Inter-VRF-Lite routing (1/7)
March 26, 2010 8 Comments
Customer VRFs & Global routing instance
– R1 separates Customer traffic with different routing instances “vhost4”, “vhost5” and a global routing instance for common site traffic.
– Customers (40.0.0.0/24 and 50.0.0.0/24) communicate ONLY with the common site.
Picture 1-1: topology
Inter-VRF communications depends on static routing from one VRF to other VRF outbound interfaces
ip vrf vhost4
rd 400:400
route-target export 400:400
route-target import 400:400
!
ip vrf vhost5
rd 500:500
route-target export 500:500
route-target import 500:500
R1 configuration
interface Serial1/0.104 point-to-point
ip vrf forwarding vhost4
description VRF vhost4 sub-interface
ip address 155.1.0.14 255.255.255.0
frame-relay interface-dlci 104
!
interface Serial1/0.105 point-to-point
description VRF vhost5 sub-interface
ip vrf forwarding vhost5
ip address 155.1.0.15 255.255.255.0
frame-relay interface-dlci 105
!
interface FastEthernet2/0
description Interface belonging to global routing instance
ip address 172.1.1.1 255.255.255.0
Static inter-vrf (route leaking of VRF prefixes to Global RIB)
ip route 40.0.0.0 255.255.255.0 Serial1/0.104
ip route 50.0.0.0 255.255.255.0 Serial1/0.105
VRF vhost5
ip route vrf vhost5 50.0.0.0 255.255.255.0 Serial1/0.105 155.1.0.5
static inter-vrf (route leaking of Global RIB prefixes to VRF RIB)
ip route vrf vhost5 172.1.1.7 255.255.255.255 FastEthernet2/0 172.1.1.7 global
VRF vhost4
ip route vrf vhost4 40.0.0.0 255.255.255.0 Serial1/0.104 155.1.0.4
Static inter-vrf (route leaking of Global RIB prefixes to VRF RIB)
ip route vrf vhost4 172.1.1.7 255.255.255.255 FastEthernet2/0 172.1.1.7 global
Global routing table
R1#sh ip route
Gateway of last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
C 1.1.1.1 is directly connected, Loopback1
50.0.0.0/24 is subnetted, 1 subnets
S 50.0.0.0 is directly connected, Serial1/0.105
172.1.0.0/24 is subnetted, 1 subnets
C 172.1.1.0 is directly connected, FastEthernet2/0
40.0.0.0/24 is subnetted, 1 subnets
S 40.0.0.0 is directly connected, Serial1/0.104
R1#
VRF vhost4 RIB
R1#sh ip route vrf vhost4
Routing Table: vhost4
Gateway of last resort is not set
155.1.0.0/24 is subnetted, 1 subnets
C 155.1.0.0 is directly connected, Serial1/0.104
172.1.0.0/32 is subnetted, 1 subnets
S 172.1.1.7 [1/0] via 172.1.1.7, FastEthernet2/0
40.0.0.0/24 is subnetted, 1 subnets
S 40.0.0.0 [1/0] via 155.1.0.4, Serial1/0.104
R1#
VRF vhost5 RIB
R1#sh ip route vrf vhost4
Routing Table: vhost5
Gateway of last resort is not set
50.0.0.0/24 is subnetted, 1 subnets
S 50.0.0.0 [1/0] via 155.1.0.5, Serial1/0.105
155.1.0.0/24 is subnetted, 1 subnets
C 155.1.0.0 is directly connected, Serial1/0.105
172.1.0.0/32 is subnetted, 1 subnets
S 172.1.1.7 [1/0] via 172.1.1.7, FastEthernet2/0
R1#
Testing From Customer A
vhost#trace vrf vhost5 172.1.1.7
Type escape sequence to abort.
Tracing the route to 172.1.1.7
1 50.0.0.5 88 msec 16 msec 4 msec
2 155.1.0.15 56 msec 52 msec 20 msec
3 172.1.1.7 68 msec * 124 msec
vhost#
Testing From Customer B
vhost#trace vrf vhost4 172.1.1.7
Type escape sequence to abort.
Tracing the route to 172.1.1.7
1 40.0.0.4 68 msec 20 msec 48 msec
2 155.1.0.14 52 msec 28 msec 16 msec
3 172.1.1.7 60 msec * 132 msec
vhost#
Testing from Common site
vhost#trace vrf vhost7 50.0.0.1
Type escape sequence to abort.
Tracing the route to 50.0.0.1
1 172.1.1.1 80 msec 44 msec 4 msec
2 155.1.0.5 96 msec 36 msec 16 msec
3 50.0.0.1 40 msec * 108 msec
vhost#trace vrf vhost7 40.0.0.1
Type escape sequence to abort.
Tracing the route to 40.0.0.1
1 172.1.1.1 92 msec 64 msec 4 msec
2 155.1.0.4 96 msec 48 msec 12 msec
3 40.0.0.1 64 msec * 96 msec
vhost#
About ajnouri
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Thank you for the good writeup. It if truth be told used to be a amusement account it. Look complex to far introduced agreeable from you! By the way, how can we be in contact?
Hi,
Very efficient approach
Thanks a lot
Franck
You’re welcome Franck, glad you find it useful.
Route targets are BGP extended communities, so aren’t those commands unnecessary here?
At the end, where the vrf7 come from?..
Hi Alex,
This is the first lab of the series “Inter-VRF routing”:
Notice at the end of the series introduction, I explain how I used a single router to simulate three routers vhost4, vhost5 and vhost7.
I cite myself:
“Note:
End-hosts “vhost4”, “vhost5” and “vhost7” are deployed virtually inside a single physical router with VRF-Lite locally significant (independent from VRF-Lite deployed on R1)
For more detailed information about this technique refer to the post “VRF-Lite as an alternative to VPC”
Here is a link to the post detailing the technique: