New TCP-based fields available in Rulesets

Build rules based on TCP transport and latency

Cloudflare now provides two new request fields in the Ruleset engine that let you make decisions based on whether a request used TCP and the measured TCP round-trip time between the client and Cloudflare. These fields help you understand protocol usage across your traffic and build policies that respond to network performance. For example, you can distinguish TCP from QUIC traffic or route high latency requests to alternative origins when needed.

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New fields

Field	Type	Description
cf.edge.client_tcp	Boolean	Indicates whether the request used TCP. A value of true means the client connected using TCP instead of QUIC.
cf.timings.client_tcp_rtt_msec	Number	Reports the smoothed TCP round-trip time between the client and Cloudflare in milliseconds. For example, a value of 20 indicates roughly twenty milliseconds of RTT.

Example filter expression:

cf.edge.client_tcp && cf.timings.client_tcp_rtt_msec < 100

More information can be found in the Rules language fields reference.