Im in the process of labbing EIGRP as the CE-PE protocol, in a standard MPLS L3 VPN setup, to further understand the BGP Cost-community attribute.
In labbing this in GNS3 the PE always seems to install the desired route via eigrp instead of via BGP in the VRF routing table. It was my understanding that the PE should install the route as a bgp route and ignore standard AD rules when referencing the bgp cost-community attribute.
Example: When the PE has #bgp bestpath cost-community ignore configured it prefers it locally generated bgp route (As expected) over the MP-BGP route. Route learned via backdoor link is installed as an EIGRP route.
PE
R5#show ip route vrf V_1 | i 100.100
D 100.100.100.100
R5#show bgp vpnv4 unicast all 100.100.100.100
11.11.25.2 from 0.0.0.0 (5.5.5.5)
Origin incomplete, metric 528000, localpref 100, weight 32768, valid, sourced, best
Configure no bgp bestpath cost-community ignore on PE and the MP-BGP learned route with lower community cost than backdoor link cost is the best bgp route as desired:
config t
router bgp 100
no bgp bestpath cost-community ignore
R5#show bgp vpnv4 unicast all 100.100.100.100
Local, imported path from 100:10:100.100.100.100/32 (global)
9.9.9.9 (metric 3) from 6.6.6.6 (6.6.6.6)
Origin incomplete, metric 10880, localpref 100, valid, internal, best
The Vrf table is showing the bgp routes marked with a rib failure as if eigrp routes are considered best and the routing table still reflects this.
r 100.100.100.100/32 11.11.25.2 528000 32768 ?
r>i 9.9.9.9 10880 100 0 ?
In reading the reference article it states:
"EIGRP selects the best path based on shortest EIGRP metric and install it into the VRF routing table. If the best path was learned from BGP, the route is installed as BGP route, not as an EIGRP one"
I jacked up the delay on one of the backdoor transit links (outside of making the metric infinite) and the PE still installs the route as eigrp instead of bgp.
Is this a potential bug, gns3 issue, etc or am I misunderstanding something?
http://blog.ine.com/wp-content/uploads/2010/04/understanding-eigrp-soo-bgp-cost-community.pdf
