Manual Chapter :
Configuring the BIG-IP System for DHCP Renewal
Applies To:
Show Versions
BIG-IP APM
- 17.0.0
BIG-IP Link Controller
- 17.0.0
BIG-IP Analytics
- 17.0.0
BIG-IP LTM
- 17.0.0
BIG-IP PEM
- 17.0.0
BIG-IP AFM
- 17.0.0
BIG-IP DNS
- 17.0.0
BIG-IP ASM
- 17.0.0
Configuring the BIG-IP System for DHCP Renewal
Overview: Renewing IP addresses for DHCP clients
You can configure the BIG-IP system to manage DHCP renewal requests and responses.
Before configuring the BIG-IP system to manage DHCP renewal requests and responses, it is
helpful to understand some BIG-IP system terminology:
BIG-IP object type |
Definition |
|---|---|
BIG-IP pool member |
A DHCP relay target (such as a DHCP server or BOOTP server). This is the dynamic
address server to which the BIG-IP system forwards unicast requests. |
BIG-IP virtual server |
A BIG-IP system address on the listening VLAN |
BIG-IP VLAN assigned to a virtual server |
A listening VLAN, controlled on a per-virtual server basis |
About DHCP renewal
You can configure the BIG-IP system to act as a DHCP renewal system. A
common reason to configure the BIG-IP system as a renewal system is when the DHCP servers
reside on a different subnet than that of the client systems, and the BIG-IP system is also
configured as a DHCP relay agent. As a DHCP renewal system, the BIG-IP system manages the
renewal of client IP addresses by DHCP servers before the addresses expire.
During the renewal process, a DHCP client sends a renewal request, which
is passed through a BIG-IP Forwarding IP type of virtual server directly to the specific
DHCP server that issued the initial client IP address. The DHCP server then sends a
response to renew the lease for the client's IP address.
In the example shown in the illustration, a DHCP client sends a renewal
message to the same BIG-IP system that initially acted as the DHCP relay agent. This
renewal request is forwarded through a BIG-IP renewal virtual server directly to DHCP
server 1. DHCP server 1 then provides a response to renew the lease for the client's IP
address.
A sample DHCP
renewal system configuration
Creating a DHCP renewal virtual server
A Dynamic Host Configuration Protocol (DHCP) renewal virtual server forwards a DHCP
request message from a DHCP client directly to a DHCP server, to automatically renew an
IP address before it expires.
- On the Main tab, click .The Virtual Server List screen opens.
- ClickCreate.The New Virtual Server screen opens.
- In theNamefield, type a unique name for the virtual server.
- Type a description for the virtual server.
- From theTypelist, selectForwarding (IP).
- For a host, in theDestination Address/Maskfield, type an IPv4 or IPv6 address in CIDR format to allow all traffic to be translated.The supported format is address/prefix, where the prefix length is in bits. For example, an IPv4 address/prefix is0.0.0.0/0, and an IPv6 address/prefix is::/0.
- In theService Portfield, type67(IPv4) or547(IPv6).
- From theProtocollist, selectUDP.
- From theVLAN and Tunnel Trafficlist, select the VLANs on the same network as the DHCP clients.
- ClickFinished.
The BIG-IP system is now configured with a virtual server that can forward DHCP renewal requests directly to the appropriate DHCP server.
Implementation result
The BIG-IP® system is configured to forward DHCP client renewal requests to appropriate DHCP servers that reside on a different subnet than the client systems. The BIG-IP also forwards the DHCP server responses back to the client systems, therefore ensuring that client IP addresses do not expire.
