问题：

[多选] Which two statements are true about IBGP neighbor relationships?（）

A . The BGP split - horizon rule specifies that routes learned via EBGP are never propagated to other IBGP peers.
B . The BGP split horizon rule specifies that routes learned via IBGP are never propagated to other IBGP peers.
C . A full - mesh IBGP requires that neighbor relationships be established between a ll BGP enabled routers in the autonomous system.
D . IBGP neighbors must be in different autonomous systems.
E . An EGP or static routing is required between IBGP neighbors.