP relay agent
A DHCP relay agent relays DHCP messages to and from a remote DHCP server, even if the client and server are on different IP networks.
You can configure the IP address of the remote DHCP server.
You can configure a device either as a DHCP server or a DHCP relay agent — but not both.
If routes are not leaked between VRFs, the DHCP relay agent supports multi-virtual routing and forwarding (VRF) instances. The client-
facing and server-facing interfaces must be in the same VRF.
The DHCPv6 relay agent performs the same role as that of a DHCP relay agent, but in an IPv6 network. The DHCP relay agent forwards
the DHCPv4/DHCPv6 messages from the configured interface to the DHCPv6 server as a unicast message. The DHCP relay agent then
forwards the server’s response to the client.
When you configure DHCPv6 relay on an interface, you must:
• Configure an IPv6 address on the interface.
• Ensure that the DHCPv6 server is reachable.
Option 82 for security
DHCP, as defined by RFC 2131, provides no authentication or security mechanisms. To provide security, the DHCP relay agent supports
Option-82 with the Circuit ID sub-option, which is the printable name of the interface where the client request was received.
This option secures all DHCP traffic that goes through a DHCP relay agent, and ensures that communication between the DHCP relay
agent and the DHCP server is not compromised.
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System management