I am unable to understand how non connected IBGP peer send update to each other without redistributing BGP into IGP
Lets take an Eg
R1------> R2------------->R3----------> R4
you must have seen this scenario in case of BGP synchronization
Now R1 and R2 are connected via EBGP , R2 and R4 are connected via IBGP and we have ospf running on R2 , R3 and R4 but BGP and OSPF are not redistributed. Here synchronization is On, Now R1 will send an update about 10.10.10.0/24 to R2 ,I have seen in many cisco docs that R2 will send this update to R4 . My Question is since we are not having any redistribution between IGP and BGP so how did the update reached R4
Let's say it is send via R3 so would R3 make changes into its own routing table for this new route for 10.10.10.0/24 if not Why?
Now Let say R2 sends that update via R3 but R3 didn't make changes into it's routing table . Now R4 have received a data with destination to 10.10.10.0/24 now R3 didn't have route to 10.10.10.0/24 into it's IGP so it would drop this packet . My question is can't this data be send via the same process through which R4 receive the update from R2 via R3
Thanks in advance