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Variables
Backend connection
backend.conn.is_tls
backend.conn.tls_protocol
backend.socket.congestion_algorithm
backend.socket.cwnd
backend.socket.tcpi_advmss
backend.socket.tcpi_bytes_acked
backend.socket.tcpi_bytes_received
backend.socket.tcpi_data_segs_in
backend.socket.tcpi_data_segs_out
backend.socket.tcpi_delivery_rate
backend.socket.tcpi_delta_retrans
backend.socket.tcpi_last_data_sent
backend.socket.tcpi_max_pacing_rate
backend.socket.tcpi_min_rtt
backend.socket.tcpi_notsent_bytes
backend.socket.tcpi_pacing_rate
backend.socket.tcpi_pmtu
backend.socket.tcpi_rcv_mss
backend.socket.tcpi_rcv_rtt
backend.socket.tcpi_rcv_space
backend.socket.tcpi_rcv_ssthresh
backend.socket.tcpi_reordering
backend.socket.tcpi_rtt
backend.socket.tcpi_rttvar
backend.socket.tcpi_segs_in
backend.socket.tcpi_segs_out
backend.socket.tcpi_snd_cwnd
backend.socket.tcpi_snd_mss
backend.socket.tcpi_snd_ssthresh
backend.socket.tcpi_total_retrans
backend.{NAME}.connections_open
backend.{NAME}.connections_used
backend.{NAME}.healthy
bereq.between_bytes_timeout
bereq.connect_timeout
bereq.first_byte_timeout
beresp.backend.alternate_ips
beresp.backend.ip
beresp.backend.port
beresp.backend.requests
beresp.backend.src_ip
beresp.handshake_time_to_origin_ms
beresp.used_alternate_path_to_origin
ratecounter.{NAME}.bucket.10s
ratecounter.{NAME}.bucket.20s
ratecounter.{NAME}.bucket.30s
ratecounter.{NAME}.bucket.40s
ratecounter.{NAME}.bucket.50s
ratecounter.{NAME}.bucket.60s
ratecounter.{NAME}.rate.10s
ratecounter.{NAME}.rate.1s
ratecounter.{NAME}.rate.60s
req.backend
req.backend.healthy
req.backend.is_cluster
req.backend.is_origin
req.backend.is_shield
Backend request
Backend response
Cache object
Client connection
Client request
Client response
Date and time
ESI
Geolocation
Math constants limits
Miscellaneous
Segmented caching
Server
fastly.toml
Home
Reference documentation
VCL Reference
Variables
Backend connection
backend.socket.tcpi_total_retrans
INTEGER
, read-only.
Available in
fetch
Number of TCP retransmissions for the backend connection.
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