On Sat, 20 Apr 2024 at 10:00, Mark Tinka <mark@tinka.africa> wrote:
This would only matter on ultra long haul optical spans where the signal would need to be regenerated, where - among many other values - FEC would need to be decoded, corrected and re-applied.
In most cases, modern optical long haul has a transponder, which terminates your FEC, because clients offer gray, and you like something a bit less depressing, like 1570.42nm. This is not just FEC terminating, but also to a degree autonego terminating, like RFI signal would be between you and transponder, so these connections can be, and regularly are, provided without proper end-to-end hardware liveliness, and even if they were delivered and tested to have proper end-to-end HW liveliness, that may change during operation, so line faults may or may not be propagated to both ends as RFI assertion, and even if they are, how delayed they are, they may suffer delay to allow for optical protection to engage, which may be undesirable, as it eats into your convergence budget. Of course the higher we go in the abstraction, the less likely you are to get things like HW livelines detection, like I don't really see anyone asking for this in their pseudowire services, even though it's something that actually can be delivered. In Junos it's a single config stanza in interface, to assert RFI to client port, if pseudowire goes down in the operator network. -- ++ytti