PDN Control

PDN Control

Last updated: June 18, 2012

This section is only applicable to the lab application.

PDN Index

Description

PDN Index allows you to assign an Access Point Name (APN) for each PDN supported by testset, so as to determine which PDN to be connected with UE, by matching the APN requested by the UE and the APN setting specified in the testset.

You can determine which PDN to be used as follows: when the testset handles the PDN connection request from UE, the testset uses APN sent by UE to match the APN settings and uses the corresponding DUT IP settings ( DUT IP Version, DUT IPv4 Address, DUT IPv6 Prefix, etc) to establish the PDN connection.

The APN settings and APN Mapping procedure are invalid when external EPC is connected, in which the PDN connection is determined by the EPC, not eHRPD in the testset.

Configurable Parameters

  • Access Point Name

    Access Point Name setting is used to identify a Packet Data Network (PDN) that an UE wants to communicate with. When receiving the PDN connection request from UE, testset will use the APN requested by UE to match the APN settings, and use the corresponding DUT IP settings ( DUT IP Version, DUT IPv4 Address, DUT IPv6 Prefix, etc) to establish the PDN connection.

    The testset supports three PDN connections and provides three Access Point Name settings correspondingly. Each APN setting corresponds to a PDN and a set of IP-related settings, including DUT IP Version, DUT IPv4 Address, DUT IPv6 Prefix. For example, APN2 corresponds to DUT IP 2 version, DUT IPv4 Address 2, and DUT IPv6 Prefix 2.

    When UE attempts to establish a PDN connection, the testset will compare the APN setting and the APN sent by UE. If a specific APN is matched, the testset will use the correponding IP-related settings to establish the PDN connection.

    The format of APN is different between OTA signaling and your input. APN consists of one or more labels. In OTA signaling, each label is coded as a one octet length field followed by that number of octets coded as 8 bit ASCII characters. The format of APN for your input is usually displayed as a string in which the labels are separated by dots, e.g. "label 1, label 2, label 3".

    Access Point Name setting can be changed from GPIB command only. The GPIB command parameter is an ASCIIstring with a maximum length of 99 octets. The testset will not check the format of the input string yet treat each dot (".") as a separator, and encode the dot-separated string according to standard before sending it to UE. According to standard, each label of APN consists only of the alphabetic characters (A-Z and a-z), digits (0-9) and the hyphen (-), and each label begins and ends with either an alphabetic character or a digit.

    The Access Point Name 1 setting is fixed as the default APN in the testset. When the testset receives a VSNCP Configure-Request message from UE that includes a null-string APN, the testset will use the Access Point Name 1 setting as the default APN in the VSNCP Configure-ACK message sent to the UE.

       
    NOTE

    You can view the first 33 characters of Access Point Name setting in Access Point Name for Display on the testset screen at most.


       

  • VSNCP Enhancements

    If the UE had already established a PDN connection with the test set, the test set will keep the PPP and VSNCP context. See Partial HSGW Context Available State for more details. In such case, if the UE sends a VSNCP configuration request to the test set, the test set will perform differently based on two scenarios:

    • If the Attach Type in the VSNCP Configuration Request message is Initial Attach, the test set will release the existing VSNCP context and re-create a new VSNCP context with the UE. This is applicable to the test set working in either stand-alone eHRPD mode or EPC-connected mode.
    • If the Attach Type in the VSNCP Configuration Request message is Handoff Attach, and the test set is working in stand-alone eHRPD mode. the test set will execute the APN mapping procedure: If the VSNCP context requested by the UE is the same with the current context kept in the test set, the test set will acknowledge the UE and still use the current context. Otherwise, the test set will release the current context and recreate a new one according to UE's request.

       
    NOTE
    The test set does not support the scenario that the Attach Type is Handoff Attach and the test set is working in EPC-Connected mode.

       

Resyncronize PDN

Description

After the eHRPD session and PDN connectivity is established, the testset can initiate a PDN resynchronization to update the parameters (DUT IPv4 Address, DUT IPv6 Prefix, DUT IPv4 DNS, DUT IPv6 DNS, DUT IPv6 P-CSCF address) negotiated during initial PDN setup, by sending a VSNCP Configuration-Request message to the connected UE.

Configurable Parameters

  • VSNCP resynchronization

    VSNCP resynchronization is an immediate action per PDN connection, to initiate a PDN resynchronization to update the UE of parameters. The testset supports three VSNCP resynchronization actions corresponding to three PDN connections. The PDN connection can be resynchronized independently. When a specific VSNCP resynchronization action is executed, the testset sends a VSNCP Configure-Request (PDN-ID) to resynchronize the PDN context which is bound to that PDN-ID.

    VSNCP resynchronization is an asynchronous operation. As the testset interface is not locked during the resynchronization for a PDN connection, you can perform resynchronization for three PDN connections simultaneously.

    When VSNCP resynchronization finished, UE and the testset will have the PDN context resynchronized, and UE will be notified of certain updates as IP address, P-CSCF address. If VSNCP resynchronization fails, the corresponding PDN connection will be dropped. You can check the resynchronization procedure using WPA logging.

  • PDN Index

    PDN Index displayed on the testset interface helps you select the optimal PDN operations based on the PDN index value.

    The testset supports three PDN connections with the PDN Index range from 1 to 3. When the value is changed, you can refer to the updated testset interface which shows the corresponding PDN operations banded to PDN.

       
    NOTE
    PDN Index is different from In Use PDN Identifier, which is assigned by the testset when a PDN connection is established between UE and the testset.

       

Disconnect PDN

Description

After the eHRPD session and PDN connectivity are established, either UE or network can initiate the PDN disconnection from the network side, by sending a VSNCP Terminate-Request message to the peer.

The PDN connection can be terminated independently. The testset supports three PDN termination actions.

Configurable Parameters

  • VSNCP Termination

    VSNCP Termination is an immediate action per PDN connection, to initiate a PDN context release procedure. When a specific VSNCP Termination action is executed, the testset will send a VSNCP Terminate-Request (PDN-ID) to release the PDN connection bound to the PDN-ID.

    VSNCP Termination is only applicable when Application Type is Alternate EMPA, corresponding PDN connection is established (PDN Identifier is not NAN), External EPC Connection Status is Disconnected, and External PDSN State is set to off.

    When the testset finds that all PDN connections have been terminated, if Keep Partial HSGW Context is off, the testset will initiate LCP termination procedure to drop the data connection.

Enable/Disable Router Advertisement message

Description

After the UE has successfully negotiated with VSNCP to generate an IPv6 PDN, the testset will send the IPv6 Router Advertisement (RA) message to the UE which includes the UE's home network prefix, so the UE can generate an IPv6 address.

The feature of disabling Router Advertisement disables the testset to send the RA message, so the UE will never be assigned an IPv6 address.

UE has the option to send Router Solicitation (RS) messages to ask for RA message. When the UE has sent the maximum number of RS messages, it will terminate the PPP session.

Configurable Parameters

  • IPv6 Router Advertisement Enabled .

    IPv6 Router Advertisement Enabled controls whether Router Advertisement (RA) message will be sent to the connected UE, when the testset performs the IPv6 address negotiation with UE.

    As a part of IPv6 address allocation procedure, UE may send a Router Solicitation (RS) message to the testset. Upon receiving the message, or anytime after VSNCP negotiation finished, the testset should send Router Advertisement (RA) message including the UE's IPv6 prefix to the UE, so UE can generate an IPv6 global unicast address via IPv6 stateless address auto-configuration