Ok, time for some VRF lite basics and we can throw in some Dot1Q trunks to go with it.
First, let’s create our VRF called LAB
RP/0/7/CPU0:R1(config)#vrf LAB
Now we need to enable the address family for this VRF, there IPv4 Unicast
RP/0/7/CPU0:R1(config-vrf)#address-family ipv4 un
RP/0/7/CPU0:R1(config-vrf-af)#exit
Now we need to enable the IPv6 address family for this VRF
RP/0/7/CPU0:R1(config-vrf)#address-family ipv6 unicast
Now we can create our Dot1Q trunk to the other router:
RP/0/7/CPU0:R1(config-vrf-af)#int g0/3/0/3.100
Little different then IOS, but this actually makes more sense
RP/0/7/CPU0:R1(config-subif)#dot1q vlan 100
RP/0/7/CPU0:R1(config-subif)#ip add 150.1.21.1/24
RP/0/7/CPU0:R1(config-subif)#ipv6 add 2001:1:1:21::1/64
RP/0/7/CPU0:R1(config-subif)#vrf LAB

Notice that I applied the VRF LAB command after configuring the IP addresses.  If this was IOS, I would have lost all that work – but since its IOS XR, nothing takes effect until after you COMMIT the changes. 🙂
Lets look at what will be applied and then commit it.
RP/0/7/CPU0:R1(config-subif)#show config
Fri Mar 30 14:12:06.649 UTC
Building configuration…
!! IOS XR Configuration 4.1.1
vrf LAB
  address-family ipv4 unicast
  !
  address-family ipv6 unicast
  !
!
interface GigabitEthernet0/3/0/3.100
  vrf LAB
  ipv4 address 150.1.21.1 255.255.255.0
  ipv6 address 2001:1:1:21::1/64
  dot1q vlan 100
  !
end
RP/0/7/CPU0:R1(config-subif)#comm
Fri Mar 30 14:12:12.700 UTC
RP/0/7/CPU0:R1(config-subif)#
RP/0/7/CPU0:R1#
Now we should try to PING via IPv4 and IPv6 over the VRF.
Remember, when PINGing over a VRF you need to specify the VRF in the PING command.
RP/0/7/CPU0:R1#ping vrf LAB 2001:1:1:21::2
Fri Mar 30 14:17:37.291 UTC
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:1:1:21::2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 3/13/49 ms
RP/0/7/CPU0:R1#ping vrf LAB 150.1.21.2
Fri Mar 30 14:17:40.858 UTC
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 150.1.21.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 2/3/5 ms
RP/0/7/CPU0:R1#
Full connectivity, there we go!
Ok, now we can toss a routing protocol over the link – say OSPF PID 100
First though, create a loopback we can advertise over that VRF,
RP/0/7/CPU0:R1#conf t
Fri Mar 30 14:39:31.441 UTC
RP/0/7/CPU0:R1(config)#int loop1000
RP/0/7/CPU0:R1(config-if)#ip add 111.111.111.111/32
RP/0/7/CPU0:R1(config-if)#vrf LAB
Now we can configure OSPF
First, define the process identifier, here 100
RP/0/7/CPU0:R1(config-if)#router ospf 100
Now to change context to VRF LAB
RP/0/7/CPU0:R1(config-ospf)#vrf LAB
Configure our Router-ID
RP/0/7/CPU0:R1(config-ospf-vrf)#router-id 111.111.111.111
RP/0/7/CPU0:R1(config-ospf-vrf)#area 0.0.0.0
And then assign the interfaces to the area
RP/0/7/CPU0:R1(config-ospf-vrf-ar)#int loop1000
RP/0/7/CPU0:R1(config-ospf-vrf-ar)#int g0/3/0/3.100
RP/0/7/CPU0:R1(config-ospf-vrf-ar-if)#exit
RP/0/7/CPU0:R1(config-ospf-vrf-ar)#exit
Now we can check our config:
RP/0/7/CPU0:R1(config-ospf-vrf)#show configuration
Fri Mar 30 14:40:49.074 UTC
Building configuration…
!! IOS XR Configuration 4.1.1
interface Loopback1000
   vrf LAB
  ipv4 address 111.111.111.111 255.255.255.255
!
router ospf 100
  vrf LAB
    router-id 111.111.111.111
    area 0.0.0.0
      interface Loopback1000
    !
      interface GigabitEthernet0/3/0/3.100
    !
  !
 !
!
end
And finally commit the changes:
RP/0/7/CPU0:R1(config-ospf-vrf)#commit
Fri Mar 30 14:40:57.984 UTC
Now, lets check our routes:
RP/0/7/CPU0:R1#sh route vrf LAB ipv4
Fri Mar 30 14:41:40.746 UTC
Codes: C – connected, S – static, R – RIP, B – BGP
              D – EIGRP, EX – EIGRP external, O – OSPF, IA – OSPF inter area
              N1 – OSPF NSSA external type 1, N2 – OSPF NSSA external type 2
              E1 – OSPF external type 1, E2 – OSPF external type 2, E – EGP
              i – ISIS, L1 – IS-IS level-1, L2 – IS-IS level-2
              ia – IS-IS inter area, su – IS-IS summary null, * – candidate default
              U – per-user static route, o – ODR, L – local, G  – DAGR
              A – access/subscriber, (!) – FRR Backup path
Gateway of last resort is not set
L    111.111.111.111/32 is directly connected, 00:00:40, Loopback1000
C    150.1.21.0/24 is directly connected, 00:29:26, GigabitEthernet0/3/0/3.100
L    150.1.21.1/32 is directly connected, 00:29:26, GigabitEthernet0/3/0/3.100
O    222.222.222.222/32 [110/2] via 150.1.21.2, 00:00:37, GigabitEthernet0/3/0/3.100
RP/0/7/CPU0:R1#
Cool, we have a route to R2’s Loop1000 of 222.222.222.222/32.  Ping test time!
RP/0/7/CPU0:R1#ping vrf LAB 222.222.222.222 so loop1000
Fri Mar 30 14:41:50.331 UTC
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 222.222.222.222, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 2/2/4 ms
RP/0/7/CPU0:R1#
There you go, we have connectivity!