From the course: CCNP Routing (300-101) Cert Prep: 2 Internet Connectivity

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Filter configuration

Filter configuration - Cisco Routers Tutorial

From the course: CCNP Routing (300-101) Cert Prep: 2 Internet Connectivity

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Filter configuration

- [Instructor] Referring back to the diagram I've used for multiple examples thus far, I'll enable some simple filtering inbound and outbound on router one and two to their ISPs. I don't generally filter between iBGP peers when they are acting as border routers. My filtering configuration will be virtually identical on both peers. Only the peering addresses will be different in the neighbor statements. I'll start by configuring my inbound prefix list on router one. I P prefix list ISP to me sequence number five, deny 100.64.0.0/22 less than or equal to 32. This will deny my addressing inbound. As per BGP's function, if my ASN is in the ASpat, my own addressing should never be sent to me, but what happens if someone out on the internet spoofs my addressing, they could become best paths so I blocked that. Normally after that, I would also create deny statements for RFC 1918 carrier grate NAT, multicast and the like, but in my example those are all the ranges I'm using, so I'll let them…

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