Perform similar steps between ESR3 and CE_SiteB routers.
Configure the corresponding interfaces and create eBGP session between ESR3 and CE_SiteB:
CE-SiteB(config)# interface gigabitethernet 1/0/2
CE-SiteB(config-if-gi)# ip firewall disable
CE-SiteB(config-if-gi)# ip address 192.168.32.6/30
CE-SiteB(config-if-gi)# exit
CE-SiteB(config)#
CE-SiteB(config)# interface loopback 1
CE-SiteB(config-loopback)# ip address 10.100.1.1/24
CE-SiteB(config-loopback)# exit
CE-SiteB(config)#
CE-SiteB(config)# route-map OUTPUT
CE-SiteB(config-route-map)# rule 1
CE-SiteB(config-route-map-rule)# match ip address 10.100.1.0/24
CE-SiteB(config-route-map-rule)# action permit
CE-SiteB(config-route-map-rule)# exit
CE-SiteB(config-route-map)# exit
CE-SiteB(config)#
CE-SiteB(config)# router bgp 65505
CE-SiteB(config-bgp)# router-id 192.168.32.6
CE-SiteB(config-bgp)# neighbor 192.168.32.5
CE-SiteB(config-bgp-neighbor)# remote-as 65500
CE-SiteB(config-bgp-neighbor)# allow-local-as 1
CE-SiteB(config-bgp-neighbor)# update-source 192.168.32.6
CE-SiteB(config-bgp-neighbor)# address-family ipv4 unicast
CE-SiteB(config-bgp-neighbor-af)# route-map OUTPUT out
CE-SiteB(config-bgp-neighbor-af)# enable
CE-SiteB(config-bgp-neighbor-af)# exit
CE-SiteB(config-bgp-neighbor)# enable
CE-SiteB(config-bgp-neighbor)# exit
CE-SiteB(config-bgp)# address-family ipv4 unicast
CE-SiteB(config-bgp-af)# network 10.100.1.0/24
CE-SiteB(config-bgp-af)# exit
CE-SiteB(config-bgp)# enable
CE-SiteB(config-bgp)# exit
CE-SiteB(config)# do commit
CE-SiteB(config)# do confirm
Configure eBGP for ESR3 and allow transmission of routing information from VRF ro VPNv4 table: