DHCP Forwarder Application
Published: February 25, 2015
This chapter describes how to install the DHCP forwarder application as well as adding and removing resources.
Note This module is relevant only when the DHCP Lease Query Login Event Generator (LEG) or the DHCPv6 Lease Query LEG is installed on the Cisco Service Control Subscriber Manager server. See the “DHCP Forwarder Application Enhancements for DHCPv6” chapter.
The DHCP Forwarder application acts as a bridge between the DHCP Lease Query LEG and the DHCP servers. The LEG sends a request to the DHCP Forwarder, which then forwards the request to the appropriate DHCP server. The DHCP Forwarder passes the replies from the DHCP servers to the LEG. The LEG signals the forwarder which server should receive each request. Therefore, no special configuration is needed for this application.
The DHCP Forwarder runs with root privileges; because only those applications that have root privileges can open ports below 1024. DHCP uses ports 67 and 68. No other application must use these ports.
Installing the DHCP Forwarder
Note If you are performing a fresh install of the Cisco Service Control Subscriber Manager, manually install the DHCP forwarder by following these steps.
Step 1 Run the DHCP Forwarder installation script from the SM DIST root directory.
Run the installation script as root.
The installation script extracts DHCP Forwarder distribution to the sm-inst-dir \sm\server\addons\dhcp-forwarder directory ( sm-inst-dir refers to the Subscriber Manager installation directory). The script adds the initialization scripts to their location according to the operating system running on the machine.
Step 2 (Optional) Confirm that the following ports are not being used by any other application:
- DHCP—67, 68
- DHCPv6—546, 547
Step 3 Run the DHCP Forwarder application.
This application can be run using one of the following methods:
- Restart the machine. The initialization script will start the application automatically.
- Run the following command as root :
Note It is not possible to run the install-forwarder.sh script if the /etc/motd file exists. The file should be moved or removed prior to running the script. Use the ps -eaf | grep DHCP command to view the running process of the DHCP Forwarder.
Uninstalling the DHCP Forwarder
Step 1 Start the DHCP Forwarder.
Step 2 Run the DHCP Forwarder installation script as root from the SM DIST root directory.
Upgrading the DHCP Forwarder
If you upgrade the Cisco Service Control Subscriber Manager from any previous version to version 4.1.0, DHCP forwarder is also upgraded automatically, if DHCP forwarder is already installed. If DHCP forwarder is not already installed, install it manually. For more details on how to perform a fresh install of DHCP forwarder, see the “Installing the DHCP Forwarder” section.
After the Cisco Service Control Subscriber Manager is upgraded, DHCP forwarder starts automatically if the DHCP Forwarder process is already running.
DHCP Forwarder Veritas Cluster Server Agent
To verify that the DHCP Forwarder process is active at all times, a Veritas Cluster Server (VCS) Agent of type OnOnlyProcess is added as a resource.
Adding a DHCP Forwarder Resource
Step 1 Import the OnOnlyProcess agent's type from the /opt/VRTSvcs/bin/OnOnlyProcess/OnOnlyProcess.cf file.
Step 2 Add an OnOnlyProcess resource called DHCP_Forwarder to the service group.
Step 3 Note the path and arguments of the DHCP Forwarder.
Run the following command via a Telnet session on each of the servers:
Look for the line containing the text “DHCP_FORWARDER”. This line contains the path and arguments of the DHCP Forwarder to be used in the next step.
Step 4 Define the OnlineCmd, PathName, and Arguments parameters.
Define the parameters as follows:
- OnlineCmd —Type the DHCP Forwarder start command:
- PathName —Type the DHCP Forwarder process path (from the previous step). For example: /opt/pcube/j2re1.4.2_05/bin/java
- Arguments —Type the DHCP Forwarder process arguments (from the previous step). For example: DAPP=DHCP_FORWARDER -jar /opt/pcube/sm/server/addons/dhcp-forwarder/dhcpforwarder.jar
For further information about the parameters, see Figure 10-1.
Figure 10-1 Adding a DHCP Forwarder Resource
Note The arguments line might seem shorter than the actual full argument list. This is perfectly acceptable.
Step 5 Check the Critical and Enable parameters.
Step 6 Link the DHCP Forwarder resource with the Cisco Service Control Subscriber Manager.
Removing a DHCP Forwarder Resource
Step 1 Right-click on the DHCP Forwarder Resource icon and choose Delete from the drop-down menu (Figure 10-2).
Figure 10-2 Removing a DHCP Forwarder Resource