In order to use applications over IPv6, it is necessary that usersĮnjoy nearly identical performance as compared to IPv4. RFC 6555 Happy Eyeballs Dual Stack April 2012ġ. The Trust Legal Provisions and are provided without warranty as Include Simplified BSD License text as described in Section 4.e of Code Components extracted from this document must Please review these documentsĬarefully, as they describe your rights and restrictions with respect This document is subject to BCP 78 and the IETF Trust's Legal Information about the current status of this document, any errata,Īnd how to provide feedback on it may be obtained atĬopyright (c) 2012 IETF Trust and the persons identified as the Internet Standards is available in Section 2 of RFC 5741. Internet Engineering Steering Group (IESG). Received public review and has been approved for publication by the It represents the consensus of the IETF community. This document is a product of the Internet Engineering Task Force This is an Internet Standards Track document. Specifies requirements for algorithms that reduce this user-visible Stack client to have a worse user experience. This is undesirable because it causes the dual. IPv6 path and protocol are not working, a dual-stack clientĪpplication experiences significant connection delay compared to an When a server's IPv4 path and protocol are working, but the server's Happy Eyeballs: Success with Dual-Stack Hosts Internet Engineering Task Force (IETF) D. This is undesirable because it causes the. When a server's IPv4 path and protocol are working, but the server's IPv6 path and protocol are not working, a dual-stack client application experiences significant connection delay compared to an IPv4-only client. Retries under the new version are also now limited per-address where in the older versions each retry meant a full DNS result set of addresses was re-tried.Īs a result dns_timout is separated from connect_timeout which is now fully controlling only one individual TCP connection handshake.Happy Eyeballs: Success with Dual-Stack Hosts Autor(en): A. TCP connection attempts are still run in serial, but where older versions of Squid interspersed a DNS lookup with each set of TCP attempts the new 3.2 code identifies all the possible destinations first and tries each individual address until a working connection is found. As a result the maximum DNS lookup time is reduced from the sum of A and AAAA response times, to the maximum of both. Although Firefox implementation of the “Happy Eyeballs” algorithm appears to have been instrumental in uncovering a certain major bug in Squids new connection handling recently.įor those interested, Squid-3.2 does implement by default a variation of the “Happy Eyeballs” algorithm.ĭNS lookups are performed in parallel now, as opposed to serial as they were in 3.1. Squid operating as forward proxy do not face this issue as each browser only opens a limited number of connections to the proxy. Whether or not you are operating an existing interception proxy or installing a new one this is one major new feature of the modern web which needs to be taken into account when provisioning the network and Squid socket/FD resources. Geoff Huston wrote up a very interesting analysis of the RFC 6555 “Happy Eyeballs” features being added to web browsers recently.Īs these features reach the mainstream stable browser releases and more people being using them Squid in the role of intercepting proxy are starting to face the same issues mentioned for CGN gateways.
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