What is BGP Synchronization rules?? Can any one explain..???

Answer Posted / shahin

BGP synchronization rules states that

"Do not use or advertise to an external neighbors a route
learned by IBGP until a matching route has been learned from
IGP."

R1--------R2-------R3------R4

Here in this scenario R1 & R4 running IBP where R2 & R3
running sme IGP protocol.

As we know, for IBGP, neighbors don't need to have directly
conneted. Now when R1 tries to establish TCP session with
R4, it wud be successful to establish a session but when
updates message will come to R2 router which running IGP
(Such as OSPF/EIGRP/RIPv2) this R2 router aware of router
R4. No entry exist for path to reach R4.

As we know, router drops all the packet for unknown destination.

so all we hv to do is to sychonized the IBGP & IGP though
command. Once they synchronised with each other then only
any packet destined for R4 willbe able to pass though R2 & R3.

By default synchronization is on in all BGP running router.
Best practice to off it if all the router within the AS
running BGP.

Is This Answer Correct ?    16 Yes 2 No



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