From the course: Cisco CCNP ENARSI v1.1 (300-410) Cert Prep: 2 VPN Technologies

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BGP synchronization

BGP synchronization

From the course: Cisco CCNP ENARSI v1.1 (300-410) Cert Prep: 2 VPN Technologies

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BGP synchronization

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- BGP synchronization is not used very commonly today, but there may still be rare cases where this feature is needed. There also maybe older devices that you run across, which have that enabled. By default in newer versions of Cisco iOS, the synchronization rule is already disabled, but if you're running an older version, you would need to disable that in many cases. The synchronization rule is a way to avoid what we refer to as a traffic black hole, where traffic would be inadvertently dropped in an undesired manner. BGP synchronization will only advertise a route learned from an iBGP peer to an eBGP peer. when there is an exact match of that route learned from an IGP in the routing table. That's the synchronization rule. Let's look at this in a lab environment. This is our topology, we have three routers. You can see that R1 is in AS 65,100 while R2 and R3 are in AS 65,200. We're going to go in and explicitly configure the no synchronization rule and also configure our BGP…

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