Sync rule says that BGP transit as will never send the route from 1 as to another as untill unless it is learned via IGP, but I have the same routes installed in the IGP table through redistribution, but still my transit AS is not sending the traffic to adjecent AS if I enable sync., why is it so..
Thanks in advance
The synchronization might be an issue if you use ospf as your IGP and you also use route-reflectors. The reason is that with ospf as an IGP, the BGP synchronization check doesn't only verify that the route as been learnt via the IGP but also that the advertising router for that ospf route is equal to the BGP peer RID, which will not be the case if you use route-reflectors.
In this case the only solution is to disable the synchronization, which should be turned off by default anyway.