Blog Posts in May 2025
OSPF Loop Prevention with Area Range Summary LSAs
In a previous blog post, I described how OSPF route selection rules prevent a summary LSA from being inserted back into an area from which it was generated. That works nicely for area prefixes turned directly into summary LSAs, but how does the loop prevention logic work for summarized prefixes (what OSPF calls area ranges)?
TL&DR: It doesn’t, unless… ;)