Host identification plays a critical role during the assignment of the parameters to the host through LUDB. The parameters that can be assigned to the subscriber host can range from the IP addressing parameters and the subscriber identification string all the way to the parameters that define the service to which the subscriber is entitled.
LUDB access in the context of IPoE hosts is triggered by DHCP messages passing through the interface on which the LUDB access is configured. This is true regardless of the direction of the DHCP message flow (ingress/egress).
The parameters that define the characteristics of the host are represented by an LUDB host entry. The parameters in the LUDB entry can be unique for each individual host, or they can be shared for a group of hosts. In the former case, the identification field for the LUDB host entry must be host specific while in the latter case the identification field for LUDB host entry could be derived from DHCP options that are common to a set of host.
The host identification in the LUDB can be based on a fixed set of predefined fields within the 7750 SR and 7450 ESS. If this predefined set of fields is not flexible enough, a custom identification field can be constructed from the DHCP options that are processed by the Python script. When this custom identifier is constructed, its value can be preserved for the duration of the DHCP transaction and it is used by the LUDB for the host identification.
An example of how this can be used is the following:
A Python script is installed in 7750 SR and 7450 ESS. This Python script intercepts incoming DHCP messages on the access side (Discover/Solicit/Request/Renew/Rebind) and consequently creates a host identification string based on DHCP options in the packet. This string then is cached and used for host identification in LUDB in both directions (access ingress and network ingress).
This functionality is supported for DHCPv4/DHCPv6 hosts.