The severity of the condition on the link when the
notification is sent. A smaller enumerated integer value
indicates that the exceeded condition is more severe.
When a red severity notification is sent, it signifies
that a severe event has occured, in which certain errors
over an interval have reached/exceeded a high threshold .
When a yellow severity notification is sent it signifies
that an event has occured, in which certain errors over
an interval have reached/exceeded a low threshold.