How it Works
This section describes how IP Threshold SMF and IPAM Integration works.
Intimation of a threshold hit condition from IPAM to SMF: When IP addresses in a DNN for a UPF left with a “threshold” configured number of IP addresses in a IPAM module gives information to SMF using resource management response.
SMF behaviour when a threshold hit received: SMF marks a usable threshold hit for a given UPF. Since IPAM pool distribution is per node manager separately, SMF marks a threshold separately for primary and secondary node manager.
SMF behaviour choosing UPF for new session when a threshold marked: SMF performs the following checks.
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If a threshold hit for a primary node manager and secondary node manager is not hit, IP allocation request is sent for a secondary node manager.
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If a threshold hits both primary and secondary node manager, then current UPF selects the lower priority node manager, if any other UPF configured and threshold not hit is selected first.
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If all the UPFs are threshold hit, then the behaviour falls back to priority and load based which is existing behaviour. This is similar to that of a non-existence threshold hit behaviour.
Important | Refer IP Address Management chapter for configuration details. |
Recovery behaviour from a threshold hit: IPAM to periodically if UPF has come out of threshold hit condition. When UPF has enough free addresses to come out of threshold hit (for each DNN, and each UPF) IPAM gives information of SMF (through a callback). SMF unmarks UPF as threshold hit.
When IP addresses in a pool (for each DNN, and each UPF) left with a “threshold” configured number of IP addresses in a IPAM module gives information to SMF using resource management response.