L2VPN and L3VPN Question

Hi all,

In the ISP I am working:

Q1)I realized that the L2VPN has QinQ termination at the service provider edge. However, the L3VPN goes to a logical router (VRF) without QinQ termination. Why is it like this?

Q2) Why are all the customers using the same L3VPN_VRF?? I dont understand the concept. If they are connected on the same logical router, wouldnt different customers be able to ping each other?

Just to add that the L3 routes are advertised as static routes in the VRF. Perhaps this will help.

Q3) My ISP also uses a different naming convention for RD and RT. For RD, the naming convention is ip add:nn; however, for RT the naming convention is ASN:nn. Is there a reason for this? I am reading MPLS fundamentals and the RD and RT are both the same.

Q4) Can MPLS and VPLS be run at the same time?

Pardon me for the questions. Thanks!

Find more posts tagged with

Comments

DCD

What has your research turn up? What book are you using?

networker050184

Both of those just depend on the set up. Would need more information to give you anything helpful really.

hitmen

DCD wrote: »

What has your research turn up? What book are you using?

Perhaps you can give me a hint? I am using MPLS fundamentals.

For Q1) For L2vpn, there is a VPLS after the service provider edge.

DexterPark

Conceptually, A VRF allows you to have separate routing tables in the same sense that VLAN's separate broadcast domains. It would not matter if customer A & B are both connected to the PE Route on the same subnet because they are logically separated. This is a pretty common practice for ISP's.

hitmen

DexterPark wrote: »

Conceptually, A VRF allows you to have separate routing tables in the same sense that VLAN's separate broadcast domains. It would not matter if customer A & B are both connected to the PE Route on the same subnet because they are logically separated. This is a pretty common practice for ISP's.

So you are saying that Cust A and B are in the same VRF and they cannnot ping each other?

Ok. So what should I do IF I want them to ping each other?

her.yang

From what I understand of it: if two customers are on DIFFERENT VRFs, then they cannot communicate with each other. Multiple VRFs can exist on a router, with each VRF able to host different--or even the same--IP spaces. For example, on the same router you could have Customers A and B, both on their own VRF, and both with the same private IP space of 172.16.0.0/16 and this would work. The reason is because since each customer has their own routing table, they will never be able to "see" each other. The only way to have inter-VRF communication is to "leak" routes from one VRF into another VRF. This can be done using several methods. I've actually done an implementation once where I had to leak routes from a VRF into the global routing table using static routes. Another way to do it is to use Multi-Protocol BGP (MP-BGP). I've never had to do that before but from what I read of it, it sounds complicated.

hitmen

Hi,
Can you elaborate how you leak the routes into the global routung table using static route? Thanks

her.yang

Sorry, I had it backwards. I had to leak routes FROM the global routing INTO the VRF. The command structure would look like this though:

ip route vrf BLUE 172.16.0.0 255.255.0.0 10.0.0.1 global

This specifies that in order for the router to reach network 172.16.0.0/16 from the VRF named BLUE, its next hop would be 10.0.0.1, which exists in the global routing table. With this configuration, you've now made the VRF routing table BLUE aware of the existence of the 172.16.0.0/16 network and its global next-hop address 10.0.0.1. Doing a 'show ip route vrf BLUE' should yield the following output:

R2#sh ip route vrf BLUE

Routing Table: BLUE
Codes: C - connected, S - static, R - RIP, M - mobile, 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
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

172.17.0.0/24 is subnetted, 1 subnets
C 172.17.0.0 is directly connected, Loopback0
S 172.16.0.0/16 [1/0] via 10.0.0.1