Category Archives: BGP

BGP

BGP attributes: Weight

Facts about BGP weight attribute Cisco proprietary. Only available for Cisco routers, this attribute is not included in BGP update message. Because it is not included in update message, this attribute is only locally significant to one router. Because it … Continue reading

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IP routing with BGP

Problem 1: Did not receive prefix advertised by BGP peer. R2#sh ip bgp summary BGP router identifier 2.2.2.2, local AS number 2 BGP table version is 1, main routing table version 1 Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ … Continue reading

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BGP: Route reflector

Split horizon Split horizon rule is to prevent routing loop. In iBGP a router which learns prefixes from a BGP speaker will not advertise to BGP speaker, this makes a full mesh iBGP peering necessary in order for other BGP … Continue reading

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MPLS Layer 3 VPN

Acknowledgement Without MR.Keith Barker’s 21 minutes video instruction, constructing MPLS VPN lab will take a longer time. His 21 minutes video instruction summarizes all. MR. Keith Barker has amazing skills to translate complicated concepts into simpler and easier to understand … Continue reading

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BGP: Injecting IGP route into BGP without redistribution

The diagram is complicated with an additional link, and instead of full BGP route in AS65000, the BGP route is propagated with the help of OSPF. In previous lab, the BGP full mesh was established by peering both subnets of … Continue reading

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BGP: Route filter with ip prefix-list

Using the same network diagram, I would want prefix 10.20.0.0 to be filtered from advertisement by the border iBGP routers (r1 and r3). Using prefix-list is a more granular method than using ACL with distribute-list. Hide r2 prefixes from r5 … Continue reading

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BGP: Full mesh BGP without IGP

r1, r2 and r3 have full meshed BGP peering. No IGP was used. BGP synchronization Before a BGP route is advertised and added to the routing table, this route must be known via an IGP. For the case of AS65000, … Continue reading

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