Automatic updates for IP address allocation/de-allocation

During the subscriber-host setup phase, the first allocated IP address is sent in the CCR-I message from the node to the PCRF.

Each subsequent IP address allocation or de-allocation for the same host can optionally trigger a CCR-U, notifying the PCRF of the IP address allocation/de-allocation event.

This behavior can be enabled via the following CLI command:

configure
    subscriber-mgmt
      diameter-application-policy <pol-name>
        gx
          [no] report-ip-addr-event

The IP address allocation/de-allocation event driven CCR-U message carries the respective event code [UE_IP_ADDRESS_ALLOCATE(18) or UE_IP_ADDRESS_RELEASE(19)] along with the corresponding IP address.

The IP address allocation/de-allocation events are applicable to the following addresses:

• Framed-IP-Address (AVP Code 8) IPv4

• Framed-IPv6-Prefix (AVP Code 97) SLAAC

• Delegated-IPv6Prefix (AVP Code 123) IA-PD

• Alc-IPv6-Address (AVP Code 1023) IA-NA

These event-codes are only sent in CCR-U messages and not in CCR-I and CCR-T messages (when the host is instantiated and terminated).

Examples:

• IPv6 attachment request arrives with two IP addresses: IA-NA and IA-PD. This is a new host. CCR-I is generated with two IP addresses included (IA-NA and IA-PD, assuming that request for their allocation is carried in the same DHCPv6 message).

• Afterward, the attachment request for an IPv4 address arrives on the same host. CCR-U is generated with the event UI_IP_ADDRESS_ALLOCATE and corresponding AVP (framed-address) is sent to the PCRF. No IP address other than this new IPv4 address is sent.

• RAR is received for the (any) policy change. The node replies with RAA and it contains all three IP addresses (AVPs) that have been allocated to the host.

If the IP address notification event is enabled, the node-originated Gx message carries all known IP addresses/prefixes associated with the subscriber-host (Gx session), unless those messages contain one of the two event codes:

UE_IP_ADDRESS_ALLOCATE(18) or UE_IP_ADDRESS_RELEASE(19).

If one of those two events is present in the Gx message, the IP address/prefix carried in that message is only relevant to the event contained in the message (address/prefix allocated or released).

If the IP address notification event is disabled, the node only sends the IP address from the first host. This IP address is included in all messages related to the Gx session. If this IP address is removed (de-allocated) mid-session from the dual-stack host, the node stops advertising it, or any other address, from Gx messages for that particular session.