5G • Core Network
UL CL
Uplink Classifier
UPF functionality that inspects uplink packet destination IPs and diverts matching flows locally to edge servers.
Technical Explanation
An Uplink Classifier (UL CL) is a UPF feature operating on IPv4 sessions. Controlled by SMF over N4, it inspects uplink packet headers: traffic destined for local edge servers is diverted directly to a local data network, while all other general Internet traffic continues over N9 to the central anchor PSA.
Key Functions
- Inspects uplink packet headers to divert traffic matching packet filters
- Routes edge traffic locally while forwarding standard traffic to central core
- Transparent to the UE: requires zero client software modification
Specifications
3GPP TS 23.501
Interfaces
N4N6N9
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