|
|
|
In order to provide sufficient measurements to both CNA systems, your DNS implementation should rotate single pixel GIF requests through all available USTATs on both devices, not just those on one device. This will halve the rate of measurements reaching either of the CNA systems and it will mean that each of the two CNA systems will have a slightly different database of measurements, but over time they should average out to the same measurement profile.
It will be possible for one of the two CNA systems to have insufficient measurements for a prefix that is adequately measured on the other device. The worst that can happen if one device falls out is that traffic will fall back to BGP for that prefix until the device acquires a sufficient number of measurements.
There may also be rare instances when each of the two CNA systems has asserted a different link for a prefix, but this should be a temporary, and self-correcting, condition as the two measurement databases grow. And, since routes are weighted in favor of the primary CNA system, only one route assertion will be accepted by the router.
|
|
|