Reference manual for squid's configuraiton directives
| Index | Alphabetical Index |
happy_eyeballs_connect_timeout
This Happy Eyeballs (RFC 8305) tuning directive specifies the minimum
delay between opening a primary to-server connection and opening a
spare to-server connection for the same master transaction. This delay
is similar to the Connection Attempt Delay in RFC 8305, but it is only
applied to the first spare connection attempt. Subsequent spare
connection attempts use happy_eyeballs_connect_gap, and primary
connection attempts are not artificially delayed at all.
Terminology: The "primary" and "spare" designations are determined by
the order of DNS answers received by Squid: If Squid DNS AAAA query
was answered first, then primary connections are connections to IPv6
peer addresses (while spare connections use IPv4 addresses).
Similarly, if Squid DNS A query was answered first, then primary
connections are connections to IPv4 peer addresses (while spare
connections use IPv6 addresses).
Shorter happy_eyeballs_connect_timeout values reduce master
transaction response time, potentially improving user-perceived
response times (i.e., making user eyeballs happier). Longer delays
reduce both concurrent connection level and server bombardment with
connection requests, potentially improving overall Squid performance
and reducing the chance of being blocked by servers for opening too
many unused connections.
RFC 8305 prohibits happy_eyeballs_connect_timeout values smaller than
10 (milliseconds) to "avoid congestion collapse in the presence of
high packet-loss rates".
The following Happy Eyeballs directives place additional connection
opening restrictions: happy_eyeballs_connect_gap and
happy_eyeballs_connect_limit.
| Index | Alphabetical Index |