Fastpath and Slowpath Packet Captures
The packet capture in MonSub takes place in Slowpath and Fastpath.
Slowpath
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Slowpath PCAP captures the packets going through slowpath (application).
When option PFCP(49), GTPU(26), L3(19), and CSS(34) is enabled, N4 messages/data packets are shown from the time MonSub is enabled.
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Uplink data packet is shown as incoming GTPU, rulematch, outgoing L3.
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Downlink data packet is shown as incoming L3, rulematch, outgoing L3.
Fastpath
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Fastpath PCAP will capture the packets going through fastpath.
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For pure Fastpath packets, the uplink data packet is shown as incoming GTPU, outgoing L3.
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Downlink data packet is shown as incoming L3, outgoing GTPU.
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Slowpath packets are also shown in Fastpath PCAP, while egressing the UPF in both directions.