The following network diagram depicts a scenario where a 10Gbps link connects the routers R2 and R4 and a40Gbps link connects the routers R3 and R5:Figure 36. Sample BGP Link Bandwidth ConfigurationIn this scenario, there is an additional 40Gbps link that is sometimes activated between the routers R2 and R5.When LB is configured on the routers R2 and R3 to communicate with their EBGP peers (routers R4 and R5respectively), router R2 advertises path X to router R1 with LB indicating that a 10Gbps link is available forcommunication. Also, the router R3 advertises the path X with LB indicating that a 40Gbps link is available(converted to bytes per second).If all the required Multipath criteria is satisfied, the router R1 selects both the paths as part of the BGP routeselection and installs these paths in the RIB along with the relative weights of the paths. This mechanismresults in load sharing of traffic corresponding to path X across both the available paths in a 4:1 ratio.The following example shows the configuration in each router shown in Figure 1:R1#interface vlan 10ip address 1.1.1.1/24no shutrouter bgp 1maximum-paths ibgp 2bgp dmzlink-bwneighbor 1.1.1.2 remote-as 1neighbor 1.1.1.2 no shutdownneighbor 1.1.1.3 remote-as 1neighbor 1.1.1.3 no shutdownR2#interface tengigbitethernet 1/1ip address 1.1.1.2/24no shutinterface tengigbitethernet 1/2ip address 4.4.4.1/24no shutinterface fortyGigE 1/48ip address 5.5.5.1/24no shutrouter bgp 1maximum-paths ebgp 2bgp dmzlink-bwneighbor 1.1.1.1 remote-as 1Equal Cost Multi-Path (ECMP) 417
