-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Joe Abley wrote: > This suggests to me that for large, anycast-distributed servers there is > an opportunity for unbound to give up to early whenever services are > moved between far-distant anycast nodes. > > What is the actual algorithm?
Exponential backoff. (I think internet software should do exponential backoff because that is good behaviour.) > For example, if the RTT to an anycast server suddenly changes from > reliably <20ms to something substantially higher, what is the threshold > RTT at which we can expect unbound to stop being able to get answers? If it becomes more than 16x or 32x slower, then you can expect a first servfail as lots of exponential backoff probes are failing. And then things work again. If there is some other server in the NS set that does not move like this, then the (1 second of) servfail does not happen. In that case, unbound finds out the new rtt for the moved server gradually, using the other server if the slow server does not respond quickly enough. Best regards, Wouter -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org iEYEARECAAYFAkopKHQACgkQkDLqNwOhpPinyACdGvfUZcOyZDMF5zUBtWRHtZNd yooAmQGTvjkpex2oQsefdOtmjBq/mA9g =RRyl -----END PGP SIGNATURE----- _______________________________________________ Unbound-users mailing list [email protected] http://unbound.nlnetlabs.nl/mailman/listinfo/unbound-users
