VRF Questions

[icecream-guy]

so I'm looking over

http://www.netcraftsmen.com/using-bgp-with-vrf-lite-for-shared-service-support/

topic about shared services in a vrf configuration,

the PE-S shared services router has

Code Select Expand


ip vrf Blue
rd 88:2
!
ip vrf Red
rd 26:4
!
ip vrf Shared
rd 16:16


but when they get into the part where they import/export the traffic to the shared VRF,

they have

Code Select Expand


PE-S(config)#ip vrf Shared
PE-S(config-vrf)# rd 16:16
PE-S(config-vrf)# route-target export 30:30
PE-S(config-vrf)#route-target import 10:10
PE-S(config-vrf)#route-target import 20:20
PE-S(config-vrf)#
PE-S(config-vrf)#ip vrf Blue
PE-S(config-vrf)# rd 88:2
PE-S(config-vrf)# route-target export 20:20
PE-S(config-vrf)#route-target import 30:30
PE-S(config-vrf)#
PE-S(config-vrf)#ip vrf Red
PE-S(config-vrf)# rd 26:4
PE-S(config-vrf)# route-target export 10:10
PE-S(config-vrf)#route-target import 30:30
PE-S(config-vrf)#


I don't know where they are coming up with these route targets, I think they should be using 88:2 and 26:4 as the rd targets.
I don't knwo where they are coming up with the 10:10 and 20:20  are these just arbitrary numbers,  not sure how this is working.
are these arbitrary numbers local to the PE-S router ? but I can't see how the shared PS-S router is importing the blue and red vrf routes.
I understand the 30:30 rout target for the shared for exports, that's just an arbitrary number and I do see how that route-target is exported from the shared vrf and imported into the others

can one of you vrf experts have a look at that link end explain the use of the 10:10 and 20:20 route targets?

or are they arbitrary so that the red and blue vrfs cant import due to the use of different route targets?

[Dieselboy]

I've never used import/export VRF routes.

When we've set up the "RD" route distinguisher, we've used the loopback ip as an I.D. followed by the VRF number of the customer. For example:
ip vrf Blue
rd 172.16.1.1:10

We did eventually route between VRFs but only for our management and it was routed through an ASA.

Sorry this is not much help whatsoever but hopefully it's another piece of the puzzle (information sharing). I would also like to understand and see a working import / export routes example.

[wintermute000]

RT only deals with other RD. There is actually no technical linkage between the two.

RT IS passed along in BGP attributes. That's how MPLS-VPN works. RD is totally locally significant but RT is shared.

I agree at first glance VRF blue and red are missing the import for their own exports. However this may not matter if the router is purely doing shared services. I see you're looking @ http://www.netcraftsmen.com/using-bgp-with-vrf-lite-for-shared-service-support/

I think the bit they don't explain well is: the shared services router doesn't have to export any native VRF blue or VRF red routes because its not connecting anything from VRF blue or red. Its only purpose is to send the two PEs routers the shared services routes with RT 30, and to get RT 20/10 into the shared services VRF ON THAT ROUTER ONLY (coz you don't want to leak between the customers on any other PEs!).
The other bit they're horrible for not explaining is the full RT/RD config on PE1/2: yes, VRF blue would simply be import/export 20:20.
PE-S is the one doing the lifting, its importing RD 30:30 and sending it back to the other PEs.

See this primer, good clear example where the shared RT is in addition to importing/exporting yourself
http://packetlife.net/blog/2013/jun/10/route-distinguishers-and-route-targets/

Wait till you deal with shadow route reflectors / diverse path and other wonderful tricks from the era before BGP add-path.....

[icecream-guy]

See this primer, good clear example where the shared RT is in addition to importing/exporting yourself
http://packetlife.net/blog/2013/jun/10/route-distinguishers-and-route-targets/

Wait till you deal with shadow route reflectors / diverse path and other wonderful tricks from the era before BGP add-path.....

yeah, I was reading Jeremy's site last night. helped much.

p.s thanks for the clarification