Filter
Top Products
22-17
Cisco CNS Network Registrar User’s Guide
OL-6240-02
Chapter 22 Advanced DHCP Server Properties
Configuring Virtual Private Networks and Subnet Allocation
In the CLI—To import leases, use import leases filename. Each lease entry in the file can include
the VPN at the end of the line. If it is missing, Network Registrar assigns the [none] VPN. (See also
the “Importing and Exporting Lease Data” section on page 21-3.)
nrcmd> import leases leaseimport.txt
To export the address or lease data to include the VPN, use export addresses with the vpn attribute,
or export leases with the –vpn option. The VPN value can be the reserved word global or all:
–
Global—Any addresses outside the defined VPNs (the [none] VPN).
–
All—All VPNs, including the [none] VPN.
If you omit the VPN, the export uses the current VPN as set by session set current-vpn. If the
current VPN is not set, the server uses the [none] VPN.
nrcmd> export addresses file=addrexport.txt vpn=red
nrcmd> export leases -server -vpn red leaseexport.txt
• Scopes—Scopes can include the VPN name or its ID, as described in the “Creating Virtual Private
Networks” section on page 22-14.
–
In the local cluster Web UI—Click DHCP, then Scopes. Create or edit a scope and set the
Miscellaneous attribute vpn-id.
–
In the regional cluster Web UI—Click DHCP Configuration, then Scope Templates. Create or
pull, and then edit a scope template to set the Miscellaneous attribute vpn-id.
–
In the CLI—Use the scope creation and attribute setting commands. For example:
nrcmd> scope examplescope1 set vpn=blue
nrcmd> scope examplescope1 set vpn-id=99
• Subnets—Listing subnets, showing a subnet, or getting the vpn or vpn-id attribute for a subnet shows
the VPN. See the “Configuring DHCP Subnet Allocation” section on page 22-17.
• DHCP server—If the vpn-communication attribute is enabled (which it is by default), the DHCP
server can communicate with DHCP clients that are on a different VPN from that of the DHCP
server by using an enhanced DHCP relay agent capability. This capability is indicated by the
server-id-override suboption in the relay agent information option (82).
Configuring DHCP Subnet Allocation
The following section provides an example of setting up subnet allocation using the DHCP server.
Figure 18-5 on page 18-6 shows a sample subnet allocation configuration with subnets assigned to
provisioning devices, along with the conventional DHCP client/server configuration. The subnet
allocation feature is available only in the CLI and not in the Web UI.
Before allocating subnets, the DHCP server first determines what VPN the client is on, in the following
order:
1. The server looks for incoming VPN options and uses the value for the VPN.
2. If no VPN options are found, the server uses the relay agent suboption value, then combines the VPN
with the subnet address to form the unique identifier.
3. If no relay agent suboption is found, the server looks for client-class information (selection tags).