OSPF - ASBR E-bit in an LSA
Within the context of an OSPF topology, the E-bit, also called the ASBR bit, is a flag found within a Type 1 LSA that indicates that the sending router is an ASBR. It is used to signal to its neighbors that it is capable of reaching networks that are external to the OSPF domain.
When an ASBR sends such a Type 1 LSA< the receiving ABR will relay that information to the rest of the OSPF domain as a Type 4 Summary LSA, as shown in the following diagram:
Links:
https://forum.networklessons.com/t/ospf-lsa-types-explained/1127/201?u=lagapidis