You can add a DHCP Server Node test case to a GPRS test and provide DHCP address allocation services for the test session. The server node can respond to a GGSN that acts as a DHCP client, or to a GGSN that acts as a relay agent for DHCP clients simulated by the GGSN Nodal test case.
In general, defining a DHCP server node consists of the following steps:
Before you configure a DHCP server node, you should have a basic understanding of:
The following information will be used in the server node definition:
The MN addresses that will be allocated by the server node
User Class values that will be included in request messages from the client (when the GGSN is a client)
The IP address that the GGSN uses for DHCP traffic (when the GGSN is a relay agent)
Start with a test session that you have successfully executed with the GGSN SUT.
Open the test session and add a DHCP Server Node test case. If possible, assign the test case to a different test server than is assigned to the GGSN Nodal test case. This will allow the GGSN Nodal test case to achieve its full capacity.
Enter the Number of Sessions... that will be supported by the server node.
Define the DHCP server emulator with an IP address that is reachable by the GGSN.
Select the IP Address Type that will be used in the test: IPv4 or IPv6. The DHCP Server Port will be automatically provisioned with the default DHCP port for the address type. If the GGSN sends to a different DHCP port, modify the default accordingly.
In an IPv4, test you can include the renew and rebind timers... in responses to the client by checking the Include T1 Option or Include T2 Option checkboxes respectively.
The Wait Request Msg Time... defines the number of milliseconds the server node will wait for a response to an address offer before releasing the reserved address back to the pool. The default value is one second. You can increase this value if network latency may cause a delay in client responses.
Define the server node's address pools following the instructions in Using the IP Pool Manager.
Apply the server node test case. If any parameter definitions fail validation, you will receive an error message indicating which parameter must be corrected.
If the MNs will be generating DHCP client requests, with the GGSN acting as a relay agent, add a DHCP client to the GGSN Nodal test case and configure the client according to the server node definition.
Run the test session, and you should see the PDP contexts establish as they did in previous tests. The DHCP report tab records the types of messages sent and received by the server node and DHCP transaction errors, the IP Pool Manager tab reports IP address allocation processing, and the DHCP Server Node tab reports the processing throughput of the server node.
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TROUBLESHOOT: If your contexts fail to establish, look for Discovers Received (IPv4) or Solicits Received (IPv6) on the DHCP tab. If the server node is not receiving discovery messages, the GGSN may not have connectivity with the server node or it may not be directing DHCP traffic to the server node's IP address. Connectivity problems are also indicated by Wait Request Timeouts, which means that the server node is not receiving responses to its offer messages. If the server node records messages sent and received, it may not be able to allocate IP addresses. Look for Mismatch Requests Received or Poorly Formed Received, which indicate that invalid client requests are preventing address allocations. The IP Pool Manager report tab records errors encountered during the allocation process when the client's messages are valid. Allocate Fails Pool Empty indicates that the client properly requested a pool but the pool has no addresses available, or that the pool selected by default has no addresses available. Allocate Fails Pool Not Found indicates that the client is requesting an address from a specific pool but the server node cannot find a matching pool identifier. If you are using a DHCP client in the GGSN Nodal test case, Adding a DHCP Client includes troubleshooting tips for the client side. |