Industry standard for EBGP is described in RFC8212, which can be found on the URL shown on the screen. This RFC basically describes EBGP route propagation behavior without policies. Please note that BGP in Cisco IOS is permissive by default, which is contrary to industry standard and RFC8212. When configuring BGP peering without using filters, this means that all best paths on the local router are passed to the neighbor. All routes announced by the neighbor are received by the local router as well. This can have disastrous consequences such as route leaks, which means traffic being routed through an unexpected path. You can look at RFC8212 for more information. So what are the EBGP configuration best practices? EBGP best practice is to ensure that each eBGP neighbor has an inbound and an outbound filter applied. If you look at the example on the screen, router with ASN of 64511 has an eBGP neighbor with IPv4 address of 100.64.0.1 with an ASN of 64510. As you can see it has a filter named "as64510-in" applied to its inbound prefix, and another named "as64510-out" applied to its outbound prefixes.

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