Communication of VLans of two different sites

[girish_p1]

My company has two sites e.g in Hanoi and Salo. In both sites I have created VLans in my core switches. How can I enable communication between the VLans of both the sites over MPLS. 

[Jon Marshall · Accepted solution]

It's not clear what you are asking ie. do you already have MPLS setup at each site or not ?

At a very high level you simply need each site to advertise it's subnets to the MPLS network but you don't say exactly what the issue is.

Jon

[girish_p1]

Hi Jon, 

Thanks for your response. Actually MPLS is already setup but I wanted to know about the concept of Transit VLans so when I asked this to my senior then he asked me the above question in reply that how to can we make this happen and once we are able to do so then I will understand the concept of transit VLANs. :-D

Can you help me now.. Thanks in advance

[Jon Marshall]

Still not sure :)

If you mean have the same vlan at both sites then it depends on your MPLS setup ie. is it L2 or L3 ? A L3 MPLS setup is the more common and then you would have to use some specific protocol to extend that vlan. What you can use  depends on the hardware you have,.

Is that what you mean by transit vlan and if so do you really need it or could you just route between sites.

If you mean something else please clarify.

Jon

[Julio E. Moisa]

Hi

If you are using any routing protocol on the Core switches to distribute the prefixes through the MPLS VPNs  you could include these new subnets on that routing protocol on the CE devices, I am assuming they are the core switches. 

For example

CE1 ---> PE1 ---> MPLS  ----> PE2  ----> CE2

CE is handled by the client

So you should just configure the new subnets under the routing protocol process, I used OSPF but it can be, RIP, Eigrp, etc or you could use static route.

CE1
conf t
router ospf 1
network 10.12.0.1 0.0.0.0 area 0
network <your new networks> <wildcard> area 0    ---> it will advertise the new subnets to the PE 

interface g0/0
ip add 10.12.0.1 255.255.255.0
no shut

*No special configurations.

PE is handled by the Provider.

PE1 should have a configuration like:

ip vrf A
rd 1:1
route-target export 1:1
route-target import 1:1

interface g0/0
ip vrf forward A
Ip add 10.12.0.2 255.255.255.0

router ospf 1 vrf A
network 10.12.0.2 0.0.0.0 area 0
redistribute bgp 100 subnets

router bgp 100
address-family ipv4 vrf A
redistribute ospf 1

Note, there is a mutual redistribution on the PE, it is because PE is going to advertise the subnets from the CE to the other PE and finally it will be known on the CE2 and the PE2 will advertise the subnets from CE2 known via OSPF to PE1 and PE1 will advertise the subnets to CE1 through the routing protocol in this case OSPF. 

And it is the same for the other side, This is an example and Im omitting all the MPLS configuration but basically it is the idea. I you have the same networks on both Core switches you could use differents VRF for each other. 

Hope it is useful

:-)