ip vrf vrf00001
rd 888:1
route-target both 888:1
ip vrf vrf00002
rd 888:2
route-target both 888:2
route-target import 888:1
import map vrf00002-import-map
route-map vrf00002-import-map permit 10
match ...
It is important to note that the route map is only needed for fine tuning. Normal import/export with VRFs can just extended communities. The thought of security depending on getting route maps built right rather scares me. Luckily, basic security is provided at the extended community level, making route hiding the normal situation. Then route maps can be used to limit connectivity to extranet partner sites, if the customers don't wish to do that for themselves by speaking BGP to the PE routers.
These VRFs would typically then be associated with interfaces:
interface Fastethernet 0/2
ip vrf forwarding vrf00001
ip address ...
interface Fastethernet 0/3
ip vrf forwarding vrf00002
ip address ...
interface Fastethernet 0/4
ip vrf forwarding vrf00002
ip address ...
VRF vrf00002 is associated with two interfaces that connect to two sites for Customer B. I'm deliberately showing FastEthernet, since some people now think that's how we'll be connecting to SPs in metropolitan settings. (Think BLEC: Building Local Exchange Carrier, providing VPN, Internet, and Voice connectivity).
We need to be speaking MBGP to carry VPN-IPv4 routes and attributes to peer PE routers. We don't need ordinary BGP routes to PE peers however. (On a larger scale, we might use route reflectors vice iMBGP full-mesh peering):
router bgp 888
no synchronization ! don't do IGP synchronization (since
! the IGP won't carry the right routes anyway)
no bgp default ipv4-activate ! don't do ordinary BGP
neighbor 10.60.0.5 remote-as 888 ! identify an iBGP neighbor and AS
neighbor 10.61.0.1 remote-as 888 ! identify another
address-family vpnv4 unicast
neighbor 10.60.0.5 activate ! activate session to some MBGP peer
neighbor 10.61.0.1 activate ! some other MBGP peer
exit-address-family
Our design might use eBGP to communicate routes to CE routers in a controlled way, to get routes into each VRF. Or it might use static routing, or some other mix. We can also define per-VRF static routes as shown below.
address-family ipv4 unicast vrf vrf00001
redistribute static
redistribute connected
neighbor 10.20.1.1 remote-as 65535 ! private AS number
neighbor 10.20.1.1 activate
no auto-summary
exit-address-family
address-family ipv4 unicast vrf vrf00002
redistribute static
redistribute connected
neighbor 10.20.2.2 remote-as 65535
neighbor 10.20.2.2 activate
no auto-summary
exit-address-family
ip route vrf vrf00001 15.0.0.0 255.0.0.0 e0/2 10.20.1.1
