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 is locally significant and only the configured router knows the weight, it is only viable … Continue reading BGP attributes: Weight

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 Up/Down State/PfxRcd 192.168.12.1 4 1 44 43 1 0 0 00:36:08 0 R2 did not … Continue reading IP routing with BGP

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 a BGP router. However this step can be simplified by peering the BGP speaker's loopback … Continue reading BGP: Injecting IGP route into BGP without redistribution

BGP: Load balancing using ebgp multihop and loopback interface.

1841-1 configuration 1841-1#sh run | s router bgp router bgp 64512 no synchronization bgp log-neighbor-changes network 172.16.1.0 mask 255.255.255.0 neighbor 110.1.1.1 remote-as 64513 neighbor 110.1.1.1 ebgp-multihop 2 neighbor 110.1.1.1 update-source Loopback64512 no auto-summary 1841-1#sh run | i ip route ip route 110.1.1.1 255.255.255.255 192.168.1.2 ip route 110.1.1.1 255.255.255.255 192.168.2.2 1841-2 Configuration 1841-2#sh run | s … Continue reading BGP: Load balancing using ebgp multihop and loopback interface.

Tshoot BGP: Path unchanged despite local preference has been modified.

All routers within their own AS has been configured with IGP, routers within their own AS are reachable to one another (imagine the above diagram is part of an AS network). The border routers are connected to each other AS and exchanging prefixes. As shown in the diagram, two paths have different bandwidth, suboptimal routing … Continue reading Tshoot BGP: Path unchanged despite local preference has been modified.